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/Compiler.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Target/TargetData.h"
32 #include "llvm/Transforms/IPO.h"
35 /// This statistic keeps track of the total number of library calls that have
36 /// been simplified regardless of which call it is.
37 STATISTIC(SimplifiedLibCalls, "Number of library calls simplified");
40 // Forward declarations
41 class LibCallOptimization;
42 class SimplifyLibCalls;
44 /// This list is populated by the constructor for LibCallOptimization class.
45 /// Therefore all subclasses are registered here at static initialization time
46 /// and this list is what the SimplifyLibCalls pass uses to apply the individual
47 /// optimizations to the call sites.
48 /// @brief The list of optimizations deriving from LibCallOptimization
49 static LibCallOptimization *OptList = 0;
51 /// This class is the abstract base class for the set of optimizations that
52 /// corresponds to one library call. The SimplifyLibCalls pass will call the
53 /// ValidateCalledFunction method to ask the optimization if a given Function
54 /// is the kind that the optimization can handle. If the subclass returns true,
55 /// then SImplifyLibCalls will also call the OptimizeCall method to perform,
56 /// or attempt to perform, the optimization(s) for the library call. Otherwise,
57 /// OptimizeCall won't be called. Subclasses are responsible for providing the
58 /// name of the library call (strlen, strcpy, etc.) to the LibCallOptimization
59 /// constructor. This is used to efficiently select which call instructions to
60 /// optimize. The criteria for a "lib call" is "anything with well known
61 /// semantics", typically a library function that is defined by an international
62 /// standard. Because the semantics are well known, the optimizations can
63 /// generally short-circuit actually calling the function if there's a simpler
64 /// way (e.g. strlen(X) can be reduced to a constant if X is a constant global).
65 /// @brief Base class for library call optimizations
66 class VISIBILITY_HIDDEN LibCallOptimization {
67 LibCallOptimization **Prev, *Next;
68 const char *FunctionName; ///< Name of the library call we optimize
70 Statistic occurrences; ///< debug statistic (-debug-only=simplify-libcalls)
73 /// The \p fname argument must be the name of the library function being
74 /// optimized by the subclass.
75 /// @brief Constructor that registers the optimization.
76 LibCallOptimization(const char *FName, const char *Description)
77 : FunctionName(FName) {
80 occurrences.construct("simplify-libcalls", Description);
82 // Register this optimizer in the list of optimizations.
86 if (Next) Next->Prev = &Next;
89 /// getNext - All libcall optimizations are chained together into a list,
90 /// return the next one in the list.
91 LibCallOptimization *getNext() { return Next; }
93 /// @brief Deregister from the optlist
94 virtual ~LibCallOptimization() {
96 if (Next) Next->Prev = Prev;
99 /// The implementation of this function in subclasses should determine if
100 /// \p F is suitable for the optimization. This method is called by
101 /// SimplifyLibCalls::runOnModule to short circuit visiting all the call
102 /// sites of such a function if that function is not suitable in the first
103 /// place. If the called function is suitabe, this method should return true;
104 /// false, otherwise. This function should also perform any lazy
105 /// initialization that the LibCallOptimization needs to do, if its to return
106 /// true. This avoids doing initialization until the optimizer is actually
107 /// going to be called upon to do some optimization.
108 /// @brief Determine if the function is suitable for optimization
109 virtual bool ValidateCalledFunction(
110 const Function* F, ///< The function that is the target of call sites
111 SimplifyLibCalls& SLC ///< The pass object invoking us
114 /// The implementations of this function in subclasses is the heart of the
115 /// SimplifyLibCalls algorithm. Sublcasses of this class implement
116 /// OptimizeCall to determine if (a) the conditions are right for optimizing
117 /// the call and (b) to perform the optimization. If an action is taken
118 /// against ci, the subclass is responsible for returning true and ensuring
119 /// that ci is erased from its parent.
120 /// @brief Optimize a call, if possible.
121 virtual bool OptimizeCall(
122 CallInst* ci, ///< The call instruction that should be optimized.
123 SimplifyLibCalls& SLC ///< The pass object invoking us
126 /// @brief Get the name of the library call being optimized
127 const char *getFunctionName() const { return FunctionName; }
129 /// @brief Called by SimplifyLibCalls to update the occurrences statistic.
132 DEBUG(++occurrences);
137 /// This class is an LLVM Pass that applies each of the LibCallOptimization
138 /// instances to all the call sites in a module, relatively efficiently. The
139 /// purpose of this pass is to provide optimizations for calls to well-known
140 /// functions with well-known semantics, such as those in the c library. The
141 /// class provides the basic infrastructure for handling runOnModule. Whenever
142 /// this pass finds a function call, it asks the appropriate optimizer to
143 /// validate the call (ValidateLibraryCall). If it is validated, then
144 /// the OptimizeCall method is also called.
145 /// @brief A ModulePass for optimizing well-known function calls.
146 class VISIBILITY_HIDDEN SimplifyLibCalls : public ModulePass {
148 /// We need some target data for accurate signature details that are
149 /// target dependent. So we require target data in our AnalysisUsage.
150 /// @brief Require TargetData from AnalysisUsage.
151 virtual void getAnalysisUsage(AnalysisUsage& Info) const {
152 // Ask that the TargetData analysis be performed before us so we can use
154 Info.addRequired<TargetData>();
157 /// For this pass, process all of the function calls in the module, calling
158 /// ValidateLibraryCall and OptimizeCall as appropriate.
159 /// @brief Run all the lib call optimizations on a Module.
160 virtual bool runOnModule(Module &M) {
164 hash_map<std::string, LibCallOptimization*> OptznMap;
165 for (LibCallOptimization *Optzn = OptList; Optzn; Optzn = Optzn->getNext())
166 OptznMap[Optzn->getFunctionName()] = Optzn;
168 // The call optimizations can be recursive. That is, the optimization might
169 // generate a call to another function which can also be optimized. This way
170 // we make the LibCallOptimization instances very specific to the case they
171 // handle. It also means we need to keep running over the function calls in
172 // the module until we don't get any more optimizations possible.
173 bool found_optimization = false;
175 found_optimization = false;
176 for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
177 // All the "well-known" functions are external and have external linkage
178 // because they live in a runtime library somewhere and were (probably)
179 // not compiled by LLVM. So, we only act on external functions that
180 // have external or dllimport linkage and non-empty uses.
181 if (!FI->isDeclaration() ||
182 !(FI->hasExternalLinkage() || FI->hasDLLImportLinkage()) ||
186 // Get the optimization class that pertains to this function
187 hash_map<std::string, LibCallOptimization*>::iterator OMI =
188 OptznMap.find(FI->getName());
189 if (OMI == OptznMap.end()) continue;
191 LibCallOptimization *CO = OMI->second;
193 // Make sure the called function is suitable for the optimization
194 if (!CO->ValidateCalledFunction(FI, *this))
197 // Loop over each of the uses of the function
198 for (Value::use_iterator UI = FI->use_begin(), UE = FI->use_end();
200 // If the use of the function is a call instruction
201 if (CallInst* CI = dyn_cast<CallInst>(*UI++)) {
202 // Do the optimization on the LibCallOptimization.
203 if (CO->OptimizeCall(CI, *this)) {
204 ++SimplifiedLibCalls;
205 found_optimization = result = true;
211 } while (found_optimization);
216 /// @brief Return the *current* module we're working on.
217 Module* getModule() const { return M; }
219 /// @brief Return the *current* target data for the module we're working on.
220 TargetData* getTargetData() const { return TD; }
222 /// @brief Return the size_t type -- syntactic shortcut
223 const Type* getIntPtrType() const { return TD->getIntPtrType(); }
225 /// @brief Return a Function* for the putchar libcall
226 Constant *get_putchar() {
229 M->getOrInsertFunction("putchar", Type::Int32Ty, Type::Int32Ty, NULL);
233 /// @brief Return a Function* for the puts libcall
234 Constant *get_puts() {
236 puts_func = M->getOrInsertFunction("puts", Type::Int32Ty,
237 PointerType::get(Type::Int8Ty),
242 /// @brief Return a Function* for the fputc libcall
243 Constant *get_fputc(const Type* FILEptr_type) {
245 fputc_func = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
250 /// @brief Return a Function* for the fputs libcall
251 Constant *get_fputs(const Type* FILEptr_type) {
253 fputs_func = M->getOrInsertFunction("fputs", Type::Int32Ty,
254 PointerType::get(Type::Int8Ty),
259 /// @brief Return a Function* for the fwrite libcall
260 Constant *get_fwrite(const Type* FILEptr_type) {
262 fwrite_func = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
263 PointerType::get(Type::Int8Ty),
270 /// @brief Return a Function* for the sqrt libcall
271 Constant *get_sqrt() {
273 sqrt_func = M->getOrInsertFunction("sqrt", Type::DoubleTy,
274 Type::DoubleTy, NULL);
278 /// @brief Return a Function* for the strcpy libcall
279 Constant *get_strcpy() {
281 strcpy_func = M->getOrInsertFunction("strcpy",
282 PointerType::get(Type::Int8Ty),
283 PointerType::get(Type::Int8Ty),
284 PointerType::get(Type::Int8Ty),
289 /// @brief Return a Function* for the strlen libcall
290 Constant *get_strlen() {
292 strlen_func = M->getOrInsertFunction("strlen", TD->getIntPtrType(),
293 PointerType::get(Type::Int8Ty),
298 /// @brief Return a Function* for the memchr libcall
299 Constant *get_memchr() {
301 memchr_func = M->getOrInsertFunction("memchr",
302 PointerType::get(Type::Int8Ty),
303 PointerType::get(Type::Int8Ty),
304 Type::Int32Ty, TD->getIntPtrType(),
309 /// @brief Return a Function* for the memcpy libcall
310 Constant *get_memcpy() {
312 const Type *SBP = PointerType::get(Type::Int8Ty);
313 const char *N = TD->getIntPtrType() == Type::Int32Ty ?
314 "llvm.memcpy.i32" : "llvm.memcpy.i64";
315 memcpy_func = M->getOrInsertFunction(N, Type::VoidTy, SBP, SBP,
316 TD->getIntPtrType(), Type::Int32Ty,
322 Constant *getUnaryFloatFunction(const char *Name, Constant *&Cache) {
324 Cache = M->getOrInsertFunction(Name, Type::FloatTy, Type::FloatTy, NULL);
328 Constant *get_floorf() { return getUnaryFloatFunction("floorf", floorf_func);}
329 Constant *get_ceilf() { return getUnaryFloatFunction( "ceilf", ceilf_func);}
330 Constant *get_roundf() { return getUnaryFloatFunction("roundf", roundf_func);}
331 Constant *get_rintf() { return getUnaryFloatFunction( "rintf", rintf_func);}
332 Constant *get_nearbyintf() { return getUnaryFloatFunction("nearbyintf",
335 /// @brief Reset our cached data for a new Module
336 void reset(Module& mod) {
338 TD = &getAnalysis<TargetData>();
357 /// Caches for function pointers.
358 Constant *putchar_func, *puts_func;
359 Constant *fputc_func, *fputs_func, *fwrite_func;
360 Constant *memcpy_func, *memchr_func;
362 Constant *strcpy_func, *strlen_func;
363 Constant *floorf_func, *ceilf_func, *roundf_func;
364 Constant *rintf_func, *nearbyintf_func;
365 Module *M; ///< Cached Module
366 TargetData *TD; ///< Cached TargetData
370 RegisterPass<SimplifyLibCalls>
371 X("simplify-libcalls", "Simplify well-known library calls");
373 } // anonymous namespace
375 // The only public symbol in this file which just instantiates the pass object
376 ModulePass *llvm::createSimplifyLibCallsPass() {
377 return new SimplifyLibCalls();
380 // Classes below here, in the anonymous namespace, are all subclasses of the
381 // LibCallOptimization class, each implementing all optimizations possible for a
382 // single well-known library call. Each has a static singleton instance that
383 // auto registers it into the "optlist" global above.
386 // Forward declare utility functions.
387 static bool getConstantStringLength(Value* V, uint64_t& len,
388 ConstantArray** A = 0 );
389 static Value *CastToCStr(Value *V, Instruction &IP);
391 /// This LibCallOptimization will find instances of a call to "exit" that occurs
392 /// within the "main" function and change it to a simple "ret" instruction with
393 /// the same value passed to the exit function. When this is done, it splits the
394 /// basic block at the exit(3) call and deletes the call instruction.
395 /// @brief Replace calls to exit in main with a simple return
396 struct VISIBILITY_HIDDEN ExitInMainOptimization : public LibCallOptimization {
397 ExitInMainOptimization() : LibCallOptimization("exit",
398 "Number of 'exit' calls simplified") {}
400 // Make sure the called function looks like exit (int argument, int return
401 // type, external linkage, not varargs).
402 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
403 return F->arg_size() >= 1 && F->arg_begin()->getType()->isInteger();
406 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
407 // To be careful, we check that the call to exit is coming from "main", that
408 // main has external linkage, and the return type of main and the argument
409 // to exit have the same type.
410 Function *from = ci->getParent()->getParent();
411 if (from->hasExternalLinkage())
412 if (from->getReturnType() == ci->getOperand(1)->getType())
413 if (from->getName() == "main") {
414 // Okay, time to actually do the optimization. First, get the basic
415 // block of the call instruction
416 BasicBlock* bb = ci->getParent();
418 // Create a return instruction that we'll replace the call with.
419 // Note that the argument of the return is the argument of the call
421 new ReturnInst(ci->getOperand(1), ci);
423 // Split the block at the call instruction which places it in a new
425 bb->splitBasicBlock(ci);
427 // The block split caused a branch instruction to be inserted into
428 // the end of the original block, right after the return instruction
429 // that we put there. That's not a valid block, so delete the branch
431 bb->getInstList().pop_back();
433 // Now we can finally get rid of the call instruction which now lives
434 // in the new basic block.
435 ci->eraseFromParent();
437 // Optimization succeeded, return true.
440 // We didn't pass the criteria for this optimization so return false
443 } ExitInMainOptimizer;
445 /// This LibCallOptimization will simplify a call to the strcat library
446 /// function. The simplification is possible only if the string being
447 /// concatenated is a constant array or a constant expression that results in
448 /// a constant string. In this case we can replace it with strlen + llvm.memcpy
449 /// of the constant string. Both of these calls are further reduced, if possible
450 /// on subsequent passes.
451 /// @brief Simplify the strcat library function.
452 struct VISIBILITY_HIDDEN StrCatOptimization : public LibCallOptimization {
454 /// @brief Default constructor
455 StrCatOptimization() : LibCallOptimization("strcat",
456 "Number of 'strcat' calls simplified") {}
460 /// @brief Make sure that the "strcat" function has the right prototype
461 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
462 if (f->getReturnType() == PointerType::get(Type::Int8Ty))
463 if (f->arg_size() == 2)
465 Function::const_arg_iterator AI = f->arg_begin();
466 if (AI++->getType() == PointerType::get(Type::Int8Ty))
467 if (AI->getType() == PointerType::get(Type::Int8Ty))
469 // Indicate this is a suitable call type.
476 /// @brief Optimize the strcat library function
477 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
478 // Extract some information from the instruction
479 Value* dest = ci->getOperand(1);
480 Value* src = ci->getOperand(2);
482 // Extract the initializer (while making numerous checks) from the
483 // source operand of the call to strcat. If we get null back, one of
484 // a variety of checks in get_GVInitializer failed
486 if (!getConstantStringLength(src,len))
489 // Handle the simple, do-nothing case
491 ci->replaceAllUsesWith(dest);
492 ci->eraseFromParent();
496 // Increment the length because we actually want to memcpy the null
497 // terminator as well.
500 // We need to find the end of the destination string. That's where the
501 // memory is to be moved to. We just generate a call to strlen (further
502 // optimized in another pass). Note that the SLC.get_strlen() call
503 // caches the Function* for us.
504 CallInst* strlen_inst =
505 new CallInst(SLC.get_strlen(), dest, dest->getName()+".len",ci);
507 // Now that we have the destination's length, we must index into the
508 // destination's pointer to get the actual memcpy destination (end of
509 // the string .. we're concatenating).
510 GetElementPtrInst* gep =
511 new GetElementPtrInst(dest, strlen_inst, 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::Int32Ty,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 VISIBILITY_HIDDEN 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::Int8Ty) &&
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));
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 Constant *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 Value* Idx = ConstantInt::get(Type::Int64Ty,offset);
600 GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1), Idx,
601 ci->getOperand(1)->getName()+".strchr",ci);
602 ci->replaceAllUsesWith(GEP);
604 ci->replaceAllUsesWith(
605 ConstantPointerNull::get(PointerType::get(Type::Int8Ty)));
607 ci->eraseFromParent();
612 /// This LibCallOptimization will simplify a call to the strcmp library
613 /// function. It optimizes out cases where one or both arguments are constant
614 /// and the result can be determined statically.
615 /// @brief Simplify the strcmp library function.
616 struct VISIBILITY_HIDDEN StrCmpOptimization : public LibCallOptimization {
618 StrCmpOptimization() : LibCallOptimization("strcmp",
619 "Number of 'strcmp' calls simplified") {}
621 /// @brief Make sure that the "strcmp" function has the right prototype
622 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
623 return F->getReturnType() == Type::Int32Ty && F->arg_size() == 2;
626 /// @brief Perform the strcmp optimization
627 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
628 // First, check to see if src and destination are the same. If they are,
629 // then the optimization is to replace the CallInst with a constant 0
630 // because the call is a no-op.
631 Value* s1 = ci->getOperand(1);
632 Value* s2 = ci->getOperand(2);
635 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
636 ci->eraseFromParent();
640 bool isstr_1 = false;
643 if (getConstantStringLength(s1,len_1,&A1)) {
646 // strcmp("",x) -> *x
648 new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
650 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
651 ci->getName()+".int", ci);
652 ci->replaceAllUsesWith(cast);
653 ci->eraseFromParent();
658 bool isstr_2 = false;
661 if (getConstantStringLength(s2, len_2, &A2)) {
664 // strcmp(x,"") -> *x
666 new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
668 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
669 ci->getName()+".int", ci);
670 ci->replaceAllUsesWith(cast);
671 ci->eraseFromParent();
676 if (isstr_1 && isstr_2) {
677 // strcmp(x,y) -> cnst (if both x and y are constant strings)
678 std::string str1 = A1->getAsString();
679 std::string str2 = A2->getAsString();
680 int result = strcmp(str1.c_str(), str2.c_str());
681 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
682 ci->eraseFromParent();
689 /// This LibCallOptimization will simplify a call to the strncmp library
690 /// function. It optimizes out cases where one or both arguments are constant
691 /// and the result can be determined statically.
692 /// @brief Simplify the strncmp library function.
693 struct VISIBILITY_HIDDEN StrNCmpOptimization : public LibCallOptimization {
695 StrNCmpOptimization() : LibCallOptimization("strncmp",
696 "Number of 'strncmp' calls simplified") {}
698 /// @brief Make sure that the "strncmp" function has the right prototype
699 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
700 if (f->getReturnType() == Type::Int32Ty && f->arg_size() == 3)
705 /// @brief Perform the strncpy optimization
706 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
707 // First, check to see if src and destination are the same. If they are,
708 // then the optimization is to replace the CallInst with a constant 0
709 // because the call is a no-op.
710 Value* s1 = ci->getOperand(1);
711 Value* s2 = ci->getOperand(2);
713 // strncmp(x,x,l) -> 0
714 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
715 ci->eraseFromParent();
719 // Check the length argument, if it is Constant zero then the strings are
721 uint64_t len_arg = 0;
722 bool len_arg_is_const = false;
723 if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
724 len_arg_is_const = true;
725 len_arg = len_CI->getZExtValue();
727 // strncmp(x,y,0) -> 0
728 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
729 ci->eraseFromParent();
734 bool isstr_1 = false;
737 if (getConstantStringLength(s1, len_1, &A1)) {
740 // strncmp("",x) -> *x
741 LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
743 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
744 ci->getName()+".int", ci);
745 ci->replaceAllUsesWith(cast);
746 ci->eraseFromParent();
751 bool isstr_2 = false;
754 if (getConstantStringLength(s2,len_2,&A2)) {
757 // strncmp(x,"") -> *x
758 LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
760 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
761 ci->getName()+".int", ci);
762 ci->replaceAllUsesWith(cast);
763 ci->eraseFromParent();
768 if (isstr_1 && isstr_2 && len_arg_is_const) {
769 // strncmp(x,y,const) -> constant
770 std::string str1 = A1->getAsString();
771 std::string str2 = A2->getAsString();
772 int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
773 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
774 ci->eraseFromParent();
781 /// This LibCallOptimization will simplify a call to the strcpy library
782 /// function. Two optimizations are possible:
783 /// (1) If src and dest are the same and not volatile, just return dest
784 /// (2) If the src is a constant then we can convert to llvm.memmove
785 /// @brief Simplify the strcpy library function.
786 struct VISIBILITY_HIDDEN StrCpyOptimization : public LibCallOptimization {
788 StrCpyOptimization() : LibCallOptimization("strcpy",
789 "Number of 'strcpy' calls simplified") {}
791 /// @brief Make sure that the "strcpy" function has the right prototype
792 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
793 if (f->getReturnType() == PointerType::get(Type::Int8Ty))
794 if (f->arg_size() == 2) {
795 Function::const_arg_iterator AI = f->arg_begin();
796 if (AI++->getType() == PointerType::get(Type::Int8Ty))
797 if (AI->getType() == PointerType::get(Type::Int8Ty)) {
798 // Indicate this is a suitable call type.
805 /// @brief Perform the strcpy optimization
806 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
807 // First, check to see if src and destination are the same. If they are,
808 // then the optimization is to replace the CallInst with the destination
809 // because the call is a no-op. Note that this corresponds to the
810 // degenerate strcpy(X,X) case which should have "undefined" results
811 // according to the C specification. However, it occurs sometimes and
812 // we optimize it as a no-op.
813 Value* dest = ci->getOperand(1);
814 Value* src = ci->getOperand(2);
816 ci->replaceAllUsesWith(dest);
817 ci->eraseFromParent();
821 // Get the length of the constant string referenced by the second operand,
822 // the "src" parameter. Fail the optimization if we can't get the length
823 // (note that getConstantStringLength does lots of checks to make sure this
826 if (!getConstantStringLength(ci->getOperand(2),len))
829 // If the constant string's length is zero we can optimize this by just
830 // doing a store of 0 at the first byte of the destination
832 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
833 ci->replaceAllUsesWith(dest);
834 ci->eraseFromParent();
838 // Increment the length because we actually want to memcpy the null
839 // terminator as well.
842 // We have enough information to now generate the memcpy call to
843 // do the concatenation for us.
844 std::vector<Value*> vals;
845 vals.push_back(dest); // destination
846 vals.push_back(src); // source
847 vals.push_back(ConstantInt::get(SLC.getIntPtrType(),len)); // length
848 vals.push_back(ConstantInt::get(Type::Int32Ty,1)); // alignment
849 new CallInst(SLC.get_memcpy(), vals, "", ci);
851 // Finally, substitute the first operand of the strcat call for the
852 // strcat call itself since strcat returns its first operand; and,
853 // kill the strcat CallInst.
854 ci->replaceAllUsesWith(dest);
855 ci->eraseFromParent();
860 /// This LibCallOptimization will simplify a call to the strlen library
861 /// function by replacing it with a constant value if the string provided to
862 /// it is a constant array.
863 /// @brief Simplify the strlen library function.
864 struct VISIBILITY_HIDDEN StrLenOptimization : public LibCallOptimization {
865 StrLenOptimization() : LibCallOptimization("strlen",
866 "Number of 'strlen' calls simplified") {}
868 /// @brief Make sure that the "strlen" function has the right prototype
869 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
871 if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
872 if (f->arg_size() == 1)
873 if (Function::const_arg_iterator AI = f->arg_begin())
874 if (AI->getType() == PointerType::get(Type::Int8Ty))
879 /// @brief Perform the strlen optimization
880 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
882 // Make sure we're dealing with an sbyte* here.
883 Value* str = ci->getOperand(1);
884 if (str->getType() != PointerType::get(Type::Int8Ty))
887 // Does the call to strlen have exactly one use?
889 // Is that single use a icmp operator?
890 if (ICmpInst* bop = dyn_cast<ICmpInst>(ci->use_back()))
891 // Is it compared against a constant integer?
892 if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
894 // Get the value the strlen result is compared to
895 uint64_t val = CI->getZExtValue();
897 // If its compared against length 0 with == or !=
899 (bop->getPredicate() == ICmpInst::ICMP_EQ ||
900 bop->getPredicate() == ICmpInst::ICMP_NE))
902 // strlen(x) != 0 -> *x != 0
903 // strlen(x) == 0 -> *x == 0
904 LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
905 ICmpInst* rbop = new ICmpInst(bop->getPredicate(), load,
906 ConstantInt::get(Type::Int8Ty,0),
907 bop->getName()+".strlen", ci);
908 bop->replaceAllUsesWith(rbop);
909 bop->eraseFromParent();
910 ci->eraseFromParent();
915 // Get the length of the constant string operand
917 if (!getConstantStringLength(ci->getOperand(1),len))
920 // strlen("xyz") -> 3 (for example)
921 const Type *Ty = SLC.getTargetData()->getIntPtrType();
922 ci->replaceAllUsesWith(ConstantInt::get(Ty, len));
924 ci->eraseFromParent();
929 /// IsOnlyUsedInEqualsComparison - Return true if it only matters that the value
930 /// is equal or not-equal to zero.
931 static bool IsOnlyUsedInEqualsZeroComparison(Instruction *I) {
932 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
934 Instruction *User = cast<Instruction>(*UI);
935 if (ICmpInst *IC = dyn_cast<ICmpInst>(User)) {
936 if ((IC->getPredicate() == ICmpInst::ICMP_NE ||
937 IC->getPredicate() == ICmpInst::ICMP_EQ) &&
938 isa<Constant>(IC->getOperand(1)) &&
939 cast<Constant>(IC->getOperand(1))->isNullValue())
941 } else if (CastInst *CI = dyn_cast<CastInst>(User))
942 if (CI->getType() == Type::Int1Ty)
944 // Unknown instruction.
950 /// This memcmpOptimization will simplify a call to the memcmp library
952 struct VISIBILITY_HIDDEN memcmpOptimization : public LibCallOptimization {
953 /// @brief Default Constructor
955 : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
957 /// @brief Make sure that the "memcmp" function has the right prototype
958 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
959 Function::const_arg_iterator AI = F->arg_begin();
960 if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
961 if (!isa<PointerType>((++AI)->getType())) return false;
962 if (!(++AI)->getType()->isInteger()) return false;
963 if (!F->getReturnType()->isInteger()) return false;
967 /// Because of alignment and instruction information that we don't have, we
968 /// leave the bulk of this to the code generators.
970 /// Note that we could do much more if we could force alignment on otherwise
971 /// small aligned allocas, or if we could indicate that loads have a small
973 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
974 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
976 // If the two operands are the same, return zero.
978 // memcmp(s,s,x) -> 0
979 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
980 CI->eraseFromParent();
984 // Make sure we have a constant length.
985 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
986 if (!LenC) return false;
987 uint64_t Len = LenC->getZExtValue();
989 // If the length is zero, this returns 0.
992 // memcmp(s1,s2,0) -> 0
993 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
994 CI->eraseFromParent();
997 // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
998 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
999 CastInst *Op1Cast = CastInst::create(
1000 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1001 CastInst *Op2Cast = CastInst::create(
1002 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1003 Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
1004 Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
1005 Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
1006 if (RV->getType() != CI->getType())
1007 RV = CastInst::createIntegerCast(RV, CI->getType(), false,
1009 CI->replaceAllUsesWith(RV);
1010 CI->eraseFromParent();
1014 if (IsOnlyUsedInEqualsZeroComparison(CI)) {
1015 // TODO: IF both are aligned, use a short load/compare.
1017 // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
1018 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1019 CastInst *Op1Cast = CastInst::create(
1020 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1021 CastInst *Op2Cast = CastInst::create(
1022 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1023 Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
1024 Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
1025 Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
1026 CI->getName()+".d1", CI);
1027 Constant *One = ConstantInt::get(Type::Int32Ty, 1);
1028 Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
1029 Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
1030 Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
1031 Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
1032 Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
1033 CI->getName()+".d1", CI);
1034 Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
1035 if (Or->getType() != CI->getType())
1036 Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/,
1038 CI->replaceAllUsesWith(Or);
1039 CI->eraseFromParent();
1052 /// This LibCallOptimization will simplify a call to the memcpy library
1053 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1054 /// bytes depending on the length of the string and the alignment. Additional
1055 /// optimizations are possible in code generation (sequence of immediate store)
1056 /// @brief Simplify the memcpy library function.
1057 struct VISIBILITY_HIDDEN LLVMMemCpyMoveOptzn : public LibCallOptimization {
1058 LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
1059 : LibCallOptimization(fname, desc) {}
1061 /// @brief Make sure that the "memcpy" function has the right prototype
1062 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
1063 // Just make sure this has 4 arguments per LLVM spec.
1064 return (f->arg_size() == 4);
1067 /// Because of alignment and instruction information that we don't have, we
1068 /// leave the bulk of this to the code generators. The optimization here just
1069 /// deals with a few degenerate cases where the length of the string and the
1070 /// alignment match the sizes of our intrinsic types so we can do a load and
1071 /// store instead of the memcpy call.
1072 /// @brief Perform the memcpy optimization.
1073 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
1074 // Make sure we have constant int values to work with
1075 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1078 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1082 // If the length is larger than the alignment, we can't optimize
1083 uint64_t len = LEN->getZExtValue();
1084 uint64_t alignment = ALIGN->getZExtValue();
1086 alignment = 1; // Alignment 0 is identity for alignment 1
1087 if (len > alignment)
1090 // Get the type we will cast to, based on size of the string
1091 Value* dest = ci->getOperand(1);
1092 Value* src = ci->getOperand(2);
1093 const Type* castType = 0;
1097 // memcpy(d,s,0,a) -> noop
1098 ci->eraseFromParent();
1100 case 1: castType = Type::Int8Ty; break;
1101 case 2: castType = Type::Int16Ty; break;
1102 case 4: castType = Type::Int32Ty; break;
1103 case 8: castType = Type::Int64Ty; break;
1108 // Cast source and dest to the right sized primitive and then load/store
1109 CastInst* SrcCast = CastInst::create(Instruction::BitCast,
1110 src, PointerType::get(castType), src->getName()+".cast", ci);
1111 CastInst* DestCast = CastInst::create(Instruction::BitCast,
1112 dest, PointerType::get(castType),dest->getName()+".cast", ci);
1113 LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
1114 new StoreInst(LI, DestCast, ci);
1115 ci->eraseFromParent();
1120 /// This LibCallOptimization will simplify a call to the memcpy/memmove library
1122 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
1123 "Number of 'llvm.memcpy' calls simplified");
1124 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
1125 "Number of 'llvm.memcpy' calls simplified");
1126 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
1127 "Number of 'llvm.memmove' calls simplified");
1128 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
1129 "Number of 'llvm.memmove' calls simplified");
1131 /// This LibCallOptimization will simplify a call to the memset library
1132 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1133 /// bytes depending on the length argument.
1134 struct VISIBILITY_HIDDEN LLVMMemSetOptimization : public LibCallOptimization {
1135 /// @brief Default Constructor
1136 LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
1137 "Number of 'llvm.memset' calls simplified") {}
1139 /// @brief Make sure that the "memset" function has the right prototype
1140 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
1141 // Just make sure this has 3 arguments per LLVM spec.
1142 return F->arg_size() == 4;
1145 /// Because of alignment and instruction information that we don't have, we
1146 /// leave the bulk of this to the code generators. The optimization here just
1147 /// deals with a few degenerate cases where the length parameter is constant
1148 /// and the alignment matches the sizes of our intrinsic types so we can do
1149 /// store instead of the memcpy call. Other calls are transformed into the
1150 /// llvm.memset intrinsic.
1151 /// @brief Perform the memset optimization.
1152 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
1153 // Make sure we have constant int values to work with
1154 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1157 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1161 // Extract the length and alignment
1162 uint64_t len = LEN->getZExtValue();
1163 uint64_t alignment = ALIGN->getZExtValue();
1165 // Alignment 0 is identity for alignment 1
1169 // If the length is zero, this is a no-op
1171 // memset(d,c,0,a) -> noop
1172 ci->eraseFromParent();
1176 // If the length is larger than the alignment, we can't optimize
1177 if (len > alignment)
1180 // Make sure we have a constant ubyte to work with so we can extract
1181 // the value to be filled.
1182 ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
1185 if (FILL->getType() != Type::Int8Ty)
1188 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
1190 // Extract the fill character
1191 uint64_t fill_char = FILL->getZExtValue();
1192 uint64_t fill_value = fill_char;
1194 // Get the type we will cast to, based on size of memory area to fill, and
1195 // and the value we will store there.
1196 Value* dest = ci->getOperand(1);
1197 const Type* castType = 0;
1200 castType = Type::Int8Ty;
1203 castType = Type::Int16Ty;
1204 fill_value |= fill_char << 8;
1207 castType = Type::Int32Ty;
1208 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1211 castType = Type::Int64Ty;
1212 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1213 fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
1214 fill_value |= fill_char << 56;
1220 // Cast dest to the right sized primitive and then load/store
1221 CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType),
1222 dest->getName()+".cast", ci);
1223 new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
1224 ci->eraseFromParent();
1229 LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
1230 LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
1233 /// This LibCallOptimization will simplify calls to the "pow" library
1234 /// function. It looks for cases where the result of pow is well known and
1235 /// substitutes the appropriate value.
1236 /// @brief Simplify the pow library function.
1237 struct VISIBILITY_HIDDEN PowOptimization : public LibCallOptimization {
1239 /// @brief Default Constructor
1240 PowOptimization() : LibCallOptimization("pow",
1241 "Number of 'pow' calls simplified") {}
1243 /// @brief Make sure that the "pow" function has the right prototype
1244 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1245 // Just make sure this has 2 arguments
1246 return (f->arg_size() == 2);
1249 /// @brief Perform the pow optimization.
1250 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1251 const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
1252 Value* base = ci->getOperand(1);
1253 Value* expn = ci->getOperand(2);
1254 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
1255 double Op1V = Op1->getValue();
1257 // pow(1.0,x) -> 1.0
1258 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1259 ci->eraseFromParent();
1262 } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
1263 double Op2V = Op2->getValue();
1265 // pow(x,0.0) -> 1.0
1266 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1267 ci->eraseFromParent();
1269 } else if (Op2V == 0.5) {
1270 // pow(x,0.5) -> sqrt(x)
1271 CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
1272 ci->getName()+".pow",ci);
1273 ci->replaceAllUsesWith(sqrt_inst);
1274 ci->eraseFromParent();
1276 } else if (Op2V == 1.0) {
1278 ci->replaceAllUsesWith(base);
1279 ci->eraseFromParent();
1281 } else if (Op2V == -1.0) {
1282 // pow(x,-1.0) -> 1.0/x
1283 BinaryOperator* div_inst= BinaryOperator::createFDiv(
1284 ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
1285 ci->replaceAllUsesWith(div_inst);
1286 ci->eraseFromParent();
1290 return false; // opt failed
1294 /// This LibCallOptimization will simplify calls to the "printf" library
1295 /// function. It looks for cases where the result of printf is not used and the
1296 /// operation can be reduced to something simpler.
1297 /// @brief Simplify the printf library function.
1298 struct VISIBILITY_HIDDEN PrintfOptimization : public LibCallOptimization {
1300 /// @brief Default Constructor
1301 PrintfOptimization() : LibCallOptimization("printf",
1302 "Number of 'printf' calls simplified") {}
1304 /// @brief Make sure that the "printf" function has the right prototype
1305 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1306 // Just make sure this has at least 1 arguments
1307 return (f->arg_size() >= 1);
1310 /// @brief Perform the printf optimization.
1311 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1312 // If the call has more than 2 operands, we can't optimize it
1313 if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
1316 // If the result of the printf call is used, none of these optimizations
1318 if (!ci->use_empty())
1321 // All the optimizations depend on the length of the first argument and the
1322 // fact that it is a constant string array. Check that now
1324 ConstantArray* CA = 0;
1325 if (!getConstantStringLength(ci->getOperand(1), len, &CA))
1328 if (len != 2 && len != 3)
1331 // The first character has to be a %
1332 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1333 if (CI->getZExtValue() != '%')
1336 // Get the second character and switch on its value
1337 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1338 switch (CI->getZExtValue()) {
1342 dyn_cast<ConstantInt>(CA->getOperand(2))->getZExtValue() != '\n')
1345 // printf("%s\n",str) -> puts(str)
1346 std::vector<Value*> args;
1347 new CallInst(SLC.get_puts(), CastToCStr(ci->getOperand(2), *ci),
1349 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1354 // printf("%c",c) -> putchar(c)
1358 CastInst *Char = CastInst::createSExtOrBitCast(
1359 ci->getOperand(2), Type::Int32Ty, CI->getName()+".int", ci);
1360 new CallInst(SLC.get_putchar(), Char, "", ci);
1361 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, 1));
1367 ci->eraseFromParent();
1372 /// This LibCallOptimization will simplify calls to the "fprintf" library
1373 /// function. It looks for cases where the result of fprintf is not used and the
1374 /// operation can be reduced to something simpler.
1375 /// @brief Simplify the fprintf library function.
1376 struct VISIBILITY_HIDDEN FPrintFOptimization : public LibCallOptimization {
1378 /// @brief Default Constructor
1379 FPrintFOptimization() : LibCallOptimization("fprintf",
1380 "Number of 'fprintf' calls simplified") {}
1382 /// @brief Make sure that the "fprintf" function has the right prototype
1383 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1384 // Just make sure this has at least 2 arguments
1385 return (f->arg_size() >= 2);
1388 /// @brief Perform the fprintf optimization.
1389 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1390 // If the call has more than 3 operands, we can't optimize it
1391 if (ci->getNumOperands() > 4 || ci->getNumOperands() <= 2)
1394 // If the result of the fprintf call is used, none of these optimizations
1396 if (!ci->use_empty())
1399 // All the optimizations depend on the length of the second argument and the
1400 // fact that it is a constant string array. Check that now
1402 ConstantArray* CA = 0;
1403 if (!getConstantStringLength(ci->getOperand(2), len, &CA))
1406 if (ci->getNumOperands() == 3) {
1407 // Make sure there's no % in the constant array
1408 for (unsigned i = 0; i < len; ++i) {
1409 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1410 // Check for the null terminator
1411 if (CI->getZExtValue() == '%')
1412 return false; // we found end of string
1418 // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
1419 const Type* FILEptr_type = ci->getOperand(1)->getType();
1421 // Make sure that the fprintf() and fwrite() functions both take the
1422 // same type of char pointer.
1423 if (ci->getOperand(2)->getType() != PointerType::get(Type::Int8Ty))
1426 std::vector<Value*> args;
1427 args.push_back(ci->getOperand(2));
1428 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1429 args.push_back(ConstantInt::get(SLC.getIntPtrType(),1));
1430 args.push_back(ci->getOperand(1));
1431 new CallInst(SLC.get_fwrite(FILEptr_type), args, ci->getName(), ci);
1432 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1433 ci->eraseFromParent();
1437 // The remaining optimizations require the format string to be length 2
1442 // The first character has to be a %
1443 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1444 if (CI->getZExtValue() != '%')
1447 // Get the second character and switch on its value
1448 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1449 switch (CI->getZExtValue()) {
1453 ConstantArray* CA = 0;
1454 if (getConstantStringLength(ci->getOperand(3), len, &CA)) {
1455 // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
1456 const Type* FILEptr_type = ci->getOperand(1)->getType();
1457 std::vector<Value*> args;
1458 args.push_back(CastToCStr(ci->getOperand(3), *ci));
1459 args.push_back(ConstantInt::get(SLC.getIntPtrType(), len));
1460 args.push_back(ConstantInt::get(SLC.getIntPtrType(), 1));
1461 args.push_back(ci->getOperand(1));
1462 new CallInst(SLC.get_fwrite(FILEptr_type), args, ci->getName(), ci);
1463 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1465 // fprintf(file,"%s",str) -> fputs(str,file)
1466 const Type* FILEptr_type = ci->getOperand(1)->getType();
1467 new CallInst(SLC.get_fputs(FILEptr_type),
1468 CastToCStr(ci->getOperand(3), *ci),
1469 ci->getOperand(1), ci->getName(),ci);
1470 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1476 // fprintf(file,"%c",c) -> fputc(c,file)
1477 const Type* FILEptr_type = ci->getOperand(1)->getType();
1478 CastInst* cast = CastInst::createSExtOrBitCast(
1479 ci->getOperand(3), Type::Int32Ty, CI->getName()+".int", ci);
1480 new CallInst(SLC.get_fputc(FILEptr_type), cast,ci->getOperand(1),"",ci);
1481 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1487 ci->eraseFromParent();
1492 /// This LibCallOptimization will simplify calls to the "sprintf" library
1493 /// function. It looks for cases where the result of sprintf is not used and the
1494 /// operation can be reduced to something simpler.
1495 /// @brief Simplify the sprintf library function.
1496 struct VISIBILITY_HIDDEN SPrintFOptimization : public LibCallOptimization {
1498 /// @brief Default Constructor
1499 SPrintFOptimization() : LibCallOptimization("sprintf",
1500 "Number of 'sprintf' calls simplified") {}
1502 /// @brief Make sure that the "fprintf" function has the right prototype
1503 virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
1504 // Just make sure this has at least 2 arguments
1505 return (f->getReturnType() == Type::Int32Ty && f->arg_size() >= 2);
1508 /// @brief Perform the sprintf optimization.
1509 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1510 // If the call has more than 3 operands, we can't optimize it
1511 if (ci->getNumOperands() > 4 || ci->getNumOperands() < 3)
1514 // All the optimizations depend on the length of the second argument and the
1515 // fact that it is a constant string array. Check that now
1517 ConstantArray* CA = 0;
1518 if (!getConstantStringLength(ci->getOperand(2), len, &CA))
1521 if (ci->getNumOperands() == 3) {
1523 // If the length is 0, we just need to store a null byte
1524 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
1525 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1526 ci->eraseFromParent();
1530 // Make sure there's no % in the constant array
1531 for (unsigned i = 0; i < len; ++i) {
1532 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1533 // Check for the null terminator
1534 if (CI->getZExtValue() == '%')
1535 return false; // we found a %, can't optimize
1537 return false; // initializer is not constant int, can't optimize
1541 // Increment length because we want to copy the null byte too
1544 // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
1545 std::vector<Value*> args;
1546 args.push_back(ci->getOperand(1));
1547 args.push_back(ci->getOperand(2));
1548 args.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1549 args.push_back(ConstantInt::get(Type::Int32Ty,1));
1550 new CallInst(SLC.get_memcpy(), args, "", ci);
1551 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1552 ci->eraseFromParent();
1556 // The remaining optimizations require the format string to be length 2
1561 // The first character has to be a %
1562 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1563 if (CI->getZExtValue() != '%')
1566 // Get the second character and switch on its value
1567 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1568 switch (CI->getZExtValue()) {
1570 // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1571 Value *Len = new CallInst(SLC.get_strlen(),
1572 CastToCStr(ci->getOperand(3), *ci),
1573 ci->getOperand(3)->getName()+".len", ci);
1574 Value *Len1 = BinaryOperator::createAdd(Len,
1575 ConstantInt::get(Len->getType(), 1),
1576 Len->getName()+"1", ci);
1577 if (Len1->getType() != SLC.getIntPtrType())
1578 Len1 = CastInst::createIntegerCast(Len1, SLC.getIntPtrType(), false,
1579 Len1->getName(), ci);
1580 std::vector<Value*> args;
1581 args.push_back(CastToCStr(ci->getOperand(1), *ci));
1582 args.push_back(CastToCStr(ci->getOperand(3), *ci));
1583 args.push_back(Len1);
1584 args.push_back(ConstantInt::get(Type::Int32Ty,1));
1585 new CallInst(SLC.get_memcpy(), args, "", ci);
1587 // The strlen result is the unincremented number of bytes in the string.
1588 if (!ci->use_empty()) {
1589 if (Len->getType() != ci->getType())
1590 Len = CastInst::createIntegerCast(Len, ci->getType(), false,
1591 Len->getName(), ci);
1592 ci->replaceAllUsesWith(Len);
1594 ci->eraseFromParent();
1598 // sprintf(dest,"%c",chr) -> store chr, dest
1599 CastInst* cast = CastInst::createTruncOrBitCast(
1600 ci->getOperand(3), Type::Int8Ty, "char", ci);
1601 new StoreInst(cast, ci->getOperand(1), ci);
1602 GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
1603 ConstantInt::get(Type::Int32Ty,1),ci->getOperand(1)->getName()+".end",
1605 new StoreInst(ConstantInt::get(Type::Int8Ty,0),gep,ci);
1606 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1607 ci->eraseFromParent();
1615 /// This LibCallOptimization will simplify calls to the "fputs" library
1616 /// function. It looks for cases where the result of fputs is not used and the
1617 /// operation can be reduced to something simpler.
1618 /// @brief Simplify the puts library function.
1619 struct VISIBILITY_HIDDEN PutsOptimization : public LibCallOptimization {
1621 /// @brief Default Constructor
1622 PutsOptimization() : LibCallOptimization("fputs",
1623 "Number of 'fputs' calls simplified") {}
1625 /// @brief Make sure that the "fputs" function has the right prototype
1626 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1627 // Just make sure this has 2 arguments
1628 return F->arg_size() == 2;
1631 /// @brief Perform the fputs optimization.
1632 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1633 // If the result is used, none of these optimizations work
1634 if (!ci->use_empty())
1637 // All the optimizations depend on the length of the first argument and the
1638 // fact that it is a constant string array. Check that now
1640 if (!getConstantStringLength(ci->getOperand(1), len))
1645 // fputs("",F) -> noop
1649 // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
1650 const Type* FILEptr_type = ci->getOperand(2)->getType();
1651 LoadInst* loadi = new LoadInst(ci->getOperand(1),
1652 ci->getOperand(1)->getName()+".byte",ci);
1653 CastInst* casti = new SExtInst(loadi, Type::Int32Ty,
1654 loadi->getName()+".int", ci);
1655 new CallInst(SLC.get_fputc(FILEptr_type), casti,
1656 ci->getOperand(2), "", ci);
1661 // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
1662 const Type* FILEptr_type = ci->getOperand(2)->getType();
1663 std::vector<Value*> parms;
1664 parms.push_back(ci->getOperand(1));
1665 parms.push_back(ConstantInt::get(SLC.getIntPtrType(),len));
1666 parms.push_back(ConstantInt::get(SLC.getIntPtrType(),1));
1667 parms.push_back(ci->getOperand(2));
1668 new CallInst(SLC.get_fwrite(FILEptr_type), parms, "", ci);
1672 ci->eraseFromParent();
1673 return true; // success
1677 /// This LibCallOptimization will simplify calls to the "isdigit" library
1678 /// function. It simply does range checks the parameter explicitly.
1679 /// @brief Simplify the isdigit library function.
1680 struct VISIBILITY_HIDDEN isdigitOptimization : public LibCallOptimization {
1682 isdigitOptimization() : LibCallOptimization("isdigit",
1683 "Number of 'isdigit' calls simplified") {}
1685 /// @brief Make sure that the "isdigit" function has the right prototype
1686 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1687 // Just make sure this has 1 argument
1688 return (f->arg_size() == 1);
1691 /// @brief Perform the toascii optimization.
1692 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1693 if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
1694 // isdigit(c) -> 0 or 1, if 'c' is constant
1695 uint64_t val = CI->getZExtValue();
1696 if (val >= '0' && val <='9')
1697 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1699 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1700 ci->eraseFromParent();
1704 // isdigit(c) -> (unsigned)c - '0' <= 9
1705 CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
1706 Type::Int32Ty, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
1707 BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
1708 ConstantInt::get(Type::Int32Ty,0x30),
1709 ci->getOperand(1)->getName()+".sub",ci);
1710 ICmpInst* setcond_inst = new ICmpInst(ICmpInst::ICMP_ULE,sub_inst,
1711 ConstantInt::get(Type::Int32Ty,9),
1712 ci->getOperand(1)->getName()+".cmp",ci);
1713 CastInst* c2 = new ZExtInst(setcond_inst, Type::Int32Ty,
1714 ci->getOperand(1)->getName()+".isdigit", ci);
1715 ci->replaceAllUsesWith(c2);
1716 ci->eraseFromParent();
1721 struct VISIBILITY_HIDDEN isasciiOptimization : public LibCallOptimization {
1723 isasciiOptimization()
1724 : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
1726 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1727 return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() &&
1728 F->getReturnType()->isInteger();
1731 /// @brief Perform the isascii optimization.
1732 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1733 // isascii(c) -> (unsigned)c < 128
1734 Value *V = CI->getOperand(1);
1735 Value *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, V,
1736 ConstantInt::get(V->getType(), 128),
1737 V->getName()+".isascii", CI);
1738 if (Cmp->getType() != CI->getType())
1739 Cmp = new BitCastInst(Cmp, CI->getType(), Cmp->getName(), CI);
1740 CI->replaceAllUsesWith(Cmp);
1741 CI->eraseFromParent();
1747 /// This LibCallOptimization will simplify calls to the "toascii" library
1748 /// function. It simply does the corresponding and operation to restrict the
1749 /// range of values to the ASCII character set (0-127).
1750 /// @brief Simplify the toascii library function.
1751 struct VISIBILITY_HIDDEN ToAsciiOptimization : public LibCallOptimization {
1753 /// @brief Default Constructor
1754 ToAsciiOptimization() : LibCallOptimization("toascii",
1755 "Number of 'toascii' calls simplified") {}
1757 /// @brief Make sure that the "fputs" function has the right prototype
1758 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1759 // Just make sure this has 2 arguments
1760 return (f->arg_size() == 1);
1763 /// @brief Perform the toascii optimization.
1764 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1765 // toascii(c) -> (c & 0x7f)
1766 Value* chr = ci->getOperand(1);
1767 BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
1768 ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
1769 ci->replaceAllUsesWith(and_inst);
1770 ci->eraseFromParent();
1775 /// This LibCallOptimization will simplify calls to the "ffs" library
1776 /// calls which find the first set bit in an int, long, or long long. The
1777 /// optimization is to compute the result at compile time if the argument is
1779 /// @brief Simplify the ffs library function.
1780 struct VISIBILITY_HIDDEN FFSOptimization : public LibCallOptimization {
1782 /// @brief Subclass Constructor
1783 FFSOptimization(const char* funcName, const char* description)
1784 : LibCallOptimization(funcName, description) {}
1787 /// @brief Default Constructor
1788 FFSOptimization() : LibCallOptimization("ffs",
1789 "Number of 'ffs' calls simplified") {}
1791 /// @brief Make sure that the "ffs" function has the right prototype
1792 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1793 // Just make sure this has 2 arguments
1794 return F->arg_size() == 1 && F->getReturnType() == Type::Int32Ty;
1797 /// @brief Perform the ffs optimization.
1798 virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
1799 if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
1800 // ffs(cnst) -> bit#
1801 // ffsl(cnst) -> bit#
1802 // ffsll(cnst) -> bit#
1803 uint64_t val = CI->getZExtValue();
1807 while ((val & 1) == 0) {
1812 TheCall->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, result));
1813 TheCall->eraseFromParent();
1817 // ffs(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1818 // ffsl(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1819 // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1820 const Type *ArgType = TheCall->getOperand(1)->getType();
1821 const char *CTTZName;
1822 assert(ArgType->getTypeID() == Type::IntegerTyID &&
1823 "llvm.cttz argument is not an integer?");
1824 unsigned BitWidth = cast<IntegerType>(ArgType)->getBitWidth();
1826 CTTZName = "llvm.cttz.i8";
1827 else if (BitWidth == 16)
1828 CTTZName = "llvm.cttz.i16";
1829 else if (BitWidth == 32)
1830 CTTZName = "llvm.cttz.i32";
1832 assert(BitWidth == 64 && "Unknown bitwidth");
1833 CTTZName = "llvm.cttz.i64";
1836 Constant *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
1838 Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType,
1839 false/*ZExt*/, "tmp", TheCall);
1840 Value *V2 = new CallInst(F, V, "tmp", TheCall);
1841 V2 = CastInst::createIntegerCast(V2, Type::Int32Ty, false/*ZExt*/,
1843 V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::Int32Ty, 1),
1845 Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, V,
1846 Constant::getNullValue(V->getType()), "tmp",
1848 V2 = new SelectInst(Cond, ConstantInt::get(Type::Int32Ty, 0), V2,
1849 TheCall->getName(), TheCall);
1850 TheCall->replaceAllUsesWith(V2);
1851 TheCall->eraseFromParent();
1856 /// This LibCallOptimization will simplify calls to the "ffsl" library
1857 /// calls. It simply uses FFSOptimization for which the transformation is
1859 /// @brief Simplify the ffsl library function.
1860 struct VISIBILITY_HIDDEN FFSLOptimization : public FFSOptimization {
1862 /// @brief Default Constructor
1863 FFSLOptimization() : FFSOptimization("ffsl",
1864 "Number of 'ffsl' calls simplified") {}
1868 /// This LibCallOptimization will simplify calls to the "ffsll" library
1869 /// calls. It simply uses FFSOptimization for which the transformation is
1871 /// @brief Simplify the ffsl library function.
1872 struct VISIBILITY_HIDDEN FFSLLOptimization : public FFSOptimization {
1874 /// @brief Default Constructor
1875 FFSLLOptimization() : FFSOptimization("ffsll",
1876 "Number of 'ffsll' calls simplified") {}
1880 /// This optimizes unary functions that take and return doubles.
1881 struct UnaryDoubleFPOptimizer : public LibCallOptimization {
1882 UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
1883 : LibCallOptimization(Fn, Desc) {}
1885 // Make sure that this function has the right prototype
1886 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1887 return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
1888 F->getReturnType() == Type::DoubleTy;
1891 /// ShrinkFunctionToFloatVersion - If the input to this function is really a
1892 /// float, strength reduce this to a float version of the function,
1893 /// e.g. floor((double)FLT) -> (double)floorf(FLT). This can only be called
1894 /// when the target supports the destination function and where there can be
1895 /// no precision loss.
1896 static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
1897 Constant *(SimplifyLibCalls::*FP)()){
1898 if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
1899 if (Cast->getOperand(0)->getType() == Type::FloatTy) {
1900 Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
1902 New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
1903 CI->replaceAllUsesWith(New);
1904 CI->eraseFromParent();
1905 if (Cast->use_empty())
1906 Cast->eraseFromParent();
1914 struct VISIBILITY_HIDDEN FloorOptimization : public UnaryDoubleFPOptimizer {
1916 : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
1918 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1920 // If this is a float argument passed in, convert to floorf.
1921 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
1924 return false; // opt failed
1928 struct VISIBILITY_HIDDEN CeilOptimization : public UnaryDoubleFPOptimizer {
1930 : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
1932 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1934 // If this is a float argument passed in, convert to ceilf.
1935 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
1938 return false; // opt failed
1942 struct VISIBILITY_HIDDEN RoundOptimization : public UnaryDoubleFPOptimizer {
1944 : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
1946 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1948 // If this is a float argument passed in, convert to roundf.
1949 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
1952 return false; // opt failed
1956 struct VISIBILITY_HIDDEN RintOptimization : public UnaryDoubleFPOptimizer {
1958 : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
1960 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1962 // If this is a float argument passed in, convert to rintf.
1963 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
1966 return false; // opt failed
1970 struct VISIBILITY_HIDDEN NearByIntOptimization : public UnaryDoubleFPOptimizer {
1971 NearByIntOptimization()
1972 : UnaryDoubleFPOptimizer("nearbyint",
1973 "Number of 'nearbyint' calls simplified") {}
1975 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1976 #ifdef HAVE_NEARBYINTF
1977 // If this is a float argument passed in, convert to nearbyintf.
1978 if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
1981 return false; // opt failed
1983 } NearByIntOptimizer;
1985 /// A function to compute the length of a null-terminated constant array of
1986 /// integers. This function can't rely on the size of the constant array
1987 /// because there could be a null terminator in the middle of the array.
1988 /// We also have to bail out if we find a non-integer constant initializer
1989 /// of one of the elements or if there is no null-terminator. The logic
1990 /// below checks each of these conditions and will return true only if all
1991 /// conditions are met. In that case, the \p len parameter is set to the length
1992 /// of the null-terminated string. If false is returned, the conditions were
1993 /// not met and len is set to 0.
1994 /// @brief Get the length of a constant string (null-terminated array).
1995 static bool getConstantStringLength(Value *V, uint64_t &len, ConstantArray **CA)
1997 assert(V != 0 && "Invalid args to getConstantStringLength");
1998 len = 0; // make sure we initialize this
2000 // If the value is not a GEP instruction nor a constant expression with a
2001 // GEP instruction, then return false because ConstantArray can't occur
2003 if (GetElementPtrInst* GEPI = dyn_cast<GetElementPtrInst>(V))
2005 else if (ConstantExpr* CE = dyn_cast<ConstantExpr>(V))
2006 if (CE->getOpcode() == Instruction::GetElementPtr)
2013 // Make sure the GEP has exactly three arguments.
2014 if (GEP->getNumOperands() != 3)
2017 // Check to make sure that the first operand of the GEP is an integer and
2018 // has value 0 so that we are sure we're indexing into the initializer.
2019 if (ConstantInt* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
2020 if (!op1->isNullValue())
2025 // Ensure that the second operand is a ConstantInt. If it isn't then this
2026 // GEP is wonky and we're not really sure what were referencing into and
2027 // better of not optimizing it. While we're at it, get the second index
2028 // value. We'll need this later for indexing the ConstantArray.
2029 uint64_t start_idx = 0;
2030 if (ConstantInt* CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
2031 start_idx = CI->getZExtValue();
2035 // The GEP instruction, constant or instruction, must reference a global
2036 // variable that is a constant and is initialized. The referenced constant
2037 // initializer is the array that we'll use for optimization.
2038 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
2039 if (!GV || !GV->isConstant() || !GV->hasInitializer())
2042 // Get the initializer.
2043 Constant* INTLZR = GV->getInitializer();
2045 // Handle the ConstantAggregateZero case
2046 if (isa<ConstantAggregateZero>(INTLZR)) {
2047 // This is a degenerate case. The initializer is constant zero so the
2048 // length of the string must be zero.
2053 // Must be a Constant Array
2054 ConstantArray* A = dyn_cast<ConstantArray>(INTLZR);
2058 // Get the number of elements in the array
2059 uint64_t max_elems = A->getType()->getNumElements();
2061 // Traverse the constant array from start_idx (derived above) which is
2062 // the place the GEP refers to in the array.
2063 for (len = start_idx; len < max_elems; len++) {
2064 if (ConstantInt *CI = dyn_cast<ConstantInt>(A->getOperand(len))) {
2065 // Check for the null terminator
2066 if (CI->isNullValue())
2067 break; // we found end of string
2069 return false; // This array isn't suitable, non-int initializer
2072 if (len >= max_elems)
2073 return false; // This array isn't null terminated
2075 // Subtract out the initial value from the length
2079 return true; // success!
2082 /// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
2083 /// inserting the cast before IP, and return the cast.
2084 /// @brief Cast a value to a "C" string.
2085 static Value *CastToCStr(Value *V, Instruction &IP) {
2086 assert(isa<PointerType>(V->getType()) &&
2087 "Can't cast non-pointer type to C string type");
2088 const Type *SBPTy = PointerType::get(Type::Int8Ty);
2089 if (V->getType() != SBPTy)
2090 return new BitCastInst(V, SBPTy, V->getName(), &IP);
2095 // Additional cases that we need to add to this file:
2098 // * cbrt(expN(X)) -> expN(x/3)
2099 // * cbrt(sqrt(x)) -> pow(x,1/6)
2100 // * cbrt(sqrt(x)) -> pow(x,1/9)
2103 // * cos(-x) -> cos(x)
2106 // * exp(log(x)) -> x
2109 // * log(exp(x)) -> x
2110 // * log(x**y) -> y*log(x)
2111 // * log(exp(y)) -> y*log(e)
2112 // * log(exp2(y)) -> y*log(2)
2113 // * log(exp10(y)) -> y*log(10)
2114 // * log(sqrt(x)) -> 0.5*log(x)
2115 // * log(pow(x,y)) -> y*log(x)
2117 // lround, lroundf, lroundl:
2118 // * lround(cnst) -> cnst'
2121 // * memcmp(x,y,l) -> cnst
2122 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
2125 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
2126 // (if s is a global constant array)
2129 // * pow(exp(x),y) -> exp(x*y)
2130 // * pow(sqrt(x),y) -> pow(x,y*0.5)
2131 // * pow(pow(x,y),z)-> pow(x,y*z)
2134 // * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
2136 // round, roundf, roundl:
2137 // * round(cnst) -> cnst'
2140 // * signbit(cnst) -> cnst'
2141 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2143 // sqrt, sqrtf, sqrtl:
2144 // * sqrt(expN(x)) -> expN(x*0.5)
2145 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2146 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2149 // * stpcpy(str, "literal") ->
2150 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
2152 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
2153 // (if c is a constant integer and s is a constant string)
2154 // * strrchr(s1,0) -> strchr(s1,0)
2157 // * strncat(x,y,0) -> x
2158 // * strncat(x,y,0) -> x (if strlen(y) = 0)
2159 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
2162 // * strncpy(d,s,0) -> d
2163 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
2164 // (if s and l are constants)
2167 // * strpbrk(s,a) -> offset_in_for(s,a)
2168 // (if s and a are both constant strings)
2169 // * strpbrk(s,"") -> 0
2170 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
2173 // * strspn(s,a) -> const_int (if both args are constant)
2174 // * strspn("",a) -> 0
2175 // * strspn(s,"") -> 0
2176 // * strcspn(s,a) -> const_int (if both args are constant)
2177 // * strcspn("",a) -> 0
2178 // * strcspn(s,"") -> strlen(a)
2181 // * strstr(x,x) -> x
2182 // * strstr(s1,s2) -> offset_of_s2_in(s1)
2183 // (if s1 and s2 are constant strings)
2186 // * tan(atan(x)) -> x
2188 // trunc, truncf, truncl:
2189 // * trunc(cnst) -> cnst'