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 GetConstantStringInfo(Value *V, ConstantArray *&Array,
388 uint64_t &Length, uint64_t &StartIdx);
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
485 uint64_t len, StartIdx;
487 if (!GetConstantStringInfo(src, Arr, len, StartIdx))
490 // Handle the simple, do-nothing case
492 ci->replaceAllUsesWith(dest);
493 ci->eraseFromParent();
497 // Increment the length because we actually want to memcpy the null
498 // terminator as well.
501 // We need to find the end of the destination string. That's where the
502 // memory is to be moved to. We just generate a call to strlen (further
503 // optimized in another pass). Note that the SLC.get_strlen() call
504 // caches the Function* for us.
505 CallInst* strlen_inst =
506 new CallInst(SLC.get_strlen(), dest, dest->getName()+".len",ci);
508 // Now that we have the destination's length, we must index into the
509 // destination's pointer to get the actual memcpy destination (end of
510 // the string .. we're concatenating).
511 GetElementPtrInst* gep =
512 new GetElementPtrInst(dest, strlen_inst, dest->getName()+".indexed", ci);
514 // We have enough information to now generate the memcpy call to
515 // do the concatenation for us.
517 vals[0] = gep; // destination
518 vals[1] = ci->getOperand(2); // source
519 vals[2] = ConstantInt::get(SLC.getIntPtrType(),len); // length
520 vals[3] = ConstantInt::get(Type::Int32Ty,1); // alignment
521 new CallInst(SLC.get_memcpy(), vals, 4, "", ci);
523 // Finally, substitute the first operand of the strcat call for the
524 // strcat call itself since strcat returns its first operand; and,
525 // kill the strcat CallInst.
526 ci->replaceAllUsesWith(dest);
527 ci->eraseFromParent();
532 /// This LibCallOptimization will simplify a call to the strchr library
533 /// function. It optimizes out cases where the arguments are both constant
534 /// and the result can be determined statically.
535 /// @brief Simplify the strcmp library function.
536 struct VISIBILITY_HIDDEN StrChrOptimization : public LibCallOptimization {
538 StrChrOptimization() : LibCallOptimization("strchr",
539 "Number of 'strchr' calls simplified") {}
541 /// @brief Make sure that the "strchr" function has the right prototype
542 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
543 if (f->getReturnType() == PointerType::get(Type::Int8Ty) &&
549 /// @brief Perform the strchr optimizations
550 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
551 // If there aren't three operands, bail
552 if (ci->getNumOperands() != 3)
555 // Check that the first argument to strchr is a constant array of sbyte.
556 // If it is, get the length and data, otherwise return false.
557 uint64_t len, StartIdx;
558 ConstantArray* CA = 0;
559 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
562 // Check that the second argument to strchr is a constant int. If it isn't
563 // a constant integer, we can try an alternate optimization
564 ConstantInt* CSI = dyn_cast<ConstantInt>(ci->getOperand(2));
566 // The second operand is not constant just lower this to
567 // memchr since we know the length of the string since it is constant.
568 Constant *f = SLC.get_memchr();
572 ConstantInt::get(SLC.getIntPtrType(), len)
574 ci->replaceAllUsesWith(new CallInst(f, args, 3, ci->getName(), ci));
575 ci->eraseFromParent();
579 // Get the character we're looking for
580 int64_t chr = CSI->getSExtValue();
582 // Compute the offset
584 bool char_found = false;
585 for (uint64_t i = 0; i < len; ++i) {
586 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
587 // Check for the null terminator
589 break; // we found end of string
590 else if (CI->getSExtValue() == chr) {
598 // strchr(s,c) -> offset_of_in(c,s)
599 // (if c is a constant integer and s is a constant string)
601 Value* Idx = ConstantInt::get(Type::Int64Ty,offset);
602 GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1), Idx,
603 ci->getOperand(1)->getName()+".strchr",ci);
604 ci->replaceAllUsesWith(GEP);
606 ci->replaceAllUsesWith(
607 ConstantPointerNull::get(PointerType::get(Type::Int8Ty)));
609 ci->eraseFromParent();
614 /// This LibCallOptimization will simplify a call to the strcmp library
615 /// function. It optimizes out cases where one or both arguments are constant
616 /// and the result can be determined statically.
617 /// @brief Simplify the strcmp library function.
618 struct VISIBILITY_HIDDEN StrCmpOptimization : public LibCallOptimization {
620 StrCmpOptimization() : LibCallOptimization("strcmp",
621 "Number of 'strcmp' calls simplified") {}
623 /// @brief Make sure that the "strcmp" function has the right prototype
624 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
625 return F->getReturnType() == Type::Int32Ty && F->arg_size() == 2;
628 /// @brief Perform the strcmp optimization
629 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
630 // First, check to see if src and destination are the same. If they are,
631 // then the optimization is to replace the CallInst with a constant 0
632 // because the call is a no-op.
633 Value* s1 = ci->getOperand(1);
634 Value* s2 = ci->getOperand(2);
637 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
638 ci->eraseFromParent();
642 bool isstr_1 = false;
643 uint64_t len_1 = 0, StartIdx;
645 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
648 // strcmp("",x) -> *x
650 new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
652 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
653 ci->getName()+".int", ci);
654 ci->replaceAllUsesWith(cast);
655 ci->eraseFromParent();
660 bool isstr_2 = false;
663 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
666 // strcmp(x,"") -> *x
668 new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
670 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
671 ci->getName()+".int", ci);
672 ci->replaceAllUsesWith(cast);
673 ci->eraseFromParent();
678 if (isstr_1 && isstr_2) {
679 // strcmp(x,y) -> cnst (if both x and y are constant strings)
680 std::string str1 = A1->getAsString();
681 std::string str2 = A2->getAsString();
682 int result = strcmp(str1.c_str(), str2.c_str());
683 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
684 ci->eraseFromParent();
691 /// This LibCallOptimization will simplify a call to the strncmp library
692 /// function. It optimizes out cases where one or both arguments are constant
693 /// and the result can be determined statically.
694 /// @brief Simplify the strncmp library function.
695 struct VISIBILITY_HIDDEN StrNCmpOptimization : public LibCallOptimization {
697 StrNCmpOptimization() : LibCallOptimization("strncmp",
698 "Number of 'strncmp' calls simplified") {}
700 /// @brief Make sure that the "strncmp" function has the right prototype
701 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
702 if (f->getReturnType() == Type::Int32Ty && f->arg_size() == 3)
707 /// @brief Perform the strncpy optimization
708 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
709 // First, check to see if src and destination are the same. If they are,
710 // then the optimization is to replace the CallInst with a constant 0
711 // because the call is a no-op.
712 Value* s1 = ci->getOperand(1);
713 Value* s2 = ci->getOperand(2);
715 // strncmp(x,x,l) -> 0
716 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
717 ci->eraseFromParent();
721 // Check the length argument, if it is Constant zero then the strings are
723 uint64_t len_arg = 0;
724 bool len_arg_is_const = false;
725 if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
726 len_arg_is_const = true;
727 len_arg = len_CI->getZExtValue();
729 // strncmp(x,y,0) -> 0
730 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
731 ci->eraseFromParent();
736 bool isstr_1 = false;
737 uint64_t len_1 = 0, StartIdx;
739 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
742 // strncmp("",x) -> *x
743 LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
745 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
746 ci->getName()+".int", ci);
747 ci->replaceAllUsesWith(cast);
748 ci->eraseFromParent();
753 bool isstr_2 = false;
756 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
759 // strncmp(x,"") -> *x
760 LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
762 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
763 ci->getName()+".int", ci);
764 ci->replaceAllUsesWith(cast);
765 ci->eraseFromParent();
770 if (isstr_1 && isstr_2 && len_arg_is_const) {
771 // strncmp(x,y,const) -> constant
772 std::string str1 = A1->getAsString();
773 std::string str2 = A2->getAsString();
774 int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
775 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
776 ci->eraseFromParent();
783 /// This LibCallOptimization will simplify a call to the strcpy library
784 /// function. Two optimizations are possible:
785 /// (1) If src and dest are the same and not volatile, just return dest
786 /// (2) If the src is a constant then we can convert to llvm.memmove
787 /// @brief Simplify the strcpy library function.
788 struct VISIBILITY_HIDDEN StrCpyOptimization : public LibCallOptimization {
790 StrCpyOptimization() : LibCallOptimization("strcpy",
791 "Number of 'strcpy' calls simplified") {}
793 /// @brief Make sure that the "strcpy" function has the right prototype
794 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
795 if (f->getReturnType() == PointerType::get(Type::Int8Ty))
796 if (f->arg_size() == 2) {
797 Function::const_arg_iterator AI = f->arg_begin();
798 if (AI++->getType() == PointerType::get(Type::Int8Ty))
799 if (AI->getType() == PointerType::get(Type::Int8Ty)) {
800 // Indicate this is a suitable call type.
807 /// @brief Perform the strcpy optimization
808 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
809 // First, check to see if src and destination are the same. If they are,
810 // then the optimization is to replace the CallInst with the destination
811 // because the call is a no-op. Note that this corresponds to the
812 // degenerate strcpy(X,X) case which should have "undefined" results
813 // according to the C specification. However, it occurs sometimes and
814 // we optimize it as a no-op.
815 Value* dest = ci->getOperand(1);
816 Value* src = ci->getOperand(2);
818 ci->replaceAllUsesWith(dest);
819 ci->eraseFromParent();
823 // Get the length of the constant string referenced by the second operand,
824 // the "src" parameter. Fail the optimization if we can't get the length
825 // (note that GetConstantStringInfo does lots of checks to make sure this
827 uint64_t len, StartIdx;
829 if (!GetConstantStringInfo(ci->getOperand(2), A, len, StartIdx))
832 // If the constant string's length is zero we can optimize this by just
833 // doing a store of 0 at the first byte of the destination
835 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
836 ci->replaceAllUsesWith(dest);
837 ci->eraseFromParent();
841 // Increment the length because we actually want to memcpy the null
842 // terminator as well.
845 // We have enough information to now generate the memcpy call to
846 // do the concatenation for us.
849 ConstantInt::get(SLC.getIntPtrType(),len), // length
850 ConstantInt::get(Type::Int32Ty, 1) // alignment
852 new CallInst(SLC.get_memcpy(), vals, 4, "", ci);
854 // Finally, substitute the first operand of the strcat call for the
855 // strcat call itself since strcat returns its first operand; and,
856 // kill the strcat CallInst.
857 ci->replaceAllUsesWith(dest);
858 ci->eraseFromParent();
863 /// This LibCallOptimization will simplify a call to the strlen library
864 /// function by replacing it with a constant value if the string provided to
865 /// it is a constant array.
866 /// @brief Simplify the strlen library function.
867 struct VISIBILITY_HIDDEN StrLenOptimization : public LibCallOptimization {
868 StrLenOptimization() : LibCallOptimization("strlen",
869 "Number of 'strlen' calls simplified") {}
871 /// @brief Make sure that the "strlen" function has the right prototype
872 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
874 if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
875 if (f->arg_size() == 1)
876 if (Function::const_arg_iterator AI = f->arg_begin())
877 if (AI->getType() == PointerType::get(Type::Int8Ty))
882 /// @brief Perform the strlen optimization
883 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
885 // Make sure we're dealing with an sbyte* here.
886 Value* str = ci->getOperand(1);
887 if (str->getType() != PointerType::get(Type::Int8Ty))
890 // Does the call to strlen have exactly one use?
892 // Is that single use a icmp operator?
893 if (ICmpInst* bop = dyn_cast<ICmpInst>(ci->use_back()))
894 // Is it compared against a constant integer?
895 if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
897 // Get the value the strlen result is compared to
898 uint64_t val = CI->getZExtValue();
900 // If its compared against length 0 with == or !=
902 (bop->getPredicate() == ICmpInst::ICMP_EQ ||
903 bop->getPredicate() == ICmpInst::ICMP_NE))
905 // strlen(x) != 0 -> *x != 0
906 // strlen(x) == 0 -> *x == 0
907 LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
908 ICmpInst* rbop = new ICmpInst(bop->getPredicate(), load,
909 ConstantInt::get(Type::Int8Ty,0),
910 bop->getName()+".strlen", ci);
911 bop->replaceAllUsesWith(rbop);
912 bop->eraseFromParent();
913 ci->eraseFromParent();
918 // Get the length of the constant string operand
919 uint64_t len = 0, StartIdx;
921 if (!GetConstantStringInfo(ci->getOperand(1), A, len, StartIdx))
924 // strlen("xyz") -> 3 (for example)
925 const Type *Ty = SLC.getTargetData()->getIntPtrType();
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 (ICmpInst *IC = dyn_cast<ICmpInst>(User)) {
940 if ((IC->getPredicate() == ICmpInst::ICMP_NE ||
941 IC->getPredicate() == ICmpInst::ICMP_EQ) &&
942 isa<Constant>(IC->getOperand(1)) &&
943 cast<Constant>(IC->getOperand(1))->isNullValue())
945 } else if (CastInst *CI = dyn_cast<CastInst>(User))
946 if (CI->getType() == Type::Int1Ty)
948 // Unknown instruction.
954 /// This memcmpOptimization will simplify a call to the memcmp library
956 struct VISIBILITY_HIDDEN memcmpOptimization : public LibCallOptimization {
957 /// @brief Default Constructor
959 : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
961 /// @brief Make sure that the "memcmp" function has the right prototype
962 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
963 Function::const_arg_iterator AI = F->arg_begin();
964 if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
965 if (!isa<PointerType>((++AI)->getType())) return false;
966 if (!(++AI)->getType()->isInteger()) return false;
967 if (!F->getReturnType()->isInteger()) return false;
971 /// Because of alignment and instruction information that we don't have, we
972 /// leave the bulk of this to the code generators.
974 /// Note that we could do much more if we could force alignment on otherwise
975 /// small aligned allocas, or if we could indicate that loads have a small
977 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
978 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
980 // If the two operands are the same, return zero.
982 // memcmp(s,s,x) -> 0
983 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
984 CI->eraseFromParent();
988 // Make sure we have a constant length.
989 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
990 if (!LenC) return false;
991 uint64_t Len = LenC->getZExtValue();
993 // If the length is zero, this returns 0.
996 // memcmp(s1,s2,0) -> 0
997 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
998 CI->eraseFromParent();
1001 // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
1002 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1003 CastInst *Op1Cast = CastInst::create(
1004 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1005 CastInst *Op2Cast = CastInst::create(
1006 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1007 Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
1008 Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
1009 Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
1010 if (RV->getType() != CI->getType())
1011 RV = CastInst::createIntegerCast(RV, CI->getType(), false,
1013 CI->replaceAllUsesWith(RV);
1014 CI->eraseFromParent();
1018 if (IsOnlyUsedInEqualsZeroComparison(CI)) {
1019 // TODO: IF both are aligned, use a short load/compare.
1021 // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
1022 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1023 CastInst *Op1Cast = CastInst::create(
1024 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1025 CastInst *Op2Cast = CastInst::create(
1026 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1027 Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
1028 Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
1029 Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
1030 CI->getName()+".d1", CI);
1031 Constant *One = ConstantInt::get(Type::Int32Ty, 1);
1032 Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
1033 Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
1034 Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
1035 Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
1036 Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
1037 CI->getName()+".d1", CI);
1038 Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
1039 if (Or->getType() != CI->getType())
1040 Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/,
1042 CI->replaceAllUsesWith(Or);
1043 CI->eraseFromParent();
1056 /// This LibCallOptimization will simplify a call to the memcpy library
1057 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1058 /// bytes depending on the length of the string and the alignment. Additional
1059 /// optimizations are possible in code generation (sequence of immediate store)
1060 /// @brief Simplify the memcpy library function.
1061 struct VISIBILITY_HIDDEN LLVMMemCpyMoveOptzn : public LibCallOptimization {
1062 LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
1063 : LibCallOptimization(fname, desc) {}
1065 /// @brief Make sure that the "memcpy" function has the right prototype
1066 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
1067 // Just make sure this has 4 arguments per LLVM spec.
1068 return (f->arg_size() == 4);
1071 /// Because of alignment and instruction information that we don't have, we
1072 /// leave the bulk of this to the code generators. The optimization here just
1073 /// deals with a few degenerate cases where the length of the string and the
1074 /// alignment match the sizes of our intrinsic types so we can do a load and
1075 /// store instead of the memcpy call.
1076 /// @brief Perform the memcpy optimization.
1077 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
1078 // Make sure we have constant int values to work with
1079 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1082 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1086 // If the length is larger than the alignment, we can't optimize
1087 uint64_t len = LEN->getZExtValue();
1088 uint64_t alignment = ALIGN->getZExtValue();
1090 alignment = 1; // Alignment 0 is identity for alignment 1
1091 if (len > alignment)
1094 // Get the type we will cast to, based on size of the string
1095 Value* dest = ci->getOperand(1);
1096 Value* src = ci->getOperand(2);
1097 const Type* castType = 0;
1101 // memcpy(d,s,0,a) -> noop
1102 ci->eraseFromParent();
1104 case 1: castType = Type::Int8Ty; break;
1105 case 2: castType = Type::Int16Ty; break;
1106 case 4: castType = Type::Int32Ty; break;
1107 case 8: castType = Type::Int64Ty; break;
1112 // Cast source and dest to the right sized primitive and then load/store
1113 CastInst* SrcCast = CastInst::create(Instruction::BitCast,
1114 src, PointerType::get(castType), src->getName()+".cast", ci);
1115 CastInst* DestCast = CastInst::create(Instruction::BitCast,
1116 dest, PointerType::get(castType),dest->getName()+".cast", ci);
1117 LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
1118 new StoreInst(LI, DestCast, ci);
1119 ci->eraseFromParent();
1124 /// This LibCallOptimization will simplify a call to the memcpy/memmove library
1126 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
1127 "Number of 'llvm.memcpy' calls simplified");
1128 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
1129 "Number of 'llvm.memcpy' calls simplified");
1130 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
1131 "Number of 'llvm.memmove' calls simplified");
1132 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
1133 "Number of 'llvm.memmove' calls simplified");
1135 /// This LibCallOptimization will simplify a call to the memset library
1136 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1137 /// bytes depending on the length argument.
1138 struct VISIBILITY_HIDDEN LLVMMemSetOptimization : public LibCallOptimization {
1139 /// @brief Default Constructor
1140 LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
1141 "Number of 'llvm.memset' calls simplified") {}
1143 /// @brief Make sure that the "memset" function has the right prototype
1144 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
1145 // Just make sure this has 3 arguments per LLVM spec.
1146 return F->arg_size() == 4;
1149 /// Because of alignment and instruction information that we don't have, we
1150 /// leave the bulk of this to the code generators. The optimization here just
1151 /// deals with a few degenerate cases where the length parameter is constant
1152 /// and the alignment matches the sizes of our intrinsic types so we can do
1153 /// store instead of the memcpy call. Other calls are transformed into the
1154 /// llvm.memset intrinsic.
1155 /// @brief Perform the memset optimization.
1156 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
1157 // Make sure we have constant int values to work with
1158 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1161 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1165 // Extract the length and alignment
1166 uint64_t len = LEN->getZExtValue();
1167 uint64_t alignment = ALIGN->getZExtValue();
1169 // Alignment 0 is identity for alignment 1
1173 // If the length is zero, this is a no-op
1175 // memset(d,c,0,a) -> noop
1176 ci->eraseFromParent();
1180 // If the length is larger than the alignment, we can't optimize
1181 if (len > alignment)
1184 // Make sure we have a constant ubyte to work with so we can extract
1185 // the value to be filled.
1186 ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
1189 if (FILL->getType() != Type::Int8Ty)
1192 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
1194 // Extract the fill character
1195 uint64_t fill_char = FILL->getZExtValue();
1196 uint64_t fill_value = fill_char;
1198 // Get the type we will cast to, based on size of memory area to fill, and
1199 // and the value we will store there.
1200 Value* dest = ci->getOperand(1);
1201 const Type* castType = 0;
1204 castType = Type::Int8Ty;
1207 castType = Type::Int16Ty;
1208 fill_value |= fill_char << 8;
1211 castType = Type::Int32Ty;
1212 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1215 castType = Type::Int64Ty;
1216 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1217 fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
1218 fill_value |= fill_char << 56;
1224 // Cast dest to the right sized primitive and then load/store
1225 CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType),
1226 dest->getName()+".cast", ci);
1227 new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
1228 ci->eraseFromParent();
1233 LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
1234 LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
1237 /// This LibCallOptimization will simplify calls to the "pow" library
1238 /// function. It looks for cases where the result of pow is well known and
1239 /// substitutes the appropriate value.
1240 /// @brief Simplify the pow library function.
1241 struct VISIBILITY_HIDDEN PowOptimization : public LibCallOptimization {
1243 /// @brief Default Constructor
1244 PowOptimization() : LibCallOptimization("pow",
1245 "Number of 'pow' calls simplified") {}
1247 /// @brief Make sure that the "pow" function has the right prototype
1248 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1249 // Just make sure this has 2 arguments
1250 return (f->arg_size() == 2);
1253 /// @brief Perform the pow optimization.
1254 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1255 const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
1256 Value* base = ci->getOperand(1);
1257 Value* expn = ci->getOperand(2);
1258 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
1259 double Op1V = Op1->getValue();
1261 // pow(1.0,x) -> 1.0
1262 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1263 ci->eraseFromParent();
1266 } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
1267 double Op2V = Op2->getValue();
1269 // pow(x,0.0) -> 1.0
1270 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1271 ci->eraseFromParent();
1273 } else if (Op2V == 0.5) {
1274 // pow(x,0.5) -> sqrt(x)
1275 CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
1276 ci->getName()+".pow",ci);
1277 ci->replaceAllUsesWith(sqrt_inst);
1278 ci->eraseFromParent();
1280 } else if (Op2V == 1.0) {
1282 ci->replaceAllUsesWith(base);
1283 ci->eraseFromParent();
1285 } else if (Op2V == -1.0) {
1286 // pow(x,-1.0) -> 1.0/x
1287 BinaryOperator* div_inst= BinaryOperator::createFDiv(
1288 ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
1289 ci->replaceAllUsesWith(div_inst);
1290 ci->eraseFromParent();
1294 return false; // opt failed
1298 /// This LibCallOptimization will simplify calls to the "printf" library
1299 /// function. It looks for cases where the result of printf is not used and the
1300 /// operation can be reduced to something simpler.
1301 /// @brief Simplify the printf library function.
1302 struct VISIBILITY_HIDDEN PrintfOptimization : public LibCallOptimization {
1304 /// @brief Default Constructor
1305 PrintfOptimization() : LibCallOptimization("printf",
1306 "Number of 'printf' calls simplified") {}
1308 /// @brief Make sure that the "printf" function has the right prototype
1309 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1310 // Just make sure this has at least 1 arguments
1311 return (f->arg_size() >= 1);
1314 /// @brief Perform the printf optimization.
1315 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1316 // If the call has more than 2 operands, we can't optimize it
1317 if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
1320 // If the result of the printf call is used, none of these optimizations
1322 if (!ci->use_empty())
1325 // All the optimizations depend on the length of the first argument and the
1326 // fact that it is a constant string array. Check that now
1327 uint64_t len, StartIdx;
1328 ConstantArray* CA = 0;
1329 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1332 if (len != 2 && len != 3)
1335 // The first character has to be a %
1336 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1337 if (CI->getZExtValue() != '%')
1340 // Get the second character and switch on its value
1341 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1342 switch (CI->getZExtValue()) {
1346 dyn_cast<ConstantInt>(CA->getOperand(2))->getZExtValue() != '\n')
1349 // printf("%s\n",str) -> puts(str)
1350 std::vector<Value*> args;
1351 new CallInst(SLC.get_puts(), CastToCStr(ci->getOperand(2), *ci),
1353 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1358 // printf("%c",c) -> putchar(c)
1362 CastInst *Char = CastInst::createSExtOrBitCast(
1363 ci->getOperand(2), Type::Int32Ty, CI->getName()+".int", ci);
1364 new CallInst(SLC.get_putchar(), Char, "", ci);
1365 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, 1));
1371 ci->eraseFromParent();
1376 /// This LibCallOptimization will simplify calls to the "fprintf" library
1377 /// function. It looks for cases where the result of fprintf is not used and the
1378 /// operation can be reduced to something simpler.
1379 /// @brief Simplify the fprintf library function.
1380 struct VISIBILITY_HIDDEN FPrintFOptimization : public LibCallOptimization {
1382 /// @brief Default Constructor
1383 FPrintFOptimization() : LibCallOptimization("fprintf",
1384 "Number of 'fprintf' calls simplified") {}
1386 /// @brief Make sure that the "fprintf" function has the right prototype
1387 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1388 // Just make sure this has at least 2 arguments
1389 return (f->arg_size() >= 2);
1392 /// @brief Perform the fprintf optimization.
1393 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1394 // If the call has more than 3 operands, we can't optimize it
1395 if (ci->getNumOperands() > 4 || ci->getNumOperands() <= 2)
1398 // If the result of the fprintf call is used, none of these optimizations
1400 if (!ci->use_empty())
1403 // All the optimizations depend on the length of the second argument and the
1404 // fact that it is a constant string array. Check that now
1405 uint64_t len, StartIdx;
1406 ConstantArray* CA = 0;
1407 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1410 if (ci->getNumOperands() == 3) {
1411 // Make sure there's no % in the constant array
1412 for (unsigned i = 0; i < len; ++i) {
1413 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1414 // Check for the null terminator
1415 if (CI->getZExtValue() == '%')
1416 return false; // we found end of string
1422 // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
1423 const Type* FILEptr_type = ci->getOperand(1)->getType();
1425 // Make sure that the fprintf() and fwrite() functions both take the
1426 // same type of char pointer.
1427 if (ci->getOperand(2)->getType() != PointerType::get(Type::Int8Ty))
1432 ConstantInt::get(SLC.getIntPtrType(),len),
1433 ConstantInt::get(SLC.getIntPtrType(),1),
1436 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4, ci->getName(), ci);
1437 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1438 ci->eraseFromParent();
1442 // The remaining optimizations require the format string to be length 2
1447 // The first character has to be a %
1448 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1449 if (CI->getZExtValue() != '%')
1452 // Get the second character and switch on its value
1453 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1454 switch (CI->getZExtValue()) {
1457 uint64_t len, StartIdx;
1458 ConstantArray* CA = 0;
1459 if (GetConstantStringInfo(ci->getOperand(3), CA, len, StartIdx)) {
1460 // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
1461 const Type* FILEptr_type = ci->getOperand(1)->getType();
1463 CastToCStr(ci->getOperand(3), *ci),
1464 ConstantInt::get(SLC.getIntPtrType(), len),
1465 ConstantInt::get(SLC.getIntPtrType(), 1),
1468 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4,ci->getName(), ci);
1469 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1471 // fprintf(file,"%s",str) -> fputs(str,file)
1472 const Type* FILEptr_type = ci->getOperand(1)->getType();
1473 new CallInst(SLC.get_fputs(FILEptr_type),
1474 CastToCStr(ci->getOperand(3), *ci),
1475 ci->getOperand(1), ci->getName(),ci);
1476 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1482 // fprintf(file,"%c",c) -> fputc(c,file)
1483 const Type* FILEptr_type = ci->getOperand(1)->getType();
1484 CastInst* cast = CastInst::createSExtOrBitCast(
1485 ci->getOperand(3), Type::Int32Ty, CI->getName()+".int", ci);
1486 new CallInst(SLC.get_fputc(FILEptr_type), cast,ci->getOperand(1),"",ci);
1487 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1493 ci->eraseFromParent();
1498 /// This LibCallOptimization will simplify calls to the "sprintf" library
1499 /// function. It looks for cases where the result of sprintf is not used and the
1500 /// operation can be reduced to something simpler.
1501 /// @brief Simplify the sprintf library function.
1502 struct VISIBILITY_HIDDEN SPrintFOptimization : public LibCallOptimization {
1504 /// @brief Default Constructor
1505 SPrintFOptimization() : LibCallOptimization("sprintf",
1506 "Number of 'sprintf' calls simplified") {}
1508 /// @brief Make sure that the "fprintf" function has the right prototype
1509 virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
1510 // Just make sure this has at least 2 arguments
1511 return (f->getReturnType() == Type::Int32Ty && f->arg_size() >= 2);
1514 /// @brief Perform the sprintf optimization.
1515 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1516 // If the call has more than 3 operands, we can't optimize it
1517 if (ci->getNumOperands() > 4 || ci->getNumOperands() < 3)
1520 // All the optimizations depend on the length of the second argument and the
1521 // fact that it is a constant string array. Check that now
1522 uint64_t len, StartIdx;
1523 ConstantArray* CA = 0;
1524 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1527 if (ci->getNumOperands() == 3) {
1529 // If the length is 0, we just need to store a null byte
1530 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
1531 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1532 ci->eraseFromParent();
1536 // Make sure there's no % in the constant array
1537 for (unsigned i = 0; i < len; ++i) {
1538 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1539 // Check for the null terminator
1540 if (CI->getZExtValue() == '%')
1541 return false; // we found a %, can't optimize
1543 return false; // initializer is not constant int, can't optimize
1547 // Increment length because we want to copy the null byte too
1550 // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
1554 ConstantInt::get(SLC.getIntPtrType(),len),
1555 ConstantInt::get(Type::Int32Ty, 1)
1557 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1558 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1559 ci->eraseFromParent();
1563 // The remaining optimizations require the format string to be length 2
1568 // The first character has to be a %
1569 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1570 if (CI->getZExtValue() != '%')
1573 // Get the second character and switch on its value
1574 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1575 switch (CI->getZExtValue()) {
1577 // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1578 Value *Len = new CallInst(SLC.get_strlen(),
1579 CastToCStr(ci->getOperand(3), *ci),
1580 ci->getOperand(3)->getName()+".len", ci);
1581 Value *Len1 = BinaryOperator::createAdd(Len,
1582 ConstantInt::get(Len->getType(), 1),
1583 Len->getName()+"1", ci);
1584 if (Len1->getType() != SLC.getIntPtrType())
1585 Len1 = CastInst::createIntegerCast(Len1, SLC.getIntPtrType(), false,
1586 Len1->getName(), ci);
1588 CastToCStr(ci->getOperand(1), *ci),
1589 CastToCStr(ci->getOperand(3), *ci),
1591 ConstantInt::get(Type::Int32Ty,1)
1593 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1595 // The strlen result is the unincremented number of bytes in the string.
1596 if (!ci->use_empty()) {
1597 if (Len->getType() != ci->getType())
1598 Len = CastInst::createIntegerCast(Len, ci->getType(), false,
1599 Len->getName(), ci);
1600 ci->replaceAllUsesWith(Len);
1602 ci->eraseFromParent();
1606 // sprintf(dest,"%c",chr) -> store chr, dest
1607 CastInst* cast = CastInst::createTruncOrBitCast(
1608 ci->getOperand(3), Type::Int8Ty, "char", ci);
1609 new StoreInst(cast, ci->getOperand(1), ci);
1610 GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
1611 ConstantInt::get(Type::Int32Ty,1),ci->getOperand(1)->getName()+".end",
1613 new StoreInst(ConstantInt::get(Type::Int8Ty,0),gep,ci);
1614 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1615 ci->eraseFromParent();
1623 /// This LibCallOptimization will simplify calls to the "fputs" library
1624 /// function. It looks for cases where the result of fputs is not used and the
1625 /// operation can be reduced to something simpler.
1626 /// @brief Simplify the puts library function.
1627 struct VISIBILITY_HIDDEN PutsOptimization : public LibCallOptimization {
1629 /// @brief Default Constructor
1630 PutsOptimization() : LibCallOptimization("fputs",
1631 "Number of 'fputs' calls simplified") {}
1633 /// @brief Make sure that the "fputs" function has the right prototype
1634 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1635 // Just make sure this has 2 arguments
1636 return F->arg_size() == 2;
1639 /// @brief Perform the fputs optimization.
1640 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1641 // If the result is used, none of these optimizations work
1642 if (!ci->use_empty())
1645 // All the optimizations depend on the length of the first argument and the
1646 // fact that it is a constant string array. Check that now
1647 uint64_t len, StartIdx;
1649 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1654 // fputs("",F) -> noop
1658 // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
1659 const Type* FILEptr_type = ci->getOperand(2)->getType();
1660 LoadInst* loadi = new LoadInst(ci->getOperand(1),
1661 ci->getOperand(1)->getName()+".byte",ci);
1662 CastInst* casti = new SExtInst(loadi, Type::Int32Ty,
1663 loadi->getName()+".int", ci);
1664 new CallInst(SLC.get_fputc(FILEptr_type), casti,
1665 ci->getOperand(2), "", ci);
1670 // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
1671 const Type* FILEptr_type = ci->getOperand(2)->getType();
1674 ConstantInt::get(SLC.getIntPtrType(),len),
1675 ConstantInt::get(SLC.getIntPtrType(),1),
1678 new CallInst(SLC.get_fwrite(FILEptr_type), parms, 4, "", ci);
1682 ci->eraseFromParent();
1683 return true; // success
1687 /// This LibCallOptimization will simplify calls to the "isdigit" library
1688 /// function. It simply does range checks the parameter explicitly.
1689 /// @brief Simplify the isdigit library function.
1690 struct VISIBILITY_HIDDEN isdigitOptimization : public LibCallOptimization {
1692 isdigitOptimization() : LibCallOptimization("isdigit",
1693 "Number of 'isdigit' calls simplified") {}
1695 /// @brief Make sure that the "isdigit" function has the right prototype
1696 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1697 // Just make sure this has 1 argument
1698 return (f->arg_size() == 1);
1701 /// @brief Perform the toascii optimization.
1702 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1703 if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
1704 // isdigit(c) -> 0 or 1, if 'c' is constant
1705 uint64_t val = CI->getZExtValue();
1706 if (val >= '0' && val <='9')
1707 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1709 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1710 ci->eraseFromParent();
1714 // isdigit(c) -> (unsigned)c - '0' <= 9
1715 CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
1716 Type::Int32Ty, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
1717 BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
1718 ConstantInt::get(Type::Int32Ty,0x30),
1719 ci->getOperand(1)->getName()+".sub",ci);
1720 ICmpInst* setcond_inst = new ICmpInst(ICmpInst::ICMP_ULE,sub_inst,
1721 ConstantInt::get(Type::Int32Ty,9),
1722 ci->getOperand(1)->getName()+".cmp",ci);
1723 CastInst* c2 = new ZExtInst(setcond_inst, Type::Int32Ty,
1724 ci->getOperand(1)->getName()+".isdigit", ci);
1725 ci->replaceAllUsesWith(c2);
1726 ci->eraseFromParent();
1731 struct VISIBILITY_HIDDEN isasciiOptimization : public LibCallOptimization {
1733 isasciiOptimization()
1734 : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
1736 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1737 return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() &&
1738 F->getReturnType()->isInteger();
1741 /// @brief Perform the isascii optimization.
1742 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1743 // isascii(c) -> (unsigned)c < 128
1744 Value *V = CI->getOperand(1);
1745 Value *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, V,
1746 ConstantInt::get(V->getType(), 128),
1747 V->getName()+".isascii", CI);
1748 if (Cmp->getType() != CI->getType())
1749 Cmp = new BitCastInst(Cmp, CI->getType(), Cmp->getName(), CI);
1750 CI->replaceAllUsesWith(Cmp);
1751 CI->eraseFromParent();
1757 /// This LibCallOptimization will simplify calls to the "toascii" library
1758 /// function. It simply does the corresponding and operation to restrict the
1759 /// range of values to the ASCII character set (0-127).
1760 /// @brief Simplify the toascii library function.
1761 struct VISIBILITY_HIDDEN ToAsciiOptimization : public LibCallOptimization {
1763 /// @brief Default Constructor
1764 ToAsciiOptimization() : LibCallOptimization("toascii",
1765 "Number of 'toascii' calls simplified") {}
1767 /// @brief Make sure that the "fputs" function has the right prototype
1768 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1769 // Just make sure this has 2 arguments
1770 return (f->arg_size() == 1);
1773 /// @brief Perform the toascii optimization.
1774 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1775 // toascii(c) -> (c & 0x7f)
1776 Value* chr = ci->getOperand(1);
1777 BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
1778 ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
1779 ci->replaceAllUsesWith(and_inst);
1780 ci->eraseFromParent();
1785 /// This LibCallOptimization will simplify calls to the "ffs" library
1786 /// calls which find the first set bit in an int, long, or long long. The
1787 /// optimization is to compute the result at compile time if the argument is
1789 /// @brief Simplify the ffs library function.
1790 struct VISIBILITY_HIDDEN FFSOptimization : public LibCallOptimization {
1792 /// @brief Subclass Constructor
1793 FFSOptimization(const char* funcName, const char* description)
1794 : LibCallOptimization(funcName, description) {}
1797 /// @brief Default Constructor
1798 FFSOptimization() : LibCallOptimization("ffs",
1799 "Number of 'ffs' calls simplified") {}
1801 /// @brief Make sure that the "ffs" function has the right prototype
1802 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1803 // Just make sure this has 2 arguments
1804 return F->arg_size() == 1 && F->getReturnType() == Type::Int32Ty;
1807 /// @brief Perform the ffs optimization.
1808 virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
1809 if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
1810 // ffs(cnst) -> bit#
1811 // ffsl(cnst) -> bit#
1812 // ffsll(cnst) -> bit#
1813 uint64_t val = CI->getZExtValue();
1817 while ((val & 1) == 0) {
1822 TheCall->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, result));
1823 TheCall->eraseFromParent();
1827 // ffs(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1828 // ffsl(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1829 // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1830 const Type *ArgType = TheCall->getOperand(1)->getType();
1831 const char *CTTZName;
1832 assert(ArgType->getTypeID() == Type::IntegerTyID &&
1833 "llvm.cttz argument is not an integer?");
1834 unsigned BitWidth = cast<IntegerType>(ArgType)->getBitWidth();
1836 CTTZName = "llvm.cttz.i8";
1837 else if (BitWidth == 16)
1838 CTTZName = "llvm.cttz.i16";
1839 else if (BitWidth == 32)
1840 CTTZName = "llvm.cttz.i32";
1842 assert(BitWidth == 64 && "Unknown bitwidth");
1843 CTTZName = "llvm.cttz.i64";
1846 Constant *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
1848 Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType,
1849 false/*ZExt*/, "tmp", TheCall);
1850 Value *V2 = new CallInst(F, V, "tmp", TheCall);
1851 V2 = CastInst::createIntegerCast(V2, Type::Int32Ty, false/*ZExt*/,
1853 V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::Int32Ty, 1),
1855 Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, V,
1856 Constant::getNullValue(V->getType()), "tmp",
1858 V2 = new SelectInst(Cond, ConstantInt::get(Type::Int32Ty, 0), V2,
1859 TheCall->getName(), TheCall);
1860 TheCall->replaceAllUsesWith(V2);
1861 TheCall->eraseFromParent();
1866 /// This LibCallOptimization will simplify calls to the "ffsl" library
1867 /// calls. It simply uses FFSOptimization for which the transformation is
1869 /// @brief Simplify the ffsl library function.
1870 struct VISIBILITY_HIDDEN FFSLOptimization : public FFSOptimization {
1872 /// @brief Default Constructor
1873 FFSLOptimization() : FFSOptimization("ffsl",
1874 "Number of 'ffsl' calls simplified") {}
1878 /// This LibCallOptimization will simplify calls to the "ffsll" library
1879 /// calls. It simply uses FFSOptimization for which the transformation is
1881 /// @brief Simplify the ffsl library function.
1882 struct VISIBILITY_HIDDEN FFSLLOptimization : public FFSOptimization {
1884 /// @brief Default Constructor
1885 FFSLLOptimization() : FFSOptimization("ffsll",
1886 "Number of 'ffsll' calls simplified") {}
1890 /// This optimizes unary functions that take and return doubles.
1891 struct UnaryDoubleFPOptimizer : public LibCallOptimization {
1892 UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
1893 : LibCallOptimization(Fn, Desc) {}
1895 // Make sure that this function has the right prototype
1896 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1897 return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
1898 F->getReturnType() == Type::DoubleTy;
1901 /// ShrinkFunctionToFloatVersion - If the input to this function is really a
1902 /// float, strength reduce this to a float version of the function,
1903 /// e.g. floor((double)FLT) -> (double)floorf(FLT). This can only be called
1904 /// when the target supports the destination function and where there can be
1905 /// no precision loss.
1906 static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
1907 Constant *(SimplifyLibCalls::*FP)()){
1908 if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
1909 if (Cast->getOperand(0)->getType() == Type::FloatTy) {
1910 Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
1912 New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
1913 CI->replaceAllUsesWith(New);
1914 CI->eraseFromParent();
1915 if (Cast->use_empty())
1916 Cast->eraseFromParent();
1924 struct VISIBILITY_HIDDEN FloorOptimization : public UnaryDoubleFPOptimizer {
1926 : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
1928 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1930 // If this is a float argument passed in, convert to floorf.
1931 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
1934 return false; // opt failed
1938 struct VISIBILITY_HIDDEN CeilOptimization : public UnaryDoubleFPOptimizer {
1940 : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
1942 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1944 // If this is a float argument passed in, convert to ceilf.
1945 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
1948 return false; // opt failed
1952 struct VISIBILITY_HIDDEN RoundOptimization : public UnaryDoubleFPOptimizer {
1954 : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
1956 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1958 // If this is a float argument passed in, convert to roundf.
1959 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
1962 return false; // opt failed
1966 struct VISIBILITY_HIDDEN RintOptimization : public UnaryDoubleFPOptimizer {
1968 : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
1970 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1972 // If this is a float argument passed in, convert to rintf.
1973 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
1976 return false; // opt failed
1980 struct VISIBILITY_HIDDEN NearByIntOptimization : public UnaryDoubleFPOptimizer {
1981 NearByIntOptimization()
1982 : UnaryDoubleFPOptimizer("nearbyint",
1983 "Number of 'nearbyint' calls simplified") {}
1985 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1986 #ifdef HAVE_NEARBYINTF
1987 // If this is a float argument passed in, convert to nearbyintf.
1988 if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
1991 return false; // opt failed
1993 } NearByIntOptimizer;
1995 /// GetConstantStringInfo - This function computes the length of a
1996 /// null-terminated constant array of integers. This function can't rely on the
1997 /// size of the constant array because there could be a null terminator in the
1998 /// middle of the array.
2000 /// We also have to bail out if we find a non-integer constant initializer
2001 /// of one of the elements or if there is no null-terminator. The logic
2002 /// below checks each of these conditions and will return true only if all
2003 /// conditions are met. If the conditions aren't met, this returns false.
2005 /// If successful, the \p Array param is set to the constant array being
2006 /// indexed, the \p Length parameter is set to the length of the null-terminated
2007 /// string pointed to by V, the \p StartIdx value is set to the first
2008 /// element of the Array that V points to, and true is returned.
2009 static bool GetConstantStringInfo(Value *V, ConstantArray *&Array,
2010 uint64_t &Length, uint64_t &StartIdx) {
2011 assert(V != 0 && "Invalid args to GetConstantStringInfo");
2012 // Initialize results.
2018 // If the value is not a GEP instruction nor a constant expression with a
2019 // GEP instruction, then return false because ConstantArray can't occur
2021 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
2023 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
2024 if (CE->getOpcode() != Instruction::GetElementPtr)
2031 // Make sure the GEP has exactly three arguments.
2032 if (GEP->getNumOperands() != 3)
2035 // Check to make sure that the first operand of the GEP is an integer and
2036 // has value 0 so that we are sure we're indexing into the initializer.
2037 if (ConstantInt* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
2043 // If the second index isn't a ConstantInt, then this is a variable index
2044 // into the array. If this occurs, we can't say anything meaningful about
2047 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
2048 StartIdx = CI->getZExtValue();
2052 // The GEP instruction, constant or instruction, must reference a global
2053 // variable that is a constant and is initialized. The referenced constant
2054 // initializer is the array that we'll use for optimization.
2055 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
2056 if (!GV || !GV->isConstant() || !GV->hasInitializer())
2058 Constant *GlobalInit = GV->getInitializer();
2060 // Handle the ConstantAggregateZero case
2061 if (isa<ConstantAggregateZero>(GlobalInit)) {
2062 // This is a degenerate case. The initializer is constant zero so the
2063 // length of the string must be zero.
2068 // Must be a Constant Array
2069 Array = dyn_cast<ConstantArray>(GlobalInit);
2070 if (!Array) return false;
2072 // Get the number of elements in the array
2073 uint64_t NumElts = Array->getType()->getNumElements();
2075 // Traverse the constant array from start_idx (derived above) which is
2076 // the place the GEP refers to in the array.
2079 if (Length >= NumElts)
2080 return false; // The array isn't null terminated.
2082 Constant *Elt = Array->getOperand(Length);
2083 if (ConstantInt *CI = dyn_cast<ConstantInt>(Elt)) {
2084 // Check for the null terminator.
2086 break; // we found end of string
2088 return false; // This array isn't suitable, non-int initializer
2092 // Subtract out the initial value from the length
2094 return true; // success!
2097 /// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
2098 /// inserting the cast before IP, and return the cast.
2099 /// @brief Cast a value to a "C" string.
2100 static Value *CastToCStr(Value *V, Instruction &IP) {
2101 assert(isa<PointerType>(V->getType()) &&
2102 "Can't cast non-pointer type to C string type");
2103 const Type *SBPTy = PointerType::get(Type::Int8Ty);
2104 if (V->getType() != SBPTy)
2105 return new BitCastInst(V, SBPTy, V->getName(), &IP);
2110 // Additional cases that we need to add to this file:
2113 // * cbrt(expN(X)) -> expN(x/3)
2114 // * cbrt(sqrt(x)) -> pow(x,1/6)
2115 // * cbrt(sqrt(x)) -> pow(x,1/9)
2118 // * cos(-x) -> cos(x)
2121 // * exp(log(x)) -> x
2124 // * log(exp(x)) -> x
2125 // * log(x**y) -> y*log(x)
2126 // * log(exp(y)) -> y*log(e)
2127 // * log(exp2(y)) -> y*log(2)
2128 // * log(exp10(y)) -> y*log(10)
2129 // * log(sqrt(x)) -> 0.5*log(x)
2130 // * log(pow(x,y)) -> y*log(x)
2132 // lround, lroundf, lroundl:
2133 // * lround(cnst) -> cnst'
2136 // * memcmp(x,y,l) -> cnst
2137 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
2140 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
2141 // (if s is a global constant array)
2144 // * pow(exp(x),y) -> exp(x*y)
2145 // * pow(sqrt(x),y) -> pow(x,y*0.5)
2146 // * pow(pow(x,y),z)-> pow(x,y*z)
2149 // * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
2151 // round, roundf, roundl:
2152 // * round(cnst) -> cnst'
2155 // * signbit(cnst) -> cnst'
2156 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2158 // sqrt, sqrtf, sqrtl:
2159 // * sqrt(expN(x)) -> expN(x*0.5)
2160 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2161 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2164 // * stpcpy(str, "literal") ->
2165 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
2167 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
2168 // (if c is a constant integer and s is a constant string)
2169 // * strrchr(s1,0) -> strchr(s1,0)
2172 // * strncat(x,y,0) -> x
2173 // * strncat(x,y,0) -> x (if strlen(y) = 0)
2174 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
2177 // * strncpy(d,s,0) -> d
2178 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
2179 // (if s and l are constants)
2182 // * strpbrk(s,a) -> offset_in_for(s,a)
2183 // (if s and a are both constant strings)
2184 // * strpbrk(s,"") -> 0
2185 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
2188 // * strspn(s,a) -> const_int (if both args are constant)
2189 // * strspn("",a) -> 0
2190 // * strspn(s,"") -> 0
2191 // * strcspn(s,a) -> const_int (if both args are constant)
2192 // * strcspn("",a) -> 0
2193 // * strcspn(s,"") -> strlen(a)
2196 // * strstr(x,x) -> x
2197 // * strstr(s1,s2) -> offset_of_s2_in(s1)
2198 // (if s1 and s2 are constant strings)
2201 // * tan(atan(x)) -> x
2203 // trunc, truncf, truncl:
2204 // * trunc(cnst) -> cnst'