1 //===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a module pass that applies a variety of small
11 // optimizations for calls to specific well-known function calls (e.g. runtime
12 // library functions). For example, a call to the function "exit(3)" that
13 // occurs within the main() function can be transformed into a simple "return 3"
14 // instruction. Any optimization that takes this form (replace call to library
15 // function with simpler code that provides the same result) belongs in this
18 //===----------------------------------------------------------------------===//
20 #define DEBUG_TYPE "simplify-libcalls"
21 #include "llvm/Constants.h"
22 #include "llvm/DerivedTypes.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/Module.h"
25 #include "llvm/Pass.h"
26 #include "llvm/ADT/hash_map"
27 #include "llvm/ADT/Statistic.h"
28 #include "llvm/Config/config.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Target/TargetData.h"
31 #include "llvm/Transforms/IPO.h"
34 /// This statistic keeps track of the total number of library calls that have
35 /// been simplified regardless of which call it is.
36 STATISTIC(SimplifiedLibCalls, "Number of library calls simplified");
39 // Forward declarations
40 class LibCallOptimization;
41 class SimplifyLibCalls;
43 /// This list is populated by the constructor for LibCallOptimization class.
44 /// Therefore all subclasses are registered here at static initialization time
45 /// and this list is what the SimplifyLibCalls pass uses to apply the individual
46 /// optimizations to the call sites.
47 /// @brief The list of optimizations deriving from LibCallOptimization
48 static LibCallOptimization *OptList = 0;
50 /// This class is the abstract base class for the set of optimizations that
51 /// corresponds to one library call. The SimplifyLibCalls pass will call the
52 /// ValidateCalledFunction method to ask the optimization if a given Function
53 /// is the kind that the optimization can handle. If the subclass returns true,
54 /// then SImplifyLibCalls will also call the OptimizeCall method to perform,
55 /// or attempt to perform, the optimization(s) for the library call. Otherwise,
56 /// OptimizeCall won't be called. Subclasses are responsible for providing the
57 /// name of the library call (strlen, strcpy, etc.) to the LibCallOptimization
58 /// constructor. This is used to efficiently select which call instructions to
59 /// optimize. The criteria for a "lib call" is "anything with well known
60 /// semantics", typically a library function that is defined by an international
61 /// standard. Because the semantics are well known, the optimizations can
62 /// generally short-circuit actually calling the function if there's a simpler
63 /// way (e.g. strlen(X) can be reduced to a constant if X is a constant global).
64 /// @brief Base class for library call optimizations
65 class LibCallOptimization {
66 LibCallOptimization **Prev, *Next;
67 const char *FunctionName; ///< Name of the library call we optimize
69 Statistic occurrences; ///< debug statistic (-debug-only=simplify-libcalls)
72 /// The \p fname argument must be the name of the library function being
73 /// optimized by the subclass.
74 /// @brief Constructor that registers the optimization.
75 LibCallOptimization(const char *FName, const char *Description)
78 , occurrences("simplify-libcalls", Description)
81 // Register this optimizer in the list of optimizations.
85 if (Next) Next->Prev = &Next;
88 /// getNext - All libcall optimizations are chained together into a list,
89 /// return the next one in the list.
90 LibCallOptimization *getNext() { return Next; }
92 /// @brief Deregister from the optlist
93 virtual ~LibCallOptimization() {
95 if (Next) Next->Prev = Prev;
98 /// The implementation of this function in subclasses should determine if
99 /// \p F is suitable for the optimization. This method is called by
100 /// SimplifyLibCalls::runOnModule to short circuit visiting all the call
101 /// sites of such a function if that function is not suitable in the first
102 /// place. If the called function is suitabe, this method should return true;
103 /// false, otherwise. This function should also perform any lazy
104 /// initialization that the LibCallOptimization needs to do, if its to return
105 /// true. This avoids doing initialization until the optimizer is actually
106 /// going to be called upon to do some optimization.
107 /// @brief Determine if the function is suitable for optimization
108 virtual bool ValidateCalledFunction(
109 const Function* F, ///< The function that is the target of call sites
110 SimplifyLibCalls& SLC ///< The pass object invoking us
113 /// The implementations of this function in subclasses is the heart of the
114 /// SimplifyLibCalls algorithm. Sublcasses of this class implement
115 /// OptimizeCall to determine if (a) the conditions are right for optimizing
116 /// the call and (b) to perform the optimization. If an action is taken
117 /// against ci, the subclass is responsible for returning true and ensuring
118 /// that ci is erased from its parent.
119 /// @brief Optimize a call, if possible.
120 virtual bool OptimizeCall(
121 CallInst* ci, ///< The call instruction that should be optimized.
122 SimplifyLibCalls& SLC ///< The pass object invoking us
125 /// @brief Get the name of the library call being optimized
126 const char *getFunctionName() const { return FunctionName; }
128 /// @brief Called by SimplifyLibCalls to update the occurrences statistic.
131 DEBUG(++occurrences);
136 /// This class is an LLVM Pass that applies each of the LibCallOptimization
137 /// instances to all the call sites in a module, relatively efficiently. The
138 /// purpose of this pass is to provide optimizations for calls to well-known
139 /// functions with well-known semantics, such as those in the c library. The
140 /// class provides the basic infrastructure for handling runOnModule. Whenever
141 /// this pass finds a function call, it asks the appropriate optimizer to
142 /// validate the call (ValidateLibraryCall). If it is validated, then
143 /// the OptimizeCall method is also called.
144 /// @brief A ModulePass for optimizing well-known function calls.
145 class SimplifyLibCalls : public ModulePass {
147 /// We need some target data for accurate signature details that are
148 /// target dependent. So we require target data in our AnalysisUsage.
149 /// @brief Require TargetData from AnalysisUsage.
150 virtual void getAnalysisUsage(AnalysisUsage& Info) const {
151 // Ask that the TargetData analysis be performed before us so we can use
153 Info.addRequired<TargetData>();
156 /// For this pass, process all of the function calls in the module, calling
157 /// ValidateLibraryCall and OptimizeCall as appropriate.
158 /// @brief Run all the lib call optimizations on a Module.
159 virtual bool runOnModule(Module &M) {
163 hash_map<std::string, LibCallOptimization*> OptznMap;
164 for (LibCallOptimization *Optzn = OptList; Optzn; Optzn = Optzn->getNext())
165 OptznMap[Optzn->getFunctionName()] = Optzn;
167 // The call optimizations can be recursive. That is, the optimization might
168 // generate a call to another function which can also be optimized. This way
169 // we make the LibCallOptimization instances very specific to the case they
170 // handle. It also means we need to keep running over the function calls in
171 // the module until we don't get any more optimizations possible.
172 bool found_optimization = false;
174 found_optimization = false;
175 for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
176 // All the "well-known" functions are external and have external linkage
177 // because they live in a runtime library somewhere and were (probably)
178 // not compiled by LLVM. So, we only act on external functions that
179 // have external or dllimport linkage and non-empty uses.
180 if (!FI->isExternal() ||
181 !(FI->hasExternalLinkage() || FI->hasDLLImportLinkage()) ||
185 // Get the optimization class that pertains to this function
186 hash_map<std::string, LibCallOptimization*>::iterator OMI =
187 OptznMap.find(FI->getName());
188 if (OMI == OptznMap.end()) continue;
190 LibCallOptimization *CO = OMI->second;
192 // Make sure the called function is suitable for the optimization
193 if (!CO->ValidateCalledFunction(FI, *this))
196 // Loop over each of the uses of the function
197 for (Value::use_iterator UI = FI->use_begin(), UE = FI->use_end();
199 // If the use of the function is a call instruction
200 if (CallInst* CI = dyn_cast<CallInst>(*UI++)) {
201 // Do the optimization on the LibCallOptimization.
202 if (CO->OptimizeCall(CI, *this)) {
203 ++SimplifiedLibCalls;
204 found_optimization = result = true;
210 } while (found_optimization);
215 /// @brief Return the *current* module we're working on.
216 Module* getModule() const { return M; }
218 /// @brief Return the *current* target data for the module we're working on.
219 TargetData* getTargetData() const { return TD; }
221 /// @brief Return the size_t type -- syntactic shortcut
222 const Type* getIntPtrType() const { return TD->getIntPtrType(); }
224 /// @brief Return a Function* for the putchar libcall
225 Function* get_putchar() {
227 putchar_func = M->getOrInsertFunction("putchar", Type::IntTy, Type::IntTy,
232 /// @brief Return a Function* for the puts libcall
233 Function* get_puts() {
235 puts_func = M->getOrInsertFunction("puts", Type::IntTy,
236 PointerType::get(Type::SByteTy),
241 /// @brief Return a Function* for the fputc libcall
242 Function* get_fputc(const Type* FILEptr_type) {
244 fputc_func = M->getOrInsertFunction("fputc", Type::IntTy, Type::IntTy,
249 /// @brief Return a Function* for the fputs libcall
250 Function* get_fputs(const Type* FILEptr_type) {
252 fputs_func = M->getOrInsertFunction("fputs", Type::IntTy,
253 PointerType::get(Type::SByteTy),
258 /// @brief Return a Function* for the fwrite libcall
259 Function* get_fwrite(const Type* FILEptr_type) {
261 fwrite_func = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
262 PointerType::get(Type::SByteTy),
269 /// @brief Return a Function* for the sqrt libcall
270 Function* get_sqrt() {
272 sqrt_func = M->getOrInsertFunction("sqrt", Type::DoubleTy,
273 Type::DoubleTy, NULL);
277 /// @brief Return a Function* for the strlen libcall
278 Function* get_strcpy() {
280 strcpy_func = M->getOrInsertFunction("strcpy",
281 PointerType::get(Type::SByteTy),
282 PointerType::get(Type::SByteTy),
283 PointerType::get(Type::SByteTy),
288 /// @brief Return a Function* for the strlen libcall
289 Function* get_strlen() {
291 strlen_func = M->getOrInsertFunction("strlen", TD->getIntPtrType(),
292 PointerType::get(Type::SByteTy),
297 /// @brief Return a Function* for the memchr libcall
298 Function* get_memchr() {
300 memchr_func = M->getOrInsertFunction("memchr",
301 PointerType::get(Type::SByteTy),
302 PointerType::get(Type::SByteTy),
303 Type::IntTy, TD->getIntPtrType(),
308 /// @brief Return a Function* for the memcpy libcall
309 Function* get_memcpy() {
311 const Type *SBP = PointerType::get(Type::SByteTy);
312 const char *N = TD->getIntPtrType() == Type::UIntTy ?
313 "llvm.memcpy.i32" : "llvm.memcpy.i64";
314 memcpy_func = M->getOrInsertFunction(N, Type::VoidTy, SBP, SBP,
315 TD->getIntPtrType(), Type::UIntTy,
321 Function *getUnaryFloatFunction(const char *Name, Function *&Cache) {
323 Cache = M->getOrInsertFunction(Name, Type::FloatTy, Type::FloatTy, NULL);
327 Function *get_floorf() { return getUnaryFloatFunction("floorf", floorf_func);}
328 Function *get_ceilf() { return getUnaryFloatFunction( "ceilf", ceilf_func);}
329 Function *get_roundf() { return getUnaryFloatFunction("roundf", roundf_func);}
330 Function *get_rintf() { return getUnaryFloatFunction( "rintf", rintf_func);}
331 Function *get_nearbyintf() { return getUnaryFloatFunction("nearbyintf",
334 /// @brief Reset our cached data for a new Module
335 void reset(Module& mod) {
337 TD = &getAnalysis<TargetData>();
356 /// Caches for function pointers.
357 Function *putchar_func, *puts_func;
358 Function *fputc_func, *fputs_func, *fwrite_func;
359 Function *memcpy_func, *memchr_func;
361 Function *strcpy_func, *strlen_func;
362 Function *floorf_func, *ceilf_func, *roundf_func;
363 Function *rintf_func, *nearbyintf_func;
364 Module *M; ///< Cached Module
365 TargetData *TD; ///< Cached TargetData
369 RegisterPass<SimplifyLibCalls>
370 X("simplify-libcalls", "Simplify well-known library calls");
372 } // anonymous namespace
374 // The only public symbol in this file which just instantiates the pass object
375 ModulePass *llvm::createSimplifyLibCallsPass() {
376 return new SimplifyLibCalls();
379 // Classes below here, in the anonymous namespace, are all subclasses of the
380 // LibCallOptimization class, each implementing all optimizations possible for a
381 // single well-known library call. Each has a static singleton instance that
382 // auto registers it into the "optlist" global above.
385 // Forward declare utility functions.
386 bool getConstantStringLength(Value* V, uint64_t& len, ConstantArray** A = 0 );
387 Value *CastToCStr(Value *V, Instruction &IP);
389 /// This LibCallOptimization will find instances of a call to "exit" that occurs
390 /// within the "main" function and change it to a simple "ret" instruction with
391 /// the same value passed to the exit function. When this is done, it splits the
392 /// basic block at the exit(3) call and deletes the call instruction.
393 /// @brief Replace calls to exit in main with a simple return
394 struct ExitInMainOptimization : public LibCallOptimization {
395 ExitInMainOptimization() : LibCallOptimization("exit",
396 "Number of 'exit' calls simplified") {}
398 // Make sure the called function looks like exit (int argument, int return
399 // type, external linkage, not varargs).
400 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
401 return F->arg_size() >= 1 && F->arg_begin()->getType()->isInteger();
404 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
405 // To be careful, we check that the call to exit is coming from "main", that
406 // main has external linkage, and the return type of main and the argument
407 // to exit have the same type.
408 Function *from = ci->getParent()->getParent();
409 if (from->hasExternalLinkage())
410 if (from->getReturnType() == ci->getOperand(1)->getType())
411 if (from->getName() == "main") {
412 // Okay, time to actually do the optimization. First, get the basic
413 // block of the call instruction
414 BasicBlock* bb = ci->getParent();
416 // Create a return instruction that we'll replace the call with.
417 // Note that the argument of the return is the argument of the call
419 new ReturnInst(ci->getOperand(1), ci);
421 // Split the block at the call instruction which places it in a new
423 bb->splitBasicBlock(ci);
425 // The block split caused a branch instruction to be inserted into
426 // the end of the original block, right after the return instruction
427 // that we put there. That's not a valid block, so delete the branch
429 bb->getInstList().pop_back();
431 // Now we can finally get rid of the call instruction which now lives
432 // in the new basic block.
433 ci->eraseFromParent();
435 // Optimization succeeded, return true.
438 // We didn't pass the criteria for this optimization so return false
441 } ExitInMainOptimizer;
443 /// This LibCallOptimization will simplify a call to the strcat library
444 /// function. The simplification is possible only if the string being
445 /// concatenated is a constant array or a constant expression that results in
446 /// a constant string. In this case we can replace it with strlen + llvm.memcpy
447 /// of the constant string. Both of these calls are further reduced, if possible
448 /// on subsequent passes.
449 /// @brief Simplify the strcat library function.
450 struct StrCatOptimization : public LibCallOptimization {
452 /// @brief Default constructor
453 StrCatOptimization() : LibCallOptimization("strcat",
454 "Number of 'strcat' calls simplified") {}
458 /// @brief Make sure that the "strcat" function has the right prototype
459 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
460 if (f->getReturnType() == PointerType::get(Type::SByteTy))
461 if (f->arg_size() == 2)
463 Function::const_arg_iterator AI = f->arg_begin();
464 if (AI++->getType() == PointerType::get(Type::SByteTy))
465 if (AI->getType() == PointerType::get(Type::SByteTy))
467 // Indicate this is a suitable call type.
474 /// @brief Optimize the strcat library function
475 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
476 // Extract some information from the instruction
477 Value* dest = ci->getOperand(1);
478 Value* src = ci->getOperand(2);
480 // Extract the initializer (while making numerous checks) from the
481 // source operand of the call to strcat. If we get null back, one of
482 // a variety of checks in get_GVInitializer failed
484 if (!getConstantStringLength(src,len))
487 // Handle the simple, do-nothing case
489 ci->replaceAllUsesWith(dest);
490 ci->eraseFromParent();
494 // Increment the length because we actually want to memcpy the null
495 // terminator as well.
498 // We need to find the end of the destination string. That's where the
499 // memory is to be moved to. We just generate a call to strlen (further
500 // optimized in another pass). Note that the SLC.get_strlen() call
501 // caches the Function* for us.
502 CallInst* strlen_inst =
503 new CallInst(SLC.get_strlen(), dest, dest->getName()+".len",ci);
505 // Now that we have the destination's length, we must index into the
506 // destination's pointer to get the actual memcpy destination (end of
507 // the string .. we're concatenating).
508 std::vector<Value*> idx;
509 idx.push_back(strlen_inst);
510 GetElementPtrInst* gep =
511 new GetElementPtrInst(dest,idx,dest->getName()+".indexed",ci);
513 // We have enough information to now generate the memcpy call to
514 // do the concatenation for us.
515 std::vector<Value*> vals;
516 vals.push_back(gep); // destination
517 vals.push_back(ci->getOperand(2)); // source
518 vals.push_back(ConstantInt::get(SLC.getIntPtrType(),len)); // length
519 vals.push_back(ConstantInt::get(Type::UIntTy,1)); // alignment
520 new CallInst(SLC.get_memcpy(), vals, "", ci);
522 // Finally, substitute the first operand of the strcat call for the
523 // strcat call itself since strcat returns its first operand; and,
524 // kill the strcat CallInst.
525 ci->replaceAllUsesWith(dest);
526 ci->eraseFromParent();
531 /// This LibCallOptimization will simplify a call to the strchr library
532 /// function. It optimizes out cases where the arguments are both constant
533 /// and the result can be determined statically.
534 /// @brief Simplify the strcmp library function.
535 struct StrChrOptimization : public LibCallOptimization {
537 StrChrOptimization() : LibCallOptimization("strchr",
538 "Number of 'strchr' calls simplified") {}
540 /// @brief Make sure that the "strchr" function has the right prototype
541 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
542 if (f->getReturnType() == PointerType::get(Type::SByteTy) &&
548 /// @brief Perform the strchr optimizations
549 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
550 // If there aren't three operands, bail
551 if (ci->getNumOperands() != 3)
554 // Check that the first argument to strchr is a constant array of sbyte.
555 // If it is, get the length and data, otherwise return false.
557 ConstantArray* CA = 0;
558 if (!getConstantStringLength(ci->getOperand(1),len,&CA))
561 // Check that the second argument to strchr is a constant int. If it isn't
562 // a constant signed integer, we can try an alternate optimization
563 ConstantInt* CSI = dyn_cast<ConstantInt>(ci->getOperand(2));
564 if (!CSI || CSI->getType()->isUnsigned() ) {
565 // The second operand is not constant, or not signed. Just lower this to
566 // memchr since we know the length of the string since it is constant.
567 Function* f = SLC.get_memchr();
568 std::vector<Value*> args;
569 args.push_back(ci->getOperand(1));
570 args.push_back(ci->getOperand(2));
571 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
572 ci->replaceAllUsesWith( new CallInst(f,args,ci->getName(),ci));
573 ci->eraseFromParent();
577 // Get the character we're looking for
578 int64_t chr = CSI->getSExtValue();
580 // Compute the offset
582 bool char_found = false;
583 for (uint64_t i = 0; i < len; ++i) {
584 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
585 // Check for the null terminator
586 if (CI->isNullValue())
587 break; // we found end of string
588 else if (CI->getSExtValue() == chr) {
596 // strchr(s,c) -> offset_of_in(c,s)
597 // (if c is a constant integer and s is a constant string)
599 std::vector<Value*> indices;
600 indices.push_back(ConstantInt::get(Type::ULongTy,offset));
601 GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1),indices,
602 ci->getOperand(1)->getName()+".strchr",ci);
603 ci->replaceAllUsesWith(GEP);
605 ci->replaceAllUsesWith(
606 ConstantPointerNull::get(PointerType::get(Type::SByteTy)));
608 ci->eraseFromParent();
613 /// This LibCallOptimization will simplify a call to the strcmp library
614 /// function. It optimizes out cases where one or both arguments are constant
615 /// and the result can be determined statically.
616 /// @brief Simplify the strcmp library function.
617 struct StrCmpOptimization : public LibCallOptimization {
619 StrCmpOptimization() : LibCallOptimization("strcmp",
620 "Number of 'strcmp' calls simplified") {}
622 /// @brief Make sure that the "strcmp" function has the right prototype
623 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
624 return F->getReturnType() == Type::IntTy && F->arg_size() == 2;
627 /// @brief Perform the strcmp optimization
628 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
629 // First, check to see if src and destination are the same. If they are,
630 // then the optimization is to replace the CallInst with a constant 0
631 // because the call is a no-op.
632 Value* s1 = ci->getOperand(1);
633 Value* s2 = ci->getOperand(2);
636 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
637 ci->eraseFromParent();
641 bool isstr_1 = false;
644 if (getConstantStringLength(s1,len_1,&A1)) {
647 // strcmp("",x) -> *x
649 new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
651 CastInst::create(Instruction::SExt, load, Type::IntTy,
652 ci->getName()+".int", ci);
653 ci->replaceAllUsesWith(cast);
654 ci->eraseFromParent();
659 bool isstr_2 = false;
662 if (getConstantStringLength(s2, len_2, &A2)) {
665 // strcmp(x,"") -> *x
667 new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
669 CastInst::create(Instruction::SExt, load, Type::IntTy,
670 ci->getName()+".int", ci);
671 ci->replaceAllUsesWith(cast);
672 ci->eraseFromParent();
677 if (isstr_1 && isstr_2) {
678 // strcmp(x,y) -> cnst (if both x and y are constant strings)
679 std::string str1 = A1->getAsString();
680 std::string str2 = A2->getAsString();
681 int result = strcmp(str1.c_str(), str2.c_str());
682 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,result));
683 ci->eraseFromParent();
690 /// This LibCallOptimization will simplify a call to the strncmp library
691 /// function. It optimizes out cases where one or both arguments are constant
692 /// and the result can be determined statically.
693 /// @brief Simplify the strncmp library function.
694 struct StrNCmpOptimization : public LibCallOptimization {
696 StrNCmpOptimization() : LibCallOptimization("strncmp",
697 "Number of 'strncmp' calls simplified") {}
699 /// @brief Make sure that the "strncmp" function has the right prototype
700 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
701 if (f->getReturnType() == Type::IntTy && f->arg_size() == 3)
706 /// @brief Perform the strncpy optimization
707 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
708 // First, check to see if src and destination are the same. If they are,
709 // then the optimization is to replace the CallInst with a constant 0
710 // because the call is a no-op.
711 Value* s1 = ci->getOperand(1);
712 Value* s2 = ci->getOperand(2);
714 // strncmp(x,x,l) -> 0
715 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
716 ci->eraseFromParent();
720 // Check the length argument, if it is Constant zero then the strings are
722 uint64_t len_arg = 0;
723 bool len_arg_is_const = false;
724 if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
725 len_arg_is_const = true;
726 len_arg = len_CI->getZExtValue();
728 // strncmp(x,y,0) -> 0
729 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
730 ci->eraseFromParent();
735 bool isstr_1 = false;
738 if (getConstantStringLength(s1, len_1, &A1)) {
741 // strncmp("",x) -> *x
742 LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
744 CastInst::create(Instruction::SExt, load, Type::IntTy,
745 ci->getName()+".int", ci);
746 ci->replaceAllUsesWith(cast);
747 ci->eraseFromParent();
752 bool isstr_2 = false;
755 if (getConstantStringLength(s2,len_2,&A2)) {
758 // strncmp(x,"") -> *x
759 LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
761 CastInst::create(Instruction::SExt, load, Type::IntTy,
762 ci->getName()+".int", ci);
763 ci->replaceAllUsesWith(cast);
764 ci->eraseFromParent();
769 if (isstr_1 && isstr_2 && len_arg_is_const) {
770 // strncmp(x,y,const) -> constant
771 std::string str1 = A1->getAsString();
772 std::string str2 = A2->getAsString();
773 int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
774 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,result));
775 ci->eraseFromParent();
782 /// This LibCallOptimization will simplify a call to the strcpy library
783 /// function. Two optimizations are possible:
784 /// (1) If src and dest are the same and not volatile, just return dest
785 /// (2) If the src is a constant then we can convert to llvm.memmove
786 /// @brief Simplify the strcpy library function.
787 struct StrCpyOptimization : public LibCallOptimization {
789 StrCpyOptimization() : LibCallOptimization("strcpy",
790 "Number of 'strcpy' calls simplified") {}
792 /// @brief Make sure that the "strcpy" function has the right prototype
793 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
794 if (f->getReturnType() == PointerType::get(Type::SByteTy))
795 if (f->arg_size() == 2) {
796 Function::const_arg_iterator AI = f->arg_begin();
797 if (AI++->getType() == PointerType::get(Type::SByteTy))
798 if (AI->getType() == PointerType::get(Type::SByteTy)) {
799 // Indicate this is a suitable call type.
806 /// @brief Perform the strcpy optimization
807 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
808 // First, check to see if src and destination are the same. If they are,
809 // then the optimization is to replace the CallInst with the destination
810 // because the call is a no-op. Note that this corresponds to the
811 // degenerate strcpy(X,X) case which should have "undefined" results
812 // according to the C specification. However, it occurs sometimes and
813 // we optimize it as a no-op.
814 Value* dest = ci->getOperand(1);
815 Value* src = ci->getOperand(2);
817 ci->replaceAllUsesWith(dest);
818 ci->eraseFromParent();
822 // Get the length of the constant string referenced by the second operand,
823 // the "src" parameter. Fail the optimization if we can't get the length
824 // (note that getConstantStringLength does lots of checks to make sure this
827 if (!getConstantStringLength(ci->getOperand(2),len))
830 // If the constant string's length is zero we can optimize this by just
831 // doing a store of 0 at the first byte of the destination
833 new StoreInst(ConstantInt::get(Type::SByteTy,0),ci->getOperand(1),ci);
834 ci->replaceAllUsesWith(dest);
835 ci->eraseFromParent();
839 // Increment the length because we actually want to memcpy the null
840 // terminator as well.
843 // We have enough information to now generate the memcpy call to
844 // do the concatenation for us.
845 std::vector<Value*> vals;
846 vals.push_back(dest); // destination
847 vals.push_back(src); // source
848 vals.push_back(ConstantInt::get(SLC.getIntPtrType(),len)); // length
849 vals.push_back(ConstantInt::get(Type::UIntTy,1)); // alignment
850 new CallInst(SLC.get_memcpy(), vals, "", ci);
852 // Finally, substitute the first operand of the strcat call for the
853 // strcat call itself since strcat returns its first operand; and,
854 // kill the strcat CallInst.
855 ci->replaceAllUsesWith(dest);
856 ci->eraseFromParent();
861 /// This LibCallOptimization will simplify a call to the strlen library
862 /// function by replacing it with a constant value if the string provided to
863 /// it is a constant array.
864 /// @brief Simplify the strlen library function.
865 struct StrLenOptimization : public LibCallOptimization {
866 StrLenOptimization() : LibCallOptimization("strlen",
867 "Number of 'strlen' calls simplified") {}
869 /// @brief Make sure that the "strlen" function has the right prototype
870 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
872 if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
873 if (f->arg_size() == 1)
874 if (Function::const_arg_iterator AI = f->arg_begin())
875 if (AI->getType() == PointerType::get(Type::SByteTy))
880 /// @brief Perform the strlen optimization
881 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
883 // Make sure we're dealing with an sbyte* here.
884 Value* str = ci->getOperand(1);
885 if (str->getType() != PointerType::get(Type::SByteTy))
888 // Does the call to strlen have exactly one use?
890 // Is that single use a binary operator?
891 if (BinaryOperator* bop = dyn_cast<BinaryOperator>(ci->use_back()))
892 // Is it compared against a constant integer?
893 if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
895 // Get the value the strlen result is compared to
896 uint64_t val = CI->getZExtValue();
898 // If its compared against length 0 with == or !=
900 (bop->getOpcode() == Instruction::SetEQ ||
901 bop->getOpcode() == Instruction::SetNE))
903 // strlen(x) != 0 -> *x != 0
904 // strlen(x) == 0 -> *x == 0
905 LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
906 BinaryOperator* rbop = BinaryOperator::create(bop->getOpcode(),
907 load, ConstantInt::get(Type::SByteTy,0),
908 bop->getName()+".strlen", ci);
909 bop->replaceAllUsesWith(rbop);
910 bop->eraseFromParent();
911 ci->eraseFromParent();
916 // Get the length of the constant string operand
918 if (!getConstantStringLength(ci->getOperand(1),len))
921 // strlen("xyz") -> 3 (for example)
922 const Type *Ty = SLC.getTargetData()->getIntPtrType();
924 ci->replaceAllUsesWith(ConstantInt::get(Ty, len));
926 ci->replaceAllUsesWith(ConstantInt::get(Ty, len));
928 ci->eraseFromParent();
933 /// IsOnlyUsedInEqualsComparison - Return true if it only matters that the value
934 /// is equal or not-equal to zero.
935 static bool IsOnlyUsedInEqualsZeroComparison(Instruction *I) {
936 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
938 Instruction *User = cast<Instruction>(*UI);
939 if (User->getOpcode() == Instruction::SetNE ||
940 User->getOpcode() == Instruction::SetEQ) {
941 if (isa<Constant>(User->getOperand(1)) &&
942 cast<Constant>(User->getOperand(1))->isNullValue())
944 } else if (CastInst *CI = dyn_cast<CastInst>(User))
945 if (CI->getType() == Type::BoolTy)
947 // Unknown instruction.
953 /// This memcmpOptimization will simplify a call to the memcmp library
955 struct memcmpOptimization : public LibCallOptimization {
956 /// @brief Default Constructor
958 : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
960 /// @brief Make sure that the "memcmp" function has the right prototype
961 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
962 Function::const_arg_iterator AI = F->arg_begin();
963 if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
964 if (!isa<PointerType>((++AI)->getType())) return false;
965 if (!(++AI)->getType()->isInteger()) return false;
966 if (!F->getReturnType()->isInteger()) return false;
970 /// Because of alignment and instruction information that we don't have, we
971 /// leave the bulk of this to the code generators.
973 /// Note that we could do much more if we could force alignment on otherwise
974 /// small aligned allocas, or if we could indicate that loads have a small
976 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
977 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
979 // If the two operands are the same, return zero.
981 // memcmp(s,s,x) -> 0
982 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
983 CI->eraseFromParent();
987 // Make sure we have a constant length.
988 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
989 if (!LenC) return false;
990 uint64_t Len = LenC->getZExtValue();
992 // If the length is zero, this returns 0.
995 // memcmp(s1,s2,0) -> 0
996 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
997 CI->eraseFromParent();
1000 // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
1001 const Type *UCharPtr = PointerType::get(Type::UByteTy);
1002 CastInst *Op1Cast = CastInst::create(
1003 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1004 CastInst *Op2Cast = CastInst::create(
1005 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1006 Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
1007 Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
1008 Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
1009 if (RV->getType() != CI->getType())
1010 RV = CastInst::createIntegerCast(RV, CI->getType(), false,
1012 CI->replaceAllUsesWith(RV);
1013 CI->eraseFromParent();
1017 if (IsOnlyUsedInEqualsZeroComparison(CI)) {
1018 // TODO: IF both are aligned, use a short load/compare.
1020 // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
1021 const Type *UCharPtr = PointerType::get(Type::UByteTy);
1022 CastInst *Op1Cast = CastInst::create(
1023 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1024 CastInst *Op2Cast = CastInst::create(
1025 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1026 Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
1027 Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
1028 Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
1029 CI->getName()+".d1", CI);
1030 Constant *One = ConstantInt::get(Type::IntTy, 1);
1031 Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
1032 Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
1033 Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
1034 Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
1035 Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
1036 CI->getName()+".d1", CI);
1037 Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
1038 if (Or->getType() != CI->getType())
1039 Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/,
1041 CI->replaceAllUsesWith(Or);
1042 CI->eraseFromParent();
1055 /// This LibCallOptimization will simplify a call to the memcpy library
1056 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1057 /// bytes depending on the length of the string and the alignment. Additional
1058 /// optimizations are possible in code generation (sequence of immediate store)
1059 /// @brief Simplify the memcpy library function.
1060 struct LLVMMemCpyMoveOptzn : public LibCallOptimization {
1061 LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
1062 : LibCallOptimization(fname, desc) {}
1064 /// @brief Make sure that the "memcpy" function has the right prototype
1065 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
1066 // Just make sure this has 4 arguments per LLVM spec.
1067 return (f->arg_size() == 4);
1070 /// Because of alignment and instruction information that we don't have, we
1071 /// leave the bulk of this to the code generators. The optimization here just
1072 /// deals with a few degenerate cases where the length of the string and the
1073 /// alignment match the sizes of our intrinsic types so we can do a load and
1074 /// store instead of the memcpy call.
1075 /// @brief Perform the memcpy optimization.
1076 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
1077 // Make sure we have constant int values to work with
1078 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1081 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1085 // If the length is larger than the alignment, we can't optimize
1086 uint64_t len = LEN->getZExtValue();
1087 uint64_t alignment = ALIGN->getZExtValue();
1089 alignment = 1; // Alignment 0 is identity for alignment 1
1090 if (len > alignment)
1093 // Get the type we will cast to, based on size of the string
1094 Value* dest = ci->getOperand(1);
1095 Value* src = ci->getOperand(2);
1100 // memcpy(d,s,0,a) -> noop
1101 ci->eraseFromParent();
1103 case 1: castType = Type::SByteTy; break;
1104 case 2: castType = Type::ShortTy; break;
1105 case 4: castType = Type::IntTy; break;
1106 case 8: castType = Type::LongTy; break;
1111 // Cast source and dest to the right sized primitive and then load/store
1112 CastInst* SrcCast = CastInst::create(Instruction::BitCast,
1113 src, PointerType::get(castType), src->getName()+".cast", ci);
1114 CastInst* DestCast = CastInst::create(Instruction::BitCast,
1115 dest, PointerType::get(castType),dest->getName()+".cast", ci);
1116 LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
1117 new StoreInst(LI, DestCast, ci);
1118 ci->eraseFromParent();
1123 /// This LibCallOptimization will simplify a call to the memcpy/memmove library
1125 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
1126 "Number of 'llvm.memcpy' calls simplified");
1127 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
1128 "Number of 'llvm.memcpy' calls simplified");
1129 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
1130 "Number of 'llvm.memmove' calls simplified");
1131 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
1132 "Number of 'llvm.memmove' calls simplified");
1134 /// This LibCallOptimization will simplify a call to the memset library
1135 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1136 /// bytes depending on the length argument.
1137 struct LLVMMemSetOptimization : public LibCallOptimization {
1138 /// @brief Default Constructor
1139 LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
1140 "Number of 'llvm.memset' calls simplified") {}
1142 /// @brief Make sure that the "memset" function has the right prototype
1143 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
1144 // Just make sure this has 3 arguments per LLVM spec.
1145 return F->arg_size() == 4;
1148 /// Because of alignment and instruction information that we don't have, we
1149 /// leave the bulk of this to the code generators. The optimization here just
1150 /// deals with a few degenerate cases where the length parameter is constant
1151 /// and the alignment matches the sizes of our intrinsic types so we can do
1152 /// store instead of the memcpy call. Other calls are transformed into the
1153 /// llvm.memset intrinsic.
1154 /// @brief Perform the memset optimization.
1155 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
1156 // Make sure we have constant int values to work with
1157 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1160 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1164 // Extract the length and alignment
1165 uint64_t len = LEN->getZExtValue();
1166 uint64_t alignment = ALIGN->getZExtValue();
1168 // Alignment 0 is identity for alignment 1
1172 // If the length is zero, this is a no-op
1174 // memset(d,c,0,a) -> noop
1175 ci->eraseFromParent();
1179 // If the length is larger than the alignment, we can't optimize
1180 if (len > alignment)
1183 // Make sure we have a constant ubyte to work with so we can extract
1184 // the value to be filled.
1185 ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
1188 if (FILL->getType() != Type::UByteTy)
1191 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
1193 // Extract the fill character
1194 uint64_t fill_char = FILL->getZExtValue();
1195 uint64_t fill_value = fill_char;
1197 // Get the type we will cast to, based on size of memory area to fill, and
1198 // and the value we will store there.
1199 Value* dest = ci->getOperand(1);
1203 castType = Type::UByteTy;
1206 castType = Type::UShortTy;
1207 fill_value |= fill_char << 8;
1210 castType = Type::UIntTy;
1211 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1214 castType = Type::ULongTy;
1215 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1216 fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
1217 fill_value |= fill_char << 56;
1223 // Cast dest to the right sized primitive and then load/store
1224 CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType),
1225 dest->getName()+".cast", ci);
1226 new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
1227 ci->eraseFromParent();
1232 LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
1233 LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
1236 /// This LibCallOptimization will simplify calls to the "pow" library
1237 /// function. It looks for cases where the result of pow is well known and
1238 /// substitutes the appropriate value.
1239 /// @brief Simplify the pow library function.
1240 struct PowOptimization : public LibCallOptimization {
1242 /// @brief Default Constructor
1243 PowOptimization() : LibCallOptimization("pow",
1244 "Number of 'pow' calls simplified") {}
1246 /// @brief Make sure that the "pow" function has the right prototype
1247 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1248 // Just make sure this has 2 arguments
1249 return (f->arg_size() == 2);
1252 /// @brief Perform the pow optimization.
1253 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1254 const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
1255 Value* base = ci->getOperand(1);
1256 Value* expn = ci->getOperand(2);
1257 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
1258 double Op1V = Op1->getValue();
1260 // pow(1.0,x) -> 1.0
1261 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1262 ci->eraseFromParent();
1265 } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
1266 double Op2V = Op2->getValue();
1268 // pow(x,0.0) -> 1.0
1269 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1270 ci->eraseFromParent();
1272 } else if (Op2V == 0.5) {
1273 // pow(x,0.5) -> sqrt(x)
1274 CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
1275 ci->getName()+".pow",ci);
1276 ci->replaceAllUsesWith(sqrt_inst);
1277 ci->eraseFromParent();
1279 } else if (Op2V == 1.0) {
1281 ci->replaceAllUsesWith(base);
1282 ci->eraseFromParent();
1284 } else if (Op2V == -1.0) {
1285 // pow(x,-1.0) -> 1.0/x
1286 BinaryOperator* div_inst= BinaryOperator::createFDiv(
1287 ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
1288 ci->replaceAllUsesWith(div_inst);
1289 ci->eraseFromParent();
1293 return false; // opt failed
1297 /// This LibCallOptimization will simplify calls to the "printf" library
1298 /// function. It looks for cases where the result of printf is not used and the
1299 /// operation can be reduced to something simpler.
1300 /// @brief Simplify the printf library function.
1301 struct PrintfOptimization : public LibCallOptimization {
1303 /// @brief Default Constructor
1304 PrintfOptimization() : LibCallOptimization("printf",
1305 "Number of 'printf' calls simplified") {}
1307 /// @brief Make sure that the "printf" function has the right prototype
1308 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1309 // Just make sure this has at least 1 arguments
1310 return (f->arg_size() >= 1);
1313 /// @brief Perform the printf optimization.
1314 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1315 // If the call has more than 2 operands, we can't optimize it
1316 if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
1319 // If the result of the printf call is used, none of these optimizations
1321 if (!ci->use_empty())
1324 // All the optimizations depend on the length of the first argument and the
1325 // fact that it is a constant string array. Check that now
1327 ConstantArray* CA = 0;
1328 if (!getConstantStringLength(ci->getOperand(1), len, &CA))
1331 if (len != 2 && len != 3)
1334 // The first character has to be a %
1335 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1336 if (CI->getZExtValue() != '%')
1339 // Get the second character and switch on its value
1340 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1341 switch (CI->getZExtValue()) {
1345 dyn_cast<ConstantInt>(CA->getOperand(2))->getZExtValue() != '\n')
1348 // printf("%s\n",str) -> puts(str)
1349 Function* puts_func = SLC.get_puts();
1352 std::vector<Value*> args;
1353 args.push_back(CastToCStr(ci->getOperand(2), *ci));
1354 new CallInst(puts_func,args,ci->getName(),ci);
1355 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,len));
1360 // printf("%c",c) -> putchar(c)
1364 Function* putchar_func = SLC.get_putchar();
1367 CastInst* cast = CastInst::createSExtOrBitCast(
1368 ci->getOperand(2), Type::IntTy, CI->getName()+".int", ci);
1369 new CallInst(putchar_func, cast, "", ci);
1370 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy, 1));
1376 ci->eraseFromParent();
1381 /// This LibCallOptimization will simplify calls to the "fprintf" library
1382 /// function. It looks for cases where the result of fprintf is not used and the
1383 /// operation can be reduced to something simpler.
1384 /// @brief Simplify the fprintf library function.
1385 struct FPrintFOptimization : public LibCallOptimization {
1387 /// @brief Default Constructor
1388 FPrintFOptimization() : LibCallOptimization("fprintf",
1389 "Number of 'fprintf' calls simplified") {}
1391 /// @brief Make sure that the "fprintf" function has the right prototype
1392 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1393 // Just make sure this has at least 2 arguments
1394 return (f->arg_size() >= 2);
1397 /// @brief Perform the fprintf optimization.
1398 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1399 // If the call has more than 3 operands, we can't optimize it
1400 if (ci->getNumOperands() > 4 || ci->getNumOperands() <= 2)
1403 // If the result of the fprintf call is used, none of these optimizations
1405 if (!ci->use_empty())
1408 // All the optimizations depend on the length of the second argument and the
1409 // fact that it is a constant string array. Check that now
1411 ConstantArray* CA = 0;
1412 if (!getConstantStringLength(ci->getOperand(2), len, &CA))
1415 if (ci->getNumOperands() == 3) {
1416 // Make sure there's no % in the constant array
1417 for (unsigned i = 0; i < len; ++i) {
1418 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1419 // Check for the null terminator
1420 if (CI->getZExtValue() == '%')
1421 return false; // we found end of string
1427 // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
1428 const Type* FILEptr_type = ci->getOperand(1)->getType();
1429 Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
1433 // Make sure that the fprintf() and fwrite() functions both take the
1434 // same type of char pointer.
1435 if (ci->getOperand(2)->getType() !=
1436 fwrite_func->getFunctionType()->getParamType(0))
1439 std::vector<Value*> args;
1440 args.push_back(ci->getOperand(2));
1441 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1442 args.push_back(ConstantInt::get(SLC.getIntPtrType(),1));
1443 args.push_back(ci->getOperand(1));
1444 new CallInst(fwrite_func,args,ci->getName(),ci);
1445 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,len));
1446 ci->eraseFromParent();
1450 // The remaining optimizations require the format string to be length 2
1455 // The first character has to be a %
1456 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1457 if (CI->getZExtValue() != '%')
1460 // Get the second character and switch on its value
1461 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1462 switch (CI->getZExtValue()) {
1466 ConstantArray* CA = 0;
1467 if (getConstantStringLength(ci->getOperand(3), len, &CA)) {
1468 // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
1469 const Type* FILEptr_type = ci->getOperand(1)->getType();
1470 Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
1473 std::vector<Value*> args;
1474 args.push_back(CastToCStr(ci->getOperand(3), *ci));
1475 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1476 args.push_back(ConstantInt::get(SLC.getIntPtrType(),1));
1477 args.push_back(ci->getOperand(1));
1478 new CallInst(fwrite_func,args,ci->getName(),ci);
1479 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,len));
1481 // fprintf(file,"%s",str) -> fputs(str,file)
1482 const Type* FILEptr_type = ci->getOperand(1)->getType();
1483 Function* fputs_func = SLC.get_fputs(FILEptr_type);
1486 std::vector<Value*> args;
1487 args.push_back(CastToCStr(ci->getOperand(3), *ci));
1488 args.push_back(ci->getOperand(1));
1489 new CallInst(fputs_func,args,ci->getName(),ci);
1490 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,len));
1496 // fprintf(file,"%c",c) -> fputc(c,file)
1497 const Type* FILEptr_type = ci->getOperand(1)->getType();
1498 Function* fputc_func = SLC.get_fputc(FILEptr_type);
1501 CastInst* cast = CastInst::createSExtOrBitCast(
1502 ci->getOperand(3), Type::IntTy, CI->getName()+".int", ci);
1503 new CallInst(fputc_func,cast,ci->getOperand(1),"",ci);
1504 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,1));
1510 ci->eraseFromParent();
1515 /// This LibCallOptimization will simplify calls to the "sprintf" library
1516 /// function. It looks for cases where the result of sprintf is not used and the
1517 /// operation can be reduced to something simpler.
1518 /// @brief Simplify the sprintf library function.
1519 struct SPrintFOptimization : public LibCallOptimization {
1521 /// @brief Default Constructor
1522 SPrintFOptimization() : LibCallOptimization("sprintf",
1523 "Number of 'sprintf' calls simplified") {}
1525 /// @brief Make sure that the "fprintf" function has the right prototype
1526 virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
1527 // Just make sure this has at least 2 arguments
1528 return (f->getReturnType() == Type::IntTy && f->arg_size() >= 2);
1531 /// @brief Perform the sprintf optimization.
1532 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1533 // If the call has more than 3 operands, we can't optimize it
1534 if (ci->getNumOperands() > 4 || ci->getNumOperands() < 3)
1537 // All the optimizations depend on the length of the second argument and the
1538 // fact that it is a constant string array. Check that now
1540 ConstantArray* CA = 0;
1541 if (!getConstantStringLength(ci->getOperand(2), len, &CA))
1544 if (ci->getNumOperands() == 3) {
1546 // If the length is 0, we just need to store a null byte
1547 new StoreInst(ConstantInt::get(Type::SByteTy,0),ci->getOperand(1),ci);
1548 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
1549 ci->eraseFromParent();
1553 // Make sure there's no % in the constant array
1554 for (unsigned i = 0; i < len; ++i) {
1555 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1556 // Check for the null terminator
1557 if (CI->getZExtValue() == '%')
1558 return false; // we found a %, can't optimize
1560 return false; // initializer is not constant int, can't optimize
1564 // Increment length because we want to copy the null byte too
1567 // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
1568 Function* memcpy_func = SLC.get_memcpy();
1571 std::vector<Value*> args;
1572 args.push_back(ci->getOperand(1));
1573 args.push_back(ci->getOperand(2));
1574 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1575 args.push_back(ConstantInt::get(Type::UIntTy,1));
1576 new CallInst(memcpy_func,args,"",ci);
1577 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,len));
1578 ci->eraseFromParent();
1582 // The remaining optimizations require the format string to be length 2
1587 // The first character has to be a %
1588 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1589 if (CI->getZExtValue() != '%')
1592 // Get the second character and switch on its value
1593 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1594 switch (CI->getZExtValue()) {
1596 // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1597 Function* strlen_func = SLC.get_strlen();
1598 Function* memcpy_func = SLC.get_memcpy();
1599 if (!strlen_func || !memcpy_func)
1602 Value *Len = new CallInst(strlen_func, CastToCStr(ci->getOperand(3), *ci),
1603 ci->getOperand(3)->getName()+".len", ci);
1604 Value *Len1 = BinaryOperator::createAdd(Len,
1605 ConstantInt::get(Len->getType(), 1),
1606 Len->getName()+"1", ci);
1607 if (Len1->getType() != SLC.getIntPtrType())
1608 Len1 = CastInst::createIntegerCast(Len1, SLC.getIntPtrType(), false,
1609 Len1->getName(), ci);
1610 std::vector<Value*> args;
1611 args.push_back(CastToCStr(ci->getOperand(1), *ci));
1612 args.push_back(CastToCStr(ci->getOperand(3), *ci));
1613 args.push_back(Len1);
1614 args.push_back(ConstantInt::get(Type::UIntTy,1));
1615 new CallInst(memcpy_func, args, "", ci);
1617 // The strlen result is the unincremented number of bytes in the string.
1618 if (!ci->use_empty()) {
1619 if (Len->getType() != ci->getType())
1620 Len = CastInst::createIntegerCast(Len, ci->getType(), false,
1621 Len->getName(), ci);
1622 ci->replaceAllUsesWith(Len);
1624 ci->eraseFromParent();
1628 // sprintf(dest,"%c",chr) -> store chr, dest
1629 CastInst* cast = CastInst::createTruncOrBitCast(
1630 ci->getOperand(3), Type::SByteTy, "char", ci);
1631 new StoreInst(cast, ci->getOperand(1), ci);
1632 GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
1633 ConstantInt::get(Type::UIntTy,1),ci->getOperand(1)->getName()+".end",
1635 new StoreInst(ConstantInt::get(Type::SByteTy,0),gep,ci);
1636 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,1));
1637 ci->eraseFromParent();
1645 /// This LibCallOptimization will simplify calls to the "fputs" library
1646 /// function. It looks for cases where the result of fputs is not used and the
1647 /// operation can be reduced to something simpler.
1648 /// @brief Simplify the puts library function.
1649 struct PutsOptimization : public LibCallOptimization {
1651 /// @brief Default Constructor
1652 PutsOptimization() : LibCallOptimization("fputs",
1653 "Number of 'fputs' calls simplified") {}
1655 /// @brief Make sure that the "fputs" function has the right prototype
1656 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1657 // Just make sure this has 2 arguments
1658 return F->arg_size() == 2;
1661 /// @brief Perform the fputs optimization.
1662 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1663 // If the result is used, none of these optimizations work
1664 if (!ci->use_empty())
1667 // All the optimizations depend on the length of the first argument and the
1668 // fact that it is a constant string array. Check that now
1670 if (!getConstantStringLength(ci->getOperand(1), len))
1675 // fputs("",F) -> noop
1679 // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
1680 const Type* FILEptr_type = ci->getOperand(2)->getType();
1681 Function* fputc_func = SLC.get_fputc(FILEptr_type);
1684 LoadInst* loadi = new LoadInst(ci->getOperand(1),
1685 ci->getOperand(1)->getName()+".byte",ci);
1686 CastInst* casti = new SExtInst(loadi, Type::IntTy,
1687 loadi->getName()+".int", ci);
1688 new CallInst(fputc_func,casti,ci->getOperand(2),"",ci);
1693 // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
1694 const Type* FILEptr_type = ci->getOperand(2)->getType();
1695 Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
1698 std::vector<Value*> parms;
1699 parms.push_back(ci->getOperand(1));
1700 parms.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1701 parms.push_back(ConstantInt::get(SLC.getIntPtrType(),1));
1702 parms.push_back(ci->getOperand(2));
1703 new CallInst(fwrite_func,parms,"",ci);
1707 ci->eraseFromParent();
1708 return true; // success
1712 /// This LibCallOptimization will simplify calls to the "isdigit" library
1713 /// function. It simply does range checks the parameter explicitly.
1714 /// @brief Simplify the isdigit library function.
1715 struct isdigitOptimization : public LibCallOptimization {
1717 isdigitOptimization() : LibCallOptimization("isdigit",
1718 "Number of 'isdigit' calls simplified") {}
1720 /// @brief Make sure that the "isdigit" function has the right prototype
1721 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1722 // Just make sure this has 1 argument
1723 return (f->arg_size() == 1);
1726 /// @brief Perform the toascii optimization.
1727 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1728 if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
1729 // isdigit(c) -> 0 or 1, if 'c' is constant
1730 uint64_t val = CI->getZExtValue();
1731 if (val >= '0' && val <='9')
1732 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,1));
1734 ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
1735 ci->eraseFromParent();
1739 // isdigit(c) -> (unsigned)c - '0' <= 9
1740 CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
1741 Type::UIntTy, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
1742 BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
1743 ConstantInt::get(Type::UIntTy,0x30),
1744 ci->getOperand(1)->getName()+".sub",ci);
1745 SetCondInst* setcond_inst = new SetCondInst(Instruction::SetLE,sub_inst,
1746 ConstantInt::get(Type::UIntTy,9),
1747 ci->getOperand(1)->getName()+".cmp",ci);
1748 CastInst* c2 = new ZExtInst(setcond_inst, Type::IntTy,
1749 ci->getOperand(1)->getName()+".isdigit", ci);
1750 ci->replaceAllUsesWith(c2);
1751 ci->eraseFromParent();
1756 struct isasciiOptimization : public LibCallOptimization {
1758 isasciiOptimization()
1759 : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
1761 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1762 return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() &&
1763 F->getReturnType()->isInteger();
1766 /// @brief Perform the isascii optimization.
1767 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1768 // isascii(c) -> (unsigned)c < 128
1769 Value *V = CI->getOperand(1);
1770 if (V->getType()->isSigned())
1771 V = new BitCastInst(V, V->getType()->getUnsignedVersion(), V->getName(),
1773 Value *Cmp = BinaryOperator::createSetLT(V, ConstantInt::get(V->getType(),
1775 V->getName()+".isascii", CI);
1776 if (Cmp->getType() != CI->getType())
1777 Cmp = new BitCastInst(Cmp, CI->getType(), Cmp->getName(), CI);
1778 CI->replaceAllUsesWith(Cmp);
1779 CI->eraseFromParent();
1785 /// This LibCallOptimization will simplify calls to the "toascii" library
1786 /// function. It simply does the corresponding and operation to restrict the
1787 /// range of values to the ASCII character set (0-127).
1788 /// @brief Simplify the toascii library function.
1789 struct ToAsciiOptimization : public LibCallOptimization {
1791 /// @brief Default Constructor
1792 ToAsciiOptimization() : LibCallOptimization("toascii",
1793 "Number of 'toascii' calls simplified") {}
1795 /// @brief Make sure that the "fputs" function has the right prototype
1796 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1797 // Just make sure this has 2 arguments
1798 return (f->arg_size() == 1);
1801 /// @brief Perform the toascii optimization.
1802 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1803 // toascii(c) -> (c & 0x7f)
1804 Value* chr = ci->getOperand(1);
1805 BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
1806 ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
1807 ci->replaceAllUsesWith(and_inst);
1808 ci->eraseFromParent();
1813 /// This LibCallOptimization will simplify calls to the "ffs" library
1814 /// calls which find the first set bit in an int, long, or long long. The
1815 /// optimization is to compute the result at compile time if the argument is
1817 /// @brief Simplify the ffs library function.
1818 struct FFSOptimization : public LibCallOptimization {
1820 /// @brief Subclass Constructor
1821 FFSOptimization(const char* funcName, const char* description)
1822 : LibCallOptimization(funcName, description) {}
1825 /// @brief Default Constructor
1826 FFSOptimization() : LibCallOptimization("ffs",
1827 "Number of 'ffs' calls simplified") {}
1829 /// @brief Make sure that the "ffs" function has the right prototype
1830 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1831 // Just make sure this has 2 arguments
1832 return F->arg_size() == 1 && F->getReturnType() == Type::IntTy;
1835 /// @brief Perform the ffs optimization.
1836 virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
1837 if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
1838 // ffs(cnst) -> bit#
1839 // ffsl(cnst) -> bit#
1840 // ffsll(cnst) -> bit#
1841 uint64_t val = CI->getZExtValue();
1845 while ((val & 1) == 0) {
1850 TheCall->replaceAllUsesWith(ConstantInt::get(Type::IntTy, result));
1851 TheCall->eraseFromParent();
1855 // ffs(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1856 // ffsl(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1857 // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1858 const Type *ArgType = TheCall->getOperand(1)->getType();
1859 ArgType = ArgType->getUnsignedVersion();
1860 const char *CTTZName;
1861 switch (ArgType->getTypeID()) {
1862 default: assert(0 && "Unknown unsigned type!");
1863 case Type::UByteTyID : CTTZName = "llvm.cttz.i8" ; break;
1864 case Type::UShortTyID: CTTZName = "llvm.cttz.i16"; break;
1865 case Type::UIntTyID : CTTZName = "llvm.cttz.i32"; break;
1866 case Type::ULongTyID : CTTZName = "llvm.cttz.i64"; break;
1869 Function *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
1871 Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType,
1872 false/*ZExt*/, "tmp", TheCall);
1873 Value *V2 = new CallInst(F, V, "tmp", TheCall);
1874 V2 = CastInst::createIntegerCast(V2, Type::IntTy, false/*ZExt*/,
1876 V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::IntTy, 1),
1879 BinaryOperator::createSetEQ(V, Constant::getNullValue(V->getType()),
1881 V2 = new SelectInst(Cond, ConstantInt::get(Type::IntTy, 0), V2,
1882 TheCall->getName(), TheCall);
1883 TheCall->replaceAllUsesWith(V2);
1884 TheCall->eraseFromParent();
1889 /// This LibCallOptimization will simplify calls to the "ffsl" library
1890 /// calls. It simply uses FFSOptimization for which the transformation is
1892 /// @brief Simplify the ffsl library function.
1893 struct FFSLOptimization : public FFSOptimization {
1895 /// @brief Default Constructor
1896 FFSLOptimization() : FFSOptimization("ffsl",
1897 "Number of 'ffsl' calls simplified") {}
1901 /// This LibCallOptimization will simplify calls to the "ffsll" library
1902 /// calls. It simply uses FFSOptimization for which the transformation is
1904 /// @brief Simplify the ffsl library function.
1905 struct FFSLLOptimization : public FFSOptimization {
1907 /// @brief Default Constructor
1908 FFSLLOptimization() : FFSOptimization("ffsll",
1909 "Number of 'ffsll' calls simplified") {}
1913 /// This optimizes unary functions that take and return doubles.
1914 struct UnaryDoubleFPOptimizer : public LibCallOptimization {
1915 UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
1916 : LibCallOptimization(Fn, Desc) {}
1918 // Make sure that this function has the right prototype
1919 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1920 return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
1921 F->getReturnType() == Type::DoubleTy;
1924 /// ShrinkFunctionToFloatVersion - If the input to this function is really a
1925 /// float, strength reduce this to a float version of the function,
1926 /// e.g. floor((double)FLT) -> (double)floorf(FLT). This can only be called
1927 /// when the target supports the destination function and where there can be
1928 /// no precision loss.
1929 static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
1930 Function *(SimplifyLibCalls::*FP)()){
1931 if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
1932 if (Cast->getOperand(0)->getType() == Type::FloatTy) {
1933 Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
1935 New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
1936 CI->replaceAllUsesWith(New);
1937 CI->eraseFromParent();
1938 if (Cast->use_empty())
1939 Cast->eraseFromParent();
1947 struct FloorOptimization : public UnaryDoubleFPOptimizer {
1949 : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
1951 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1953 // If this is a float argument passed in, convert to floorf.
1954 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
1957 return false; // opt failed
1961 struct CeilOptimization : public UnaryDoubleFPOptimizer {
1963 : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
1965 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1967 // If this is a float argument passed in, convert to ceilf.
1968 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
1971 return false; // opt failed
1975 struct RoundOptimization : public UnaryDoubleFPOptimizer {
1977 : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
1979 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1981 // If this is a float argument passed in, convert to roundf.
1982 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
1985 return false; // opt failed
1989 struct RintOptimization : public UnaryDoubleFPOptimizer {
1991 : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
1993 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1995 // If this is a float argument passed in, convert to rintf.
1996 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
1999 return false; // opt failed
2003 struct NearByIntOptimization : public UnaryDoubleFPOptimizer {
2004 NearByIntOptimization()
2005 : UnaryDoubleFPOptimizer("nearbyint",
2006 "Number of 'nearbyint' calls simplified") {}
2008 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
2009 #ifdef HAVE_NEARBYINTF
2010 // If this is a float argument passed in, convert to nearbyintf.
2011 if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
2014 return false; // opt failed
2016 } NearByIntOptimizer;
2018 /// A function to compute the length of a null-terminated constant array of
2019 /// integers. This function can't rely on the size of the constant array
2020 /// because there could be a null terminator in the middle of the array.
2021 /// We also have to bail out if we find a non-integer constant initializer
2022 /// of one of the elements or if there is no null-terminator. The logic
2023 /// below checks each of these conditions and will return true only if all
2024 /// conditions are met. In that case, the \p len parameter is set to the length
2025 /// of the null-terminated string. If false is returned, the conditions were
2026 /// not met and len is set to 0.
2027 /// @brief Get the length of a constant string (null-terminated array).
2028 bool getConstantStringLength(Value *V, uint64_t &len, ConstantArray **CA) {
2029 assert(V != 0 && "Invalid args to getConstantStringLength");
2030 len = 0; // make sure we initialize this
2032 // If the value is not a GEP instruction nor a constant expression with a
2033 // GEP instruction, then return false because ConstantArray can't occur
2035 if (GetElementPtrInst* GEPI = dyn_cast<GetElementPtrInst>(V))
2037 else if (ConstantExpr* CE = dyn_cast<ConstantExpr>(V))
2038 if (CE->getOpcode() == Instruction::GetElementPtr)
2045 // Make sure the GEP has exactly three arguments.
2046 if (GEP->getNumOperands() != 3)
2049 // Check to make sure that the first operand of the GEP is an integer and
2050 // has value 0 so that we are sure we're indexing into the initializer.
2051 if (ConstantInt* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
2052 if (!op1->isNullValue())
2057 // Ensure that the second operand is a ConstantInt. If it isn't then this
2058 // GEP is wonky and we're not really sure what were referencing into and
2059 // better of not optimizing it. While we're at it, get the second index
2060 // value. We'll need this later for indexing the ConstantArray.
2061 uint64_t start_idx = 0;
2062 if (ConstantInt* CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
2063 start_idx = CI->getZExtValue();
2067 // The GEP instruction, constant or instruction, must reference a global
2068 // variable that is a constant and is initialized. The referenced constant
2069 // initializer is the array that we'll use for optimization.
2070 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
2071 if (!GV || !GV->isConstant() || !GV->hasInitializer())
2074 // Get the initializer.
2075 Constant* INTLZR = GV->getInitializer();
2077 // Handle the ConstantAggregateZero case
2078 if (isa<ConstantAggregateZero>(INTLZR)) {
2079 // This is a degenerate case. The initializer is constant zero so the
2080 // length of the string must be zero.
2085 // Must be a Constant Array
2086 ConstantArray* A = dyn_cast<ConstantArray>(INTLZR);
2090 // Get the number of elements in the array
2091 uint64_t max_elems = A->getType()->getNumElements();
2093 // Traverse the constant array from start_idx (derived above) which is
2094 // the place the GEP refers to in the array.
2095 for (len = start_idx; len < max_elems; len++) {
2096 if (ConstantInt *CI = dyn_cast<ConstantInt>(A->getOperand(len))) {
2097 // Check for the null terminator
2098 if (CI->isNullValue())
2099 break; // we found end of string
2101 return false; // This array isn't suitable, non-int initializer
2104 if (len >= max_elems)
2105 return false; // This array isn't null terminated
2107 // Subtract out the initial value from the length
2111 return true; // success!
2114 /// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
2115 /// inserting the cast before IP, and return the cast.
2116 /// @brief Cast a value to a "C" string.
2117 Value *CastToCStr(Value *V, Instruction &IP) {
2118 assert(isa<PointerType>(V->getType()) &&
2119 "Can't cast non-pointer type to C string type");
2120 const Type *SBPTy = PointerType::get(Type::SByteTy);
2121 if (V->getType() != SBPTy)
2122 return new BitCastInst(V, SBPTy, V->getName(), &IP);
2127 // Additional cases that we need to add to this file:
2130 // * cbrt(expN(X)) -> expN(x/3)
2131 // * cbrt(sqrt(x)) -> pow(x,1/6)
2132 // * cbrt(sqrt(x)) -> pow(x,1/9)
2135 // * cos(-x) -> cos(x)
2138 // * exp(log(x)) -> x
2141 // * log(exp(x)) -> x
2142 // * log(x**y) -> y*log(x)
2143 // * log(exp(y)) -> y*log(e)
2144 // * log(exp2(y)) -> y*log(2)
2145 // * log(exp10(y)) -> y*log(10)
2146 // * log(sqrt(x)) -> 0.5*log(x)
2147 // * log(pow(x,y)) -> y*log(x)
2149 // lround, lroundf, lroundl:
2150 // * lround(cnst) -> cnst'
2153 // * memcmp(x,y,l) -> cnst
2154 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
2157 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
2158 // (if s is a global constant array)
2161 // * pow(exp(x),y) -> exp(x*y)
2162 // * pow(sqrt(x),y) -> pow(x,y*0.5)
2163 // * pow(pow(x,y),z)-> pow(x,y*z)
2166 // * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
2168 // round, roundf, roundl:
2169 // * round(cnst) -> cnst'
2172 // * signbit(cnst) -> cnst'
2173 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2175 // sqrt, sqrtf, sqrtl:
2176 // * sqrt(expN(x)) -> expN(x*0.5)
2177 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2178 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2181 // * stpcpy(str, "literal") ->
2182 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
2184 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
2185 // (if c is a constant integer and s is a constant string)
2186 // * strrchr(s1,0) -> strchr(s1,0)
2189 // * strncat(x,y,0) -> x
2190 // * strncat(x,y,0) -> x (if strlen(y) = 0)
2191 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
2194 // * strncpy(d,s,0) -> d
2195 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
2196 // (if s and l are constants)
2199 // * strpbrk(s,a) -> offset_in_for(s,a)
2200 // (if s and a are both constant strings)
2201 // * strpbrk(s,"") -> 0
2202 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
2205 // * strspn(s,a) -> const_int (if both args are constant)
2206 // * strspn("",a) -> 0
2207 // * strspn(s,"") -> 0
2208 // * strcspn(s,a) -> const_int (if both args are constant)
2209 // * strcspn("",a) -> 0
2210 // * strcspn(s,"") -> strlen(a)
2213 // * strstr(x,x) -> x
2214 // * strstr(s1,s2) -> offset_of_s2_in(s1)
2215 // (if s1 and s2 are constant strings)
2218 // * tan(atan(x)) -> x
2220 // trunc, truncf, truncl:
2221 // * trunc(cnst) -> cnst'