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 *Dst = 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.
484 uint64_t SrcLength, StartIdx;
486 if (!GetConstantStringInfo(Src, Arr, SrcLength, StartIdx))
489 // Handle the simple, do-nothing case
490 if (SrcLength == 0) {
491 CI->replaceAllUsesWith(Dst);
492 CI->eraseFromParent();
496 // We need to find the end of the destination string. That's where the
497 // memory is to be moved to. We just generate a call to strlen (further
498 // optimized in another pass).
499 CallInst *DstLen = new CallInst(SLC.get_strlen(), Dst,
500 Dst->getName()+".len", CI);
502 // Now that we have the destination's length, we must index into the
503 // destination's pointer to get the actual memcpy destination (end of
504 // the string .. we're concatenating).
505 Dst = new GetElementPtrInst(Dst, DstLen, Dst->getName()+".indexed", CI);
507 // We have enough information to now generate the memcpy call to
508 // do the concatenation for us.
511 ConstantInt::get(SLC.getIntPtrType(), SrcLength+1), // copy nul term.
512 ConstantInt::get(Type::Int32Ty, 1) // alignment
514 new CallInst(SLC.get_memcpy(), Vals, 4, "", CI);
516 // Finally, substitute the first operand of the strcat call for the
517 // strcat call itself since strcat returns its first operand; and,
518 // kill the strcat CallInst.
519 CI->replaceAllUsesWith(Dst);
520 CI->eraseFromParent();
525 /// This LibCallOptimization will simplify a call to the strchr library
526 /// function. It optimizes out cases where the arguments are both constant
527 /// and the result can be determined statically.
528 /// @brief Simplify the strcmp library function.
529 struct VISIBILITY_HIDDEN StrChrOptimization : public LibCallOptimization {
531 StrChrOptimization() : LibCallOptimization("strchr",
532 "Number of 'strchr' calls simplified") {}
534 /// @brief Make sure that the "strchr" function has the right prototype
535 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
536 const FunctionType *FT = F->getFunctionType();
537 return FT->getNumParams() == 2 &&
538 FT->getReturnType() == PointerType::get(Type::Int8Ty) &&
539 FT->getParamType(0) == FT->getReturnType() &&
540 isa<IntegerType>(FT->getParamType(1));
543 /// @brief Perform the strchr optimizations
544 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
545 // Check that the first argument to strchr is a constant array of sbyte.
546 // If it is, get the length and data, otherwise return false.
547 uint64_t StrLength, StartIdx;
548 ConstantArray *CA = 0;
549 if (!GetConstantStringInfo(CI->getOperand(1), CA, StrLength, StartIdx))
552 // If the second operand is not constant, just lower this to memchr since we
553 // know the length of the input string.
554 ConstantInt *CSI = dyn_cast<ConstantInt>(CI->getOperand(2));
559 ConstantInt::get(SLC.getIntPtrType(), StrLength+1)
561 CI->replaceAllUsesWith(new CallInst(SLC.get_memchr(), Args, 3,
563 CI->eraseFromParent();
567 // Get the character we're looking for
568 int64_t CharValue = CSI->getSExtValue();
570 if (StrLength == 0) {
571 // If the length of the string is zero, and we are searching for zero,
572 // return the input pointer.
573 if (CharValue == 0) {
574 CI->replaceAllUsesWith(CI->getOperand(1));
576 // Otherwise, char wasn't found.
577 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
579 CI->eraseFromParent();
583 // Compute the offset
586 assert(i <= StrLength && "Didn't find null terminator?");
587 if (ConstantInt *C = dyn_cast<ConstantInt>(CA->getOperand(i+StartIdx))) {
588 // Did we find our match?
589 if (C->getSExtValue() == CharValue)
592 // We found the end of the string. strchr returns null.
593 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
594 CI->eraseFromParent();
601 // strchr(s+n,c) -> gep(s+n+i,c)
602 // (if c is a constant integer and s is a constant string)
603 Value *Idx = ConstantInt::get(Type::Int64Ty, i);
604 Value *GEP = new GetElementPtrInst(CI->getOperand(1), Idx,
605 CI->getOperand(1)->getName() +
607 CI->replaceAllUsesWith(GEP);
608 CI->eraseFromParent();
613 /// This LibCallOptimization will simplify a call to the strcmp library
614 /// function. It optimizes out cases where one or both arguments are constant
615 /// and the result can be determined statically.
616 /// @brief Simplify the strcmp library function.
617 struct VISIBILITY_HIDDEN StrCmpOptimization : public LibCallOptimization {
619 StrCmpOptimization() : LibCallOptimization("strcmp",
620 "Number of 'strcmp' calls simplified") {}
622 /// @brief Make sure that the "strcmp" function has the right prototype
623 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
624 return F->getReturnType() == Type::Int32Ty && F->arg_size() == 2;
627 /// @brief Perform the strcmp optimization
628 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
629 // First, check to see if src and destination are the same. If they are,
630 // then the optimization is to replace the CallInst with a constant 0
631 // because the call is a no-op.
632 Value* s1 = ci->getOperand(1);
633 Value* s2 = ci->getOperand(2);
636 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
637 ci->eraseFromParent();
641 bool isstr_1 = false;
642 uint64_t len_1 = 0, StartIdx;
644 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
647 // strcmp("",x) -> *x
649 new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
651 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
652 ci->getName()+".int", ci);
653 ci->replaceAllUsesWith(cast);
654 ci->eraseFromParent();
659 bool isstr_2 = false;
662 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
665 // strcmp(x,"") -> *x
667 new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
669 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
670 ci->getName()+".int", ci);
671 ci->replaceAllUsesWith(cast);
672 ci->eraseFromParent();
677 if (isstr_1 && isstr_2) {
678 // strcmp(x,y) -> cnst (if both x and y are constant strings)
679 std::string str1 = A1->getAsString();
680 std::string str2 = A2->getAsString();
681 int result = strcmp(str1.c_str(), str2.c_str());
682 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
683 ci->eraseFromParent();
690 /// This LibCallOptimization will simplify a call to the strncmp library
691 /// function. It optimizes out cases where one or both arguments are constant
692 /// and the result can be determined statically.
693 /// @brief Simplify the strncmp library function.
694 struct VISIBILITY_HIDDEN StrNCmpOptimization : public LibCallOptimization {
696 StrNCmpOptimization() : LibCallOptimization("strncmp",
697 "Number of 'strncmp' calls simplified") {}
699 /// @brief Make sure that the "strncmp" function has the right prototype
700 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
701 if (f->getReturnType() == Type::Int32Ty && f->arg_size() == 3)
706 /// @brief Perform the strncpy optimization
707 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
708 // First, check to see if src and destination are the same. If they are,
709 // then the optimization is to replace the CallInst with a constant 0
710 // because the call is a no-op.
711 Value* s1 = ci->getOperand(1);
712 Value* s2 = ci->getOperand(2);
714 // strncmp(x,x,l) -> 0
715 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
716 ci->eraseFromParent();
720 // Check the length argument, if it is Constant zero then the strings are
722 uint64_t len_arg = 0;
723 bool len_arg_is_const = false;
724 if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
725 len_arg_is_const = true;
726 len_arg = len_CI->getZExtValue();
728 // strncmp(x,y,0) -> 0
729 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
730 ci->eraseFromParent();
735 bool isstr_1 = false;
736 uint64_t len_1 = 0, StartIdx;
738 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
741 // strncmp("",x) -> *x
742 LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
744 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
745 ci->getName()+".int", ci);
746 ci->replaceAllUsesWith(cast);
747 ci->eraseFromParent();
752 bool isstr_2 = false;
755 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
758 // strncmp(x,"") -> *x
759 LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
761 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
762 ci->getName()+".int", ci);
763 ci->replaceAllUsesWith(cast);
764 ci->eraseFromParent();
769 if (isstr_1 && isstr_2 && len_arg_is_const) {
770 // strncmp(x,y,const) -> constant
771 std::string str1 = A1->getAsString();
772 std::string str2 = A2->getAsString();
773 int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
774 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
775 ci->eraseFromParent();
782 /// This LibCallOptimization will simplify a call to the strcpy library
783 /// function. Two optimizations are possible:
784 /// (1) If src and dest are the same and not volatile, just return dest
785 /// (2) If the src is a constant then we can convert to llvm.memmove
786 /// @brief Simplify the strcpy library function.
787 struct VISIBILITY_HIDDEN StrCpyOptimization : public LibCallOptimization {
789 StrCpyOptimization() : LibCallOptimization("strcpy",
790 "Number of 'strcpy' calls simplified") {}
792 /// @brief Make sure that the "strcpy" function has the right prototype
793 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
794 if (f->getReturnType() == PointerType::get(Type::Int8Ty))
795 if (f->arg_size() == 2) {
796 Function::const_arg_iterator AI = f->arg_begin();
797 if (AI++->getType() == PointerType::get(Type::Int8Ty))
798 if (AI->getType() == PointerType::get(Type::Int8Ty)) {
799 // Indicate this is a suitable call type.
806 /// @brief Perform the strcpy optimization
807 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
808 // First, check to see if src and destination are the same. If they are,
809 // then the optimization is to replace the CallInst with the destination
810 // because the call is a no-op. Note that this corresponds to the
811 // degenerate strcpy(X,X) case which should have "undefined" results
812 // according to the C specification. However, it occurs sometimes and
813 // we optimize it as a no-op.
814 Value* dest = ci->getOperand(1);
815 Value* src = ci->getOperand(2);
817 ci->replaceAllUsesWith(dest);
818 ci->eraseFromParent();
822 // Get the length of the constant string referenced by the second operand,
823 // the "src" parameter. Fail the optimization if we can't get the length
824 // (note that GetConstantStringInfo does lots of checks to make sure this
826 uint64_t len, StartIdx;
828 if (!GetConstantStringInfo(ci->getOperand(2), A, len, StartIdx))
831 // If the constant string's length is zero we can optimize this by just
832 // doing a store of 0 at the first byte of the destination
834 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
835 ci->replaceAllUsesWith(dest);
836 ci->eraseFromParent();
840 // Increment the length because we actually want to memcpy the null
841 // terminator as well.
844 // We have enough information to now generate the memcpy call to
845 // do the concatenation for us.
848 ConstantInt::get(SLC.getIntPtrType(),len), // length
849 ConstantInt::get(Type::Int32Ty, 1) // alignment
851 new CallInst(SLC.get_memcpy(), vals, 4, "", ci);
853 // Finally, substitute the first operand of the strcat call for the
854 // strcat call itself since strcat returns its first operand; and,
855 // kill the strcat CallInst.
856 ci->replaceAllUsesWith(dest);
857 ci->eraseFromParent();
862 /// This LibCallOptimization will simplify a call to the strlen library
863 /// function by replacing it with a constant value if the string provided to
864 /// it is a constant array.
865 /// @brief Simplify the strlen library function.
866 struct VISIBILITY_HIDDEN StrLenOptimization : public LibCallOptimization {
867 StrLenOptimization() : LibCallOptimization("strlen",
868 "Number of 'strlen' calls simplified") {}
870 /// @brief Make sure that the "strlen" function has the right prototype
871 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
873 if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
874 if (f->arg_size() == 1)
875 if (Function::const_arg_iterator AI = f->arg_begin())
876 if (AI->getType() == PointerType::get(Type::Int8Ty))
881 /// @brief Perform the strlen optimization
882 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
884 // Make sure we're dealing with an sbyte* here.
885 Value* str = ci->getOperand(1);
886 if (str->getType() != PointerType::get(Type::Int8Ty))
889 // Does the call to strlen have exactly one use?
891 // Is that single use a icmp operator?
892 if (ICmpInst* bop = dyn_cast<ICmpInst>(ci->use_back()))
893 // Is it compared against a constant integer?
894 if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
896 // Get the value the strlen result is compared to
897 uint64_t val = CI->getZExtValue();
899 // If its compared against length 0 with == or !=
901 (bop->getPredicate() == ICmpInst::ICMP_EQ ||
902 bop->getPredicate() == ICmpInst::ICMP_NE))
904 // strlen(x) != 0 -> *x != 0
905 // strlen(x) == 0 -> *x == 0
906 LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
907 ICmpInst* rbop = new ICmpInst(bop->getPredicate(), load,
908 ConstantInt::get(Type::Int8Ty,0),
909 bop->getName()+".strlen", ci);
910 bop->replaceAllUsesWith(rbop);
911 bop->eraseFromParent();
912 ci->eraseFromParent();
917 // Get the length of the constant string operand
918 uint64_t len = 0, StartIdx;
920 if (!GetConstantStringInfo(ci->getOperand(1), A, len, StartIdx))
923 // strlen("xyz") -> 3 (for example)
924 const Type *Ty = SLC.getTargetData()->getIntPtrType();
925 ci->replaceAllUsesWith(ConstantInt::get(Ty, len));
927 ci->eraseFromParent();
932 /// IsOnlyUsedInEqualsComparison - Return true if it only matters that the value
933 /// is equal or not-equal to zero.
934 static bool IsOnlyUsedInEqualsZeroComparison(Instruction *I) {
935 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
937 Instruction *User = cast<Instruction>(*UI);
938 if (ICmpInst *IC = dyn_cast<ICmpInst>(User)) {
939 if ((IC->getPredicate() == ICmpInst::ICMP_NE ||
940 IC->getPredicate() == ICmpInst::ICMP_EQ) &&
941 isa<Constant>(IC->getOperand(1)) &&
942 cast<Constant>(IC->getOperand(1))->isNullValue())
944 } else if (CastInst *CI = dyn_cast<CastInst>(User))
945 if (CI->getType() == Type::Int1Ty)
947 // Unknown instruction.
953 /// This memcmpOptimization will simplify a call to the memcmp library
955 struct VISIBILITY_HIDDEN memcmpOptimization : public LibCallOptimization {
956 /// @brief Default Constructor
958 : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
960 /// @brief Make sure that the "memcmp" function has the right prototype
961 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
962 Function::const_arg_iterator AI = F->arg_begin();
963 if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
964 if (!isa<PointerType>((++AI)->getType())) return false;
965 if (!(++AI)->getType()->isInteger()) return false;
966 if (!F->getReturnType()->isInteger()) return false;
970 /// Because of alignment and instruction information that we don't have, we
971 /// leave the bulk of this to the code generators.
973 /// Note that we could do much more if we could force alignment on otherwise
974 /// small aligned allocas, or if we could indicate that loads have a small
976 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
977 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
979 // If the two operands are the same, return zero.
981 // memcmp(s,s,x) -> 0
982 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
983 CI->eraseFromParent();
987 // Make sure we have a constant length.
988 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
989 if (!LenC) return false;
990 uint64_t Len = LenC->getZExtValue();
992 // If the length is zero, this returns 0.
995 // memcmp(s1,s2,0) -> 0
996 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
997 CI->eraseFromParent();
1000 // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
1001 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1002 CastInst *Op1Cast = CastInst::create(
1003 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1004 CastInst *Op2Cast = CastInst::create(
1005 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1006 Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
1007 Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
1008 Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
1009 if (RV->getType() != CI->getType())
1010 RV = CastInst::createIntegerCast(RV, CI->getType(), false,
1012 CI->replaceAllUsesWith(RV);
1013 CI->eraseFromParent();
1017 if (IsOnlyUsedInEqualsZeroComparison(CI)) {
1018 // TODO: IF both are aligned, use a short load/compare.
1020 // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
1021 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1022 CastInst *Op1Cast = CastInst::create(
1023 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1024 CastInst *Op2Cast = CastInst::create(
1025 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1026 Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
1027 Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
1028 Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
1029 CI->getName()+".d1", CI);
1030 Constant *One = ConstantInt::get(Type::Int32Ty, 1);
1031 Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
1032 Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
1033 Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
1034 Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
1035 Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
1036 CI->getName()+".d1", CI);
1037 Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
1038 if (Or->getType() != CI->getType())
1039 Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/,
1041 CI->replaceAllUsesWith(Or);
1042 CI->eraseFromParent();
1055 /// This LibCallOptimization will simplify a call to the memcpy library
1056 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1057 /// bytes depending on the length of the string and the alignment. Additional
1058 /// optimizations are possible in code generation (sequence of immediate store)
1059 /// @brief Simplify the memcpy library function.
1060 struct VISIBILITY_HIDDEN LLVMMemCpyMoveOptzn : public LibCallOptimization {
1061 LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
1062 : LibCallOptimization(fname, desc) {}
1064 /// @brief Make sure that the "memcpy" function has the right prototype
1065 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
1066 // Just make sure this has 4 arguments per LLVM spec.
1067 return (f->arg_size() == 4);
1070 /// Because of alignment and instruction information that we don't have, we
1071 /// leave the bulk of this to the code generators. The optimization here just
1072 /// deals with a few degenerate cases where the length of the string and the
1073 /// alignment match the sizes of our intrinsic types so we can do a load and
1074 /// store instead of the memcpy call.
1075 /// @brief Perform the memcpy optimization.
1076 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
1077 // Make sure we have constant int values to work with
1078 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1081 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1085 // If the length is larger than the alignment, we can't optimize
1086 uint64_t len = LEN->getZExtValue();
1087 uint64_t alignment = ALIGN->getZExtValue();
1089 alignment = 1; // Alignment 0 is identity for alignment 1
1090 if (len > alignment)
1093 // Get the type we will cast to, based on size of the string
1094 Value* dest = ci->getOperand(1);
1095 Value* src = ci->getOperand(2);
1096 const Type* castType = 0;
1100 // memcpy(d,s,0,a) -> noop
1101 ci->eraseFromParent();
1103 case 1: castType = Type::Int8Ty; break;
1104 case 2: castType = Type::Int16Ty; break;
1105 case 4: castType = Type::Int32Ty; break;
1106 case 8: castType = Type::Int64Ty; break;
1111 // Cast source and dest to the right sized primitive and then load/store
1112 CastInst* SrcCast = CastInst::create(Instruction::BitCast,
1113 src, PointerType::get(castType), src->getName()+".cast", ci);
1114 CastInst* DestCast = CastInst::create(Instruction::BitCast,
1115 dest, PointerType::get(castType),dest->getName()+".cast", ci);
1116 LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
1117 new StoreInst(LI, DestCast, ci);
1118 ci->eraseFromParent();
1123 /// This LibCallOptimization will simplify a call to the memcpy/memmove library
1125 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
1126 "Number of 'llvm.memcpy' calls simplified");
1127 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
1128 "Number of 'llvm.memcpy' calls simplified");
1129 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
1130 "Number of 'llvm.memmove' calls simplified");
1131 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
1132 "Number of 'llvm.memmove' calls simplified");
1134 /// This LibCallOptimization will simplify a call to the memset library
1135 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1136 /// bytes depending on the length argument.
1137 struct VISIBILITY_HIDDEN LLVMMemSetOptimization : public LibCallOptimization {
1138 /// @brief Default Constructor
1139 LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
1140 "Number of 'llvm.memset' calls simplified") {}
1142 /// @brief Make sure that the "memset" function has the right prototype
1143 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
1144 // Just make sure this has 3 arguments per LLVM spec.
1145 return F->arg_size() == 4;
1148 /// Because of alignment and instruction information that we don't have, we
1149 /// leave the bulk of this to the code generators. The optimization here just
1150 /// deals with a few degenerate cases where the length parameter is constant
1151 /// and the alignment matches the sizes of our intrinsic types so we can do
1152 /// store instead of the memcpy call. Other calls are transformed into the
1153 /// llvm.memset intrinsic.
1154 /// @brief Perform the memset optimization.
1155 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
1156 // Make sure we have constant int values to work with
1157 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1160 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1164 // Extract the length and alignment
1165 uint64_t len = LEN->getZExtValue();
1166 uint64_t alignment = ALIGN->getZExtValue();
1168 // Alignment 0 is identity for alignment 1
1172 // If the length is zero, this is a no-op
1174 // memset(d,c,0,a) -> noop
1175 ci->eraseFromParent();
1179 // If the length is larger than the alignment, we can't optimize
1180 if (len > alignment)
1183 // Make sure we have a constant ubyte to work with so we can extract
1184 // the value to be filled.
1185 ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
1188 if (FILL->getType() != Type::Int8Ty)
1191 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
1193 // Extract the fill character
1194 uint64_t fill_char = FILL->getZExtValue();
1195 uint64_t fill_value = fill_char;
1197 // Get the type we will cast to, based on size of memory area to fill, and
1198 // and the value we will store there.
1199 Value* dest = ci->getOperand(1);
1200 const Type* castType = 0;
1203 castType = Type::Int8Ty;
1206 castType = Type::Int16Ty;
1207 fill_value |= fill_char << 8;
1210 castType = Type::Int32Ty;
1211 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1214 castType = Type::Int64Ty;
1215 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1216 fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
1217 fill_value |= fill_char << 56;
1223 // Cast dest to the right sized primitive and then load/store
1224 CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType),
1225 dest->getName()+".cast", ci);
1226 new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
1227 ci->eraseFromParent();
1232 LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
1233 LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
1236 /// This LibCallOptimization will simplify calls to the "pow" library
1237 /// function. It looks for cases where the result of pow is well known and
1238 /// substitutes the appropriate value.
1239 /// @brief Simplify the pow library function.
1240 struct VISIBILITY_HIDDEN PowOptimization : public LibCallOptimization {
1242 /// @brief Default Constructor
1243 PowOptimization() : LibCallOptimization("pow",
1244 "Number of 'pow' calls simplified") {}
1246 /// @brief Make sure that the "pow" function has the right prototype
1247 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1248 // Just make sure this has 2 arguments
1249 return (f->arg_size() == 2);
1252 /// @brief Perform the pow optimization.
1253 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1254 const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
1255 Value* base = ci->getOperand(1);
1256 Value* expn = ci->getOperand(2);
1257 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
1258 double Op1V = Op1->getValue();
1260 // pow(1.0,x) -> 1.0
1261 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1262 ci->eraseFromParent();
1265 } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
1266 double Op2V = Op2->getValue();
1268 // pow(x,0.0) -> 1.0
1269 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1270 ci->eraseFromParent();
1272 } else if (Op2V == 0.5) {
1273 // pow(x,0.5) -> sqrt(x)
1274 CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
1275 ci->getName()+".pow",ci);
1276 ci->replaceAllUsesWith(sqrt_inst);
1277 ci->eraseFromParent();
1279 } else if (Op2V == 1.0) {
1281 ci->replaceAllUsesWith(base);
1282 ci->eraseFromParent();
1284 } else if (Op2V == -1.0) {
1285 // pow(x,-1.0) -> 1.0/x
1286 BinaryOperator* div_inst= BinaryOperator::createFDiv(
1287 ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
1288 ci->replaceAllUsesWith(div_inst);
1289 ci->eraseFromParent();
1293 return false; // opt failed
1297 /// This LibCallOptimization will simplify calls to the "printf" library
1298 /// function. It looks for cases where the result of printf is not used and the
1299 /// operation can be reduced to something simpler.
1300 /// @brief Simplify the printf library function.
1301 struct VISIBILITY_HIDDEN PrintfOptimization : public LibCallOptimization {
1303 /// @brief Default Constructor
1304 PrintfOptimization() : LibCallOptimization("printf",
1305 "Number of 'printf' calls simplified") {}
1307 /// @brief Make sure that the "printf" function has the right prototype
1308 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1309 // Just make sure this has at least 1 arguments
1310 return (f->arg_size() >= 1);
1313 /// @brief Perform the printf optimization.
1314 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1315 // If the call has more than 2 operands, we can't optimize it
1316 if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
1319 // If the result of the printf call is used, none of these optimizations
1321 if (!ci->use_empty())
1324 // All the optimizations depend on the length of the first argument and the
1325 // fact that it is a constant string array. Check that now
1326 uint64_t len, StartIdx;
1327 ConstantArray* CA = 0;
1328 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1331 if (len != 2 && len != 3)
1334 // The first character has to be a %
1335 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1336 if (CI->getZExtValue() != '%')
1339 // Get the second character and switch on its value
1340 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1341 switch (CI->getZExtValue()) {
1345 dyn_cast<ConstantInt>(CA->getOperand(2))->getZExtValue() != '\n')
1348 // printf("%s\n",str) -> puts(str)
1349 std::vector<Value*> args;
1350 new CallInst(SLC.get_puts(), CastToCStr(ci->getOperand(2), *ci),
1352 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1357 // printf("%c",c) -> putchar(c)
1361 CastInst *Char = CastInst::createSExtOrBitCast(
1362 ci->getOperand(2), Type::Int32Ty, CI->getName()+".int", ci);
1363 new CallInst(SLC.get_putchar(), Char, "", ci);
1364 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, 1));
1370 ci->eraseFromParent();
1375 /// This LibCallOptimization will simplify calls to the "fprintf" library
1376 /// function. It looks for cases where the result of fprintf is not used and the
1377 /// operation can be reduced to something simpler.
1378 /// @brief Simplify the fprintf library function.
1379 struct VISIBILITY_HIDDEN FPrintFOptimization : public LibCallOptimization {
1381 /// @brief Default Constructor
1382 FPrintFOptimization() : LibCallOptimization("fprintf",
1383 "Number of 'fprintf' calls simplified") {}
1385 /// @brief Make sure that the "fprintf" function has the right prototype
1386 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1387 // Just make sure this has at least 2 arguments
1388 return (f->arg_size() >= 2);
1391 /// @brief Perform the fprintf optimization.
1392 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1393 // If the call has more than 3 operands, we can't optimize it
1394 if (ci->getNumOperands() > 4 || ci->getNumOperands() <= 2)
1397 // If the result of the fprintf call is used, none of these optimizations
1399 if (!ci->use_empty())
1402 // All the optimizations depend on the length of the second argument and the
1403 // fact that it is a constant string array. Check that now
1404 uint64_t len, StartIdx;
1405 ConstantArray* CA = 0;
1406 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1409 if (ci->getNumOperands() == 3) {
1410 // Make sure there's no % in the constant array
1411 for (unsigned i = 0; i < len; ++i) {
1412 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1413 // Check for the null terminator
1414 if (CI->getZExtValue() == '%')
1415 return false; // we found end of string
1421 // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
1422 const Type* FILEptr_type = ci->getOperand(1)->getType();
1424 // Make sure that the fprintf() and fwrite() functions both take the
1425 // same type of char pointer.
1426 if (ci->getOperand(2)->getType() != PointerType::get(Type::Int8Ty))
1431 ConstantInt::get(SLC.getIntPtrType(),len),
1432 ConstantInt::get(SLC.getIntPtrType(),1),
1435 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4, ci->getName(), ci);
1436 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1437 ci->eraseFromParent();
1441 // The remaining optimizations require the format string to be length 2
1446 // The first character has to be a %
1447 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1448 if (CI->getZExtValue() != '%')
1451 // Get the second character and switch on its value
1452 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1453 switch (CI->getZExtValue()) {
1456 uint64_t len, StartIdx;
1457 ConstantArray* CA = 0;
1458 if (GetConstantStringInfo(ci->getOperand(3), CA, len, StartIdx)) {
1459 // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
1460 const Type* FILEptr_type = ci->getOperand(1)->getType();
1462 CastToCStr(ci->getOperand(3), *ci),
1463 ConstantInt::get(SLC.getIntPtrType(), len),
1464 ConstantInt::get(SLC.getIntPtrType(), 1),
1467 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4,ci->getName(), ci);
1468 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1470 // fprintf(file,"%s",str) -> fputs(str,file)
1471 const Type* FILEptr_type = ci->getOperand(1)->getType();
1472 new CallInst(SLC.get_fputs(FILEptr_type),
1473 CastToCStr(ci->getOperand(3), *ci),
1474 ci->getOperand(1), ci->getName(),ci);
1475 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1481 // fprintf(file,"%c",c) -> fputc(c,file)
1482 const Type* FILEptr_type = ci->getOperand(1)->getType();
1483 CastInst* cast = CastInst::createSExtOrBitCast(
1484 ci->getOperand(3), Type::Int32Ty, CI->getName()+".int", ci);
1485 new CallInst(SLC.get_fputc(FILEptr_type), cast,ci->getOperand(1),"",ci);
1486 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1492 ci->eraseFromParent();
1497 /// This LibCallOptimization will simplify calls to the "sprintf" library
1498 /// function. It looks for cases where the result of sprintf is not used and the
1499 /// operation can be reduced to something simpler.
1500 /// @brief Simplify the sprintf library function.
1501 struct VISIBILITY_HIDDEN SPrintFOptimization : public LibCallOptimization {
1503 /// @brief Default Constructor
1504 SPrintFOptimization() : LibCallOptimization("sprintf",
1505 "Number of 'sprintf' calls simplified") {}
1507 /// @brief Make sure that the "fprintf" function has the right prototype
1508 virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
1509 // Just make sure this has at least 2 arguments
1510 return (f->getReturnType() == Type::Int32Ty && f->arg_size() >= 2);
1513 /// @brief Perform the sprintf optimization.
1514 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1515 // If the call has more than 3 operands, we can't optimize it
1516 if (ci->getNumOperands() > 4 || ci->getNumOperands() < 3)
1519 // All the optimizations depend on the length of the second argument and the
1520 // fact that it is a constant string array. Check that now
1521 uint64_t len, StartIdx;
1522 ConstantArray* CA = 0;
1523 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1526 if (ci->getNumOperands() == 3) {
1528 // If the length is 0, we just need to store a null byte
1529 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
1530 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1531 ci->eraseFromParent();
1535 // Make sure there's no % in the constant array
1536 for (unsigned i = 0; i < len; ++i) {
1537 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1538 // Check for the null terminator
1539 if (CI->getZExtValue() == '%')
1540 return false; // we found a %, can't optimize
1542 return false; // initializer is not constant int, can't optimize
1546 // Increment length because we want to copy the null byte too
1549 // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
1553 ConstantInt::get(SLC.getIntPtrType(),len),
1554 ConstantInt::get(Type::Int32Ty, 1)
1556 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1557 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1558 ci->eraseFromParent();
1562 // The remaining optimizations require the format string to be length 2
1567 // The first character has to be a %
1568 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1569 if (CI->getZExtValue() != '%')
1572 // Get the second character and switch on its value
1573 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1574 switch (CI->getZExtValue()) {
1576 // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1577 Value *Len = new CallInst(SLC.get_strlen(),
1578 CastToCStr(ci->getOperand(3), *ci),
1579 ci->getOperand(3)->getName()+".len", ci);
1580 Value *Len1 = BinaryOperator::createAdd(Len,
1581 ConstantInt::get(Len->getType(), 1),
1582 Len->getName()+"1", ci);
1583 if (Len1->getType() != SLC.getIntPtrType())
1584 Len1 = CastInst::createIntegerCast(Len1, SLC.getIntPtrType(), false,
1585 Len1->getName(), ci);
1587 CastToCStr(ci->getOperand(1), *ci),
1588 CastToCStr(ci->getOperand(3), *ci),
1590 ConstantInt::get(Type::Int32Ty,1)
1592 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1594 // The strlen result is the unincremented number of bytes in the string.
1595 if (!ci->use_empty()) {
1596 if (Len->getType() != ci->getType())
1597 Len = CastInst::createIntegerCast(Len, ci->getType(), false,
1598 Len->getName(), ci);
1599 ci->replaceAllUsesWith(Len);
1601 ci->eraseFromParent();
1605 // sprintf(dest,"%c",chr) -> store chr, dest
1606 CastInst* cast = CastInst::createTruncOrBitCast(
1607 ci->getOperand(3), Type::Int8Ty, "char", ci);
1608 new StoreInst(cast, ci->getOperand(1), ci);
1609 GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
1610 ConstantInt::get(Type::Int32Ty,1),ci->getOperand(1)->getName()+".end",
1612 new StoreInst(ConstantInt::get(Type::Int8Ty,0),gep,ci);
1613 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1614 ci->eraseFromParent();
1622 /// This LibCallOptimization will simplify calls to the "fputs" library
1623 /// function. It looks for cases where the result of fputs is not used and the
1624 /// operation can be reduced to something simpler.
1625 /// @brief Simplify the puts library function.
1626 struct VISIBILITY_HIDDEN PutsOptimization : public LibCallOptimization {
1628 /// @brief Default Constructor
1629 PutsOptimization() : LibCallOptimization("fputs",
1630 "Number of 'fputs' calls simplified") {}
1632 /// @brief Make sure that the "fputs" function has the right prototype
1633 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1634 // Just make sure this has 2 arguments
1635 return F->arg_size() == 2;
1638 /// @brief Perform the fputs optimization.
1639 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1640 // If the result is used, none of these optimizations work
1641 if (!ci->use_empty())
1644 // All the optimizations depend on the length of the first argument and the
1645 // fact that it is a constant string array. Check that now
1646 uint64_t len, StartIdx;
1648 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1653 // fputs("",F) -> noop
1657 // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
1658 const Type* FILEptr_type = ci->getOperand(2)->getType();
1659 LoadInst* loadi = new LoadInst(ci->getOperand(1),
1660 ci->getOperand(1)->getName()+".byte",ci);
1661 CastInst* casti = new SExtInst(loadi, Type::Int32Ty,
1662 loadi->getName()+".int", ci);
1663 new CallInst(SLC.get_fputc(FILEptr_type), casti,
1664 ci->getOperand(2), "", ci);
1669 // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
1670 const Type* FILEptr_type = ci->getOperand(2)->getType();
1673 ConstantInt::get(SLC.getIntPtrType(),len),
1674 ConstantInt::get(SLC.getIntPtrType(),1),
1677 new CallInst(SLC.get_fwrite(FILEptr_type), parms, 4, "", ci);
1681 ci->eraseFromParent();
1682 return true; // success
1686 /// This LibCallOptimization will simplify calls to the "isdigit" library
1687 /// function. It simply does range checks the parameter explicitly.
1688 /// @brief Simplify the isdigit library function.
1689 struct VISIBILITY_HIDDEN isdigitOptimization : public LibCallOptimization {
1691 isdigitOptimization() : LibCallOptimization("isdigit",
1692 "Number of 'isdigit' calls simplified") {}
1694 /// @brief Make sure that the "isdigit" function has the right prototype
1695 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1696 // Just make sure this has 1 argument
1697 return (f->arg_size() == 1);
1700 /// @brief Perform the toascii optimization.
1701 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1702 if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
1703 // isdigit(c) -> 0 or 1, if 'c' is constant
1704 uint64_t val = CI->getZExtValue();
1705 if (val >= '0' && val <='9')
1706 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1708 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1709 ci->eraseFromParent();
1713 // isdigit(c) -> (unsigned)c - '0' <= 9
1714 CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
1715 Type::Int32Ty, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
1716 BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
1717 ConstantInt::get(Type::Int32Ty,0x30),
1718 ci->getOperand(1)->getName()+".sub",ci);
1719 ICmpInst* setcond_inst = new ICmpInst(ICmpInst::ICMP_ULE,sub_inst,
1720 ConstantInt::get(Type::Int32Ty,9),
1721 ci->getOperand(1)->getName()+".cmp",ci);
1722 CastInst* c2 = new ZExtInst(setcond_inst, Type::Int32Ty,
1723 ci->getOperand(1)->getName()+".isdigit", ci);
1724 ci->replaceAllUsesWith(c2);
1725 ci->eraseFromParent();
1730 struct VISIBILITY_HIDDEN isasciiOptimization : public LibCallOptimization {
1732 isasciiOptimization()
1733 : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
1735 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1736 return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() &&
1737 F->getReturnType()->isInteger();
1740 /// @brief Perform the isascii optimization.
1741 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1742 // isascii(c) -> (unsigned)c < 128
1743 Value *V = CI->getOperand(1);
1744 Value *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, V,
1745 ConstantInt::get(V->getType(), 128),
1746 V->getName()+".isascii", CI);
1747 if (Cmp->getType() != CI->getType())
1748 Cmp = new BitCastInst(Cmp, CI->getType(), Cmp->getName(), CI);
1749 CI->replaceAllUsesWith(Cmp);
1750 CI->eraseFromParent();
1756 /// This LibCallOptimization will simplify calls to the "toascii" library
1757 /// function. It simply does the corresponding and operation to restrict the
1758 /// range of values to the ASCII character set (0-127).
1759 /// @brief Simplify the toascii library function.
1760 struct VISIBILITY_HIDDEN ToAsciiOptimization : public LibCallOptimization {
1762 /// @brief Default Constructor
1763 ToAsciiOptimization() : LibCallOptimization("toascii",
1764 "Number of 'toascii' calls simplified") {}
1766 /// @brief Make sure that the "fputs" function has the right prototype
1767 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1768 // Just make sure this has 2 arguments
1769 return (f->arg_size() == 1);
1772 /// @brief Perform the toascii optimization.
1773 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1774 // toascii(c) -> (c & 0x7f)
1775 Value* chr = ci->getOperand(1);
1776 BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
1777 ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
1778 ci->replaceAllUsesWith(and_inst);
1779 ci->eraseFromParent();
1784 /// This LibCallOptimization will simplify calls to the "ffs" library
1785 /// calls which find the first set bit in an int, long, or long long. The
1786 /// optimization is to compute the result at compile time if the argument is
1788 /// @brief Simplify the ffs library function.
1789 struct VISIBILITY_HIDDEN FFSOptimization : public LibCallOptimization {
1791 /// @brief Subclass Constructor
1792 FFSOptimization(const char* funcName, const char* description)
1793 : LibCallOptimization(funcName, description) {}
1796 /// @brief Default Constructor
1797 FFSOptimization() : LibCallOptimization("ffs",
1798 "Number of 'ffs' calls simplified") {}
1800 /// @brief Make sure that the "ffs" function has the right prototype
1801 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1802 // Just make sure this has 2 arguments
1803 return F->arg_size() == 1 && F->getReturnType() == Type::Int32Ty;
1806 /// @brief Perform the ffs optimization.
1807 virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
1808 if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
1809 // ffs(cnst) -> bit#
1810 // ffsl(cnst) -> bit#
1811 // ffsll(cnst) -> bit#
1812 uint64_t val = CI->getZExtValue();
1816 while ((val & 1) == 0) {
1821 TheCall->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, result));
1822 TheCall->eraseFromParent();
1826 // ffs(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1827 // ffsl(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1828 // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1829 const Type *ArgType = TheCall->getOperand(1)->getType();
1830 const char *CTTZName;
1831 assert(ArgType->getTypeID() == Type::IntegerTyID &&
1832 "llvm.cttz argument is not an integer?");
1833 unsigned BitWidth = cast<IntegerType>(ArgType)->getBitWidth();
1835 CTTZName = "llvm.cttz.i8";
1836 else if (BitWidth == 16)
1837 CTTZName = "llvm.cttz.i16";
1838 else if (BitWidth == 32)
1839 CTTZName = "llvm.cttz.i32";
1841 assert(BitWidth == 64 && "Unknown bitwidth");
1842 CTTZName = "llvm.cttz.i64";
1845 Constant *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
1847 Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType,
1848 false/*ZExt*/, "tmp", TheCall);
1849 Value *V2 = new CallInst(F, V, "tmp", TheCall);
1850 V2 = CastInst::createIntegerCast(V2, Type::Int32Ty, false/*ZExt*/,
1852 V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::Int32Ty, 1),
1854 Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, V,
1855 Constant::getNullValue(V->getType()), "tmp",
1857 V2 = new SelectInst(Cond, ConstantInt::get(Type::Int32Ty, 0), V2,
1858 TheCall->getName(), TheCall);
1859 TheCall->replaceAllUsesWith(V2);
1860 TheCall->eraseFromParent();
1865 /// This LibCallOptimization will simplify calls to the "ffsl" library
1866 /// calls. It simply uses FFSOptimization for which the transformation is
1868 /// @brief Simplify the ffsl library function.
1869 struct VISIBILITY_HIDDEN FFSLOptimization : public FFSOptimization {
1871 /// @brief Default Constructor
1872 FFSLOptimization() : FFSOptimization("ffsl",
1873 "Number of 'ffsl' calls simplified") {}
1877 /// This LibCallOptimization will simplify calls to the "ffsll" library
1878 /// calls. It simply uses FFSOptimization for which the transformation is
1880 /// @brief Simplify the ffsl library function.
1881 struct VISIBILITY_HIDDEN FFSLLOptimization : public FFSOptimization {
1883 /// @brief Default Constructor
1884 FFSLLOptimization() : FFSOptimization("ffsll",
1885 "Number of 'ffsll' calls simplified") {}
1889 /// This optimizes unary functions that take and return doubles.
1890 struct UnaryDoubleFPOptimizer : public LibCallOptimization {
1891 UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
1892 : LibCallOptimization(Fn, Desc) {}
1894 // Make sure that this function has the right prototype
1895 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1896 return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
1897 F->getReturnType() == Type::DoubleTy;
1900 /// ShrinkFunctionToFloatVersion - If the input to this function is really a
1901 /// float, strength reduce this to a float version of the function,
1902 /// e.g. floor((double)FLT) -> (double)floorf(FLT). This can only be called
1903 /// when the target supports the destination function and where there can be
1904 /// no precision loss.
1905 static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
1906 Constant *(SimplifyLibCalls::*FP)()){
1907 if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
1908 if (Cast->getOperand(0)->getType() == Type::FloatTy) {
1909 Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
1911 New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
1912 CI->replaceAllUsesWith(New);
1913 CI->eraseFromParent();
1914 if (Cast->use_empty())
1915 Cast->eraseFromParent();
1923 struct VISIBILITY_HIDDEN FloorOptimization : public UnaryDoubleFPOptimizer {
1925 : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
1927 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1929 // If this is a float argument passed in, convert to floorf.
1930 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
1933 return false; // opt failed
1937 struct VISIBILITY_HIDDEN CeilOptimization : public UnaryDoubleFPOptimizer {
1939 : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
1941 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1943 // If this is a float argument passed in, convert to ceilf.
1944 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
1947 return false; // opt failed
1951 struct VISIBILITY_HIDDEN RoundOptimization : public UnaryDoubleFPOptimizer {
1953 : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
1955 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1957 // If this is a float argument passed in, convert to roundf.
1958 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
1961 return false; // opt failed
1965 struct VISIBILITY_HIDDEN RintOptimization : public UnaryDoubleFPOptimizer {
1967 : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
1969 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1971 // If this is a float argument passed in, convert to rintf.
1972 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
1975 return false; // opt failed
1979 struct VISIBILITY_HIDDEN NearByIntOptimization : public UnaryDoubleFPOptimizer {
1980 NearByIntOptimization()
1981 : UnaryDoubleFPOptimizer("nearbyint",
1982 "Number of 'nearbyint' calls simplified") {}
1984 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1985 #ifdef HAVE_NEARBYINTF
1986 // If this is a float argument passed in, convert to nearbyintf.
1987 if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
1990 return false; // opt failed
1992 } NearByIntOptimizer;
1994 /// GetConstantStringInfo - This function computes the length of a
1995 /// null-terminated constant array of integers. This function can't rely on the
1996 /// size of the constant array because there could be a null terminator in the
1997 /// middle of the array.
1999 /// We also have to bail out if we find a non-integer constant initializer
2000 /// of one of the elements or if there is no null-terminator. The logic
2001 /// below checks each of these conditions and will return true only if all
2002 /// conditions are met. If the conditions aren't met, this returns false.
2004 /// If successful, the \p Array param is set to the constant array being
2005 /// indexed, the \p Length parameter is set to the length of the null-terminated
2006 /// string pointed to by V, the \p StartIdx value is set to the first
2007 /// element of the Array that V points to, and true is returned.
2008 static bool GetConstantStringInfo(Value *V, ConstantArray *&Array,
2009 uint64_t &Length, uint64_t &StartIdx) {
2010 assert(V != 0 && "Invalid args to GetConstantStringInfo");
2011 // Initialize results.
2017 // If the value is not a GEP instruction nor a constant expression with a
2018 // GEP instruction, then return false because ConstantArray can't occur
2020 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
2022 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
2023 if (CE->getOpcode() != Instruction::GetElementPtr)
2030 // Make sure the GEP has exactly three arguments.
2031 if (GEP->getNumOperands() != 3)
2034 // Check to make sure that the first operand of the GEP is an integer and
2035 // has value 0 so that we are sure we're indexing into the initializer.
2036 if (ConstantInt* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
2042 // If the second index isn't a ConstantInt, then this is a variable index
2043 // into the array. If this occurs, we can't say anything meaningful about
2046 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
2047 StartIdx = CI->getZExtValue();
2051 // The GEP instruction, constant or instruction, must reference a global
2052 // variable that is a constant and is initialized. The referenced constant
2053 // initializer is the array that we'll use for optimization.
2054 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
2055 if (!GV || !GV->isConstant() || !GV->hasInitializer())
2057 Constant *GlobalInit = GV->getInitializer();
2059 // Handle the ConstantAggregateZero case
2060 if (isa<ConstantAggregateZero>(GlobalInit)) {
2061 // This is a degenerate case. The initializer is constant zero so the
2062 // length of the string must be zero.
2067 // Must be a Constant Array
2068 Array = dyn_cast<ConstantArray>(GlobalInit);
2069 if (!Array) return false;
2071 // Get the number of elements in the array
2072 uint64_t NumElts = Array->getType()->getNumElements();
2074 // Traverse the constant array from start_idx (derived above) which is
2075 // the place the GEP refers to in the array.
2078 if (Length >= NumElts)
2079 return false; // The array isn't null terminated.
2081 Constant *Elt = Array->getOperand(Length);
2082 if (ConstantInt *CI = dyn_cast<ConstantInt>(Elt)) {
2083 // Check for the null terminator.
2085 break; // we found end of string
2087 return false; // This array isn't suitable, non-int initializer
2091 // Subtract out the initial value from the length
2093 return true; // success!
2096 /// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
2097 /// inserting the cast before IP, and return the cast.
2098 /// @brief Cast a value to a "C" string.
2099 static Value *CastToCStr(Value *V, Instruction &IP) {
2100 assert(isa<PointerType>(V->getType()) &&
2101 "Can't cast non-pointer type to C string type");
2102 const Type *SBPTy = PointerType::get(Type::Int8Ty);
2103 if (V->getType() != SBPTy)
2104 return new BitCastInst(V, SBPTy, V->getName(), &IP);
2109 // Additional cases that we need to add to this file:
2112 // * cbrt(expN(X)) -> expN(x/3)
2113 // * cbrt(sqrt(x)) -> pow(x,1/6)
2114 // * cbrt(sqrt(x)) -> pow(x,1/9)
2117 // * cos(-x) -> cos(x)
2120 // * exp(log(x)) -> x
2123 // * log(exp(x)) -> x
2124 // * log(x**y) -> y*log(x)
2125 // * log(exp(y)) -> y*log(e)
2126 // * log(exp2(y)) -> y*log(2)
2127 // * log(exp10(y)) -> y*log(10)
2128 // * log(sqrt(x)) -> 0.5*log(x)
2129 // * log(pow(x,y)) -> y*log(x)
2131 // lround, lroundf, lroundl:
2132 // * lround(cnst) -> cnst'
2135 // * memcmp(x,y,l) -> cnst
2136 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
2139 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
2140 // (if s is a global constant array)
2143 // * pow(exp(x),y) -> exp(x*y)
2144 // * pow(sqrt(x),y) -> pow(x,y*0.5)
2145 // * pow(pow(x,y),z)-> pow(x,y*z)
2148 // * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
2150 // round, roundf, roundl:
2151 // * round(cnst) -> cnst'
2154 // * signbit(cnst) -> cnst'
2155 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2157 // sqrt, sqrtf, sqrtl:
2158 // * sqrt(expN(x)) -> expN(x*0.5)
2159 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2160 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2163 // * stpcpy(str, "literal") ->
2164 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
2166 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
2167 // (if c is a constant integer and s is a constant string)
2168 // * strrchr(s1,0) -> strchr(s1,0)
2171 // * strncat(x,y,0) -> x
2172 // * strncat(x,y,0) -> x (if strlen(y) = 0)
2173 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
2176 // * strncpy(d,s,0) -> d
2177 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
2178 // (if s and l are constants)
2181 // * strpbrk(s,a) -> offset_in_for(s,a)
2182 // (if s and a are both constant strings)
2183 // * strpbrk(s,"") -> 0
2184 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
2187 // * strspn(s,a) -> const_int (if both args are constant)
2188 // * strspn("",a) -> 0
2189 // * strspn(s,"") -> 0
2190 // * strcspn(s,a) -> const_int (if both args are constant)
2191 // * strcspn("",a) -> 0
2192 // * strcspn(s,"") -> strlen(a)
2195 // * strstr(x,x) -> x
2196 // * strstr(s1,s2) -> offset_of_s2_in(s1)
2197 // (if s1 and s2 are constant strings)
2200 // * tan(atan(x)) -> x
2202 // trunc, truncf, truncl:
2203 // * trunc(cnst) -> cnst'