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 if (f->getReturnType() == PointerType::get(Type::Int8Ty) &&
542 /// @brief Perform the strchr optimizations
543 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
544 // If there aren't three operands, bail
545 if (ci->getNumOperands() != 3)
548 // Check that the first argument to strchr is a constant array of sbyte.
549 // If it is, get the length and data, otherwise return false.
550 uint64_t len, StartIdx;
551 ConstantArray* CA = 0;
552 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
555 // Check that the second argument to strchr is a constant int. If it isn't
556 // a constant integer, we can try an alternate optimization
557 ConstantInt* CSI = dyn_cast<ConstantInt>(ci->getOperand(2));
559 // The second operand is not constant just lower this to
560 // memchr since we know the length of the string since it is constant.
561 Constant *f = SLC.get_memchr();
565 ConstantInt::get(SLC.getIntPtrType(), len)
567 ci->replaceAllUsesWith(new CallInst(f, args, 3, ci->getName(), ci));
568 ci->eraseFromParent();
572 // Get the character we're looking for
573 int64_t chr = CSI->getSExtValue();
575 // Compute the offset
577 bool char_found = false;
578 for (uint64_t i = 0; i < len; ++i) {
579 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
580 // Check for the null terminator
582 break; // we found end of string
583 else if (CI->getSExtValue() == chr) {
591 // strchr(s,c) -> offset_of_in(c,s)
592 // (if c is a constant integer and s is a constant string)
594 Value* Idx = ConstantInt::get(Type::Int64Ty,offset);
595 GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1), Idx,
596 ci->getOperand(1)->getName()+".strchr",ci);
597 ci->replaceAllUsesWith(GEP);
599 ci->replaceAllUsesWith(
600 ConstantPointerNull::get(PointerType::get(Type::Int8Ty)));
602 ci->eraseFromParent();
607 /// This LibCallOptimization will simplify a call to the strcmp library
608 /// function. It optimizes out cases where one or both arguments are constant
609 /// and the result can be determined statically.
610 /// @brief Simplify the strcmp library function.
611 struct VISIBILITY_HIDDEN StrCmpOptimization : public LibCallOptimization {
613 StrCmpOptimization() : LibCallOptimization("strcmp",
614 "Number of 'strcmp' calls simplified") {}
616 /// @brief Make sure that the "strcmp" function has the right prototype
617 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
618 return F->getReturnType() == Type::Int32Ty && F->arg_size() == 2;
621 /// @brief Perform the strcmp optimization
622 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
623 // First, check to see if src and destination are the same. If they are,
624 // then the optimization is to replace the CallInst with a constant 0
625 // because the call is a no-op.
626 Value* s1 = ci->getOperand(1);
627 Value* s2 = ci->getOperand(2);
630 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
631 ci->eraseFromParent();
635 bool isstr_1 = false;
636 uint64_t len_1 = 0, StartIdx;
638 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
641 // strcmp("",x) -> *x
643 new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
645 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
646 ci->getName()+".int", ci);
647 ci->replaceAllUsesWith(cast);
648 ci->eraseFromParent();
653 bool isstr_2 = false;
656 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
659 // strcmp(x,"") -> *x
661 new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
663 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
664 ci->getName()+".int", ci);
665 ci->replaceAllUsesWith(cast);
666 ci->eraseFromParent();
671 if (isstr_1 && isstr_2) {
672 // strcmp(x,y) -> cnst (if both x and y are constant strings)
673 std::string str1 = A1->getAsString();
674 std::string str2 = A2->getAsString();
675 int result = strcmp(str1.c_str(), str2.c_str());
676 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
677 ci->eraseFromParent();
684 /// This LibCallOptimization will simplify a call to the strncmp library
685 /// function. It optimizes out cases where one or both arguments are constant
686 /// and the result can be determined statically.
687 /// @brief Simplify the strncmp library function.
688 struct VISIBILITY_HIDDEN StrNCmpOptimization : public LibCallOptimization {
690 StrNCmpOptimization() : LibCallOptimization("strncmp",
691 "Number of 'strncmp' calls simplified") {}
693 /// @brief Make sure that the "strncmp" function has the right prototype
694 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
695 if (f->getReturnType() == Type::Int32Ty && f->arg_size() == 3)
700 /// @brief Perform the strncpy optimization
701 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
702 // First, check to see if src and destination are the same. If they are,
703 // then the optimization is to replace the CallInst with a constant 0
704 // because the call is a no-op.
705 Value* s1 = ci->getOperand(1);
706 Value* s2 = ci->getOperand(2);
708 // strncmp(x,x,l) -> 0
709 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
710 ci->eraseFromParent();
714 // Check the length argument, if it is Constant zero then the strings are
716 uint64_t len_arg = 0;
717 bool len_arg_is_const = false;
718 if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
719 len_arg_is_const = true;
720 len_arg = len_CI->getZExtValue();
722 // strncmp(x,y,0) -> 0
723 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
724 ci->eraseFromParent();
729 bool isstr_1 = false;
730 uint64_t len_1 = 0, StartIdx;
732 if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
735 // strncmp("",x) -> *x
736 LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
738 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
739 ci->getName()+".int", ci);
740 ci->replaceAllUsesWith(cast);
741 ci->eraseFromParent();
746 bool isstr_2 = false;
749 if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
752 // strncmp(x,"") -> *x
753 LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
755 CastInst::create(Instruction::SExt, load, Type::Int32Ty,
756 ci->getName()+".int", ci);
757 ci->replaceAllUsesWith(cast);
758 ci->eraseFromParent();
763 if (isstr_1 && isstr_2 && len_arg_is_const) {
764 // strncmp(x,y,const) -> constant
765 std::string str1 = A1->getAsString();
766 std::string str2 = A2->getAsString();
767 int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
768 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
769 ci->eraseFromParent();
776 /// This LibCallOptimization will simplify a call to the strcpy library
777 /// function. Two optimizations are possible:
778 /// (1) If src and dest are the same and not volatile, just return dest
779 /// (2) If the src is a constant then we can convert to llvm.memmove
780 /// @brief Simplify the strcpy library function.
781 struct VISIBILITY_HIDDEN StrCpyOptimization : public LibCallOptimization {
783 StrCpyOptimization() : LibCallOptimization("strcpy",
784 "Number of 'strcpy' calls simplified") {}
786 /// @brief Make sure that the "strcpy" function has the right prototype
787 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
788 if (f->getReturnType() == PointerType::get(Type::Int8Ty))
789 if (f->arg_size() == 2) {
790 Function::const_arg_iterator AI = f->arg_begin();
791 if (AI++->getType() == PointerType::get(Type::Int8Ty))
792 if (AI->getType() == PointerType::get(Type::Int8Ty)) {
793 // Indicate this is a suitable call type.
800 /// @brief Perform the strcpy optimization
801 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
802 // First, check to see if src and destination are the same. If they are,
803 // then the optimization is to replace the CallInst with the destination
804 // because the call is a no-op. Note that this corresponds to the
805 // degenerate strcpy(X,X) case which should have "undefined" results
806 // according to the C specification. However, it occurs sometimes and
807 // we optimize it as a no-op.
808 Value* dest = ci->getOperand(1);
809 Value* src = ci->getOperand(2);
811 ci->replaceAllUsesWith(dest);
812 ci->eraseFromParent();
816 // Get the length of the constant string referenced by the second operand,
817 // the "src" parameter. Fail the optimization if we can't get the length
818 // (note that GetConstantStringInfo does lots of checks to make sure this
820 uint64_t len, StartIdx;
822 if (!GetConstantStringInfo(ci->getOperand(2), A, len, StartIdx))
825 // If the constant string's length is zero we can optimize this by just
826 // doing a store of 0 at the first byte of the destination
828 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
829 ci->replaceAllUsesWith(dest);
830 ci->eraseFromParent();
834 // Increment the length because we actually want to memcpy the null
835 // terminator as well.
838 // We have enough information to now generate the memcpy call to
839 // do the concatenation for us.
842 ConstantInt::get(SLC.getIntPtrType(),len), // length
843 ConstantInt::get(Type::Int32Ty, 1) // alignment
845 new CallInst(SLC.get_memcpy(), vals, 4, "", ci);
847 // Finally, substitute the first operand of the strcat call for the
848 // strcat call itself since strcat returns its first operand; and,
849 // kill the strcat CallInst.
850 ci->replaceAllUsesWith(dest);
851 ci->eraseFromParent();
856 /// This LibCallOptimization will simplify a call to the strlen library
857 /// function by replacing it with a constant value if the string provided to
858 /// it is a constant array.
859 /// @brief Simplify the strlen library function.
860 struct VISIBILITY_HIDDEN StrLenOptimization : public LibCallOptimization {
861 StrLenOptimization() : LibCallOptimization("strlen",
862 "Number of 'strlen' calls simplified") {}
864 /// @brief Make sure that the "strlen" function has the right prototype
865 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
867 if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
868 if (f->arg_size() == 1)
869 if (Function::const_arg_iterator AI = f->arg_begin())
870 if (AI->getType() == PointerType::get(Type::Int8Ty))
875 /// @brief Perform the strlen optimization
876 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
878 // Make sure we're dealing with an sbyte* here.
879 Value* str = ci->getOperand(1);
880 if (str->getType() != PointerType::get(Type::Int8Ty))
883 // Does the call to strlen have exactly one use?
885 // Is that single use a icmp operator?
886 if (ICmpInst* bop = dyn_cast<ICmpInst>(ci->use_back()))
887 // Is it compared against a constant integer?
888 if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
890 // Get the value the strlen result is compared to
891 uint64_t val = CI->getZExtValue();
893 // If its compared against length 0 with == or !=
895 (bop->getPredicate() == ICmpInst::ICMP_EQ ||
896 bop->getPredicate() == ICmpInst::ICMP_NE))
898 // strlen(x) != 0 -> *x != 0
899 // strlen(x) == 0 -> *x == 0
900 LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
901 ICmpInst* rbop = new ICmpInst(bop->getPredicate(), load,
902 ConstantInt::get(Type::Int8Ty,0),
903 bop->getName()+".strlen", ci);
904 bop->replaceAllUsesWith(rbop);
905 bop->eraseFromParent();
906 ci->eraseFromParent();
911 // Get the length of the constant string operand
912 uint64_t len = 0, StartIdx;
914 if (!GetConstantStringInfo(ci->getOperand(1), A, len, StartIdx))
917 // strlen("xyz") -> 3 (for example)
918 const Type *Ty = SLC.getTargetData()->getIntPtrType();
919 ci->replaceAllUsesWith(ConstantInt::get(Ty, len));
921 ci->eraseFromParent();
926 /// IsOnlyUsedInEqualsComparison - Return true if it only matters that the value
927 /// is equal or not-equal to zero.
928 static bool IsOnlyUsedInEqualsZeroComparison(Instruction *I) {
929 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
931 Instruction *User = cast<Instruction>(*UI);
932 if (ICmpInst *IC = dyn_cast<ICmpInst>(User)) {
933 if ((IC->getPredicate() == ICmpInst::ICMP_NE ||
934 IC->getPredicate() == ICmpInst::ICMP_EQ) &&
935 isa<Constant>(IC->getOperand(1)) &&
936 cast<Constant>(IC->getOperand(1))->isNullValue())
938 } else if (CastInst *CI = dyn_cast<CastInst>(User))
939 if (CI->getType() == Type::Int1Ty)
941 // Unknown instruction.
947 /// This memcmpOptimization will simplify a call to the memcmp library
949 struct VISIBILITY_HIDDEN memcmpOptimization : public LibCallOptimization {
950 /// @brief Default Constructor
952 : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
954 /// @brief Make sure that the "memcmp" function has the right prototype
955 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
956 Function::const_arg_iterator AI = F->arg_begin();
957 if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
958 if (!isa<PointerType>((++AI)->getType())) return false;
959 if (!(++AI)->getType()->isInteger()) return false;
960 if (!F->getReturnType()->isInteger()) return false;
964 /// Because of alignment and instruction information that we don't have, we
965 /// leave the bulk of this to the code generators.
967 /// Note that we could do much more if we could force alignment on otherwise
968 /// small aligned allocas, or if we could indicate that loads have a small
970 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
971 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
973 // If the two operands are the same, return zero.
975 // memcmp(s,s,x) -> 0
976 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
977 CI->eraseFromParent();
981 // Make sure we have a constant length.
982 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
983 if (!LenC) return false;
984 uint64_t Len = LenC->getZExtValue();
986 // If the length is zero, this returns 0.
989 // memcmp(s1,s2,0) -> 0
990 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
991 CI->eraseFromParent();
994 // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
995 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
996 CastInst *Op1Cast = CastInst::create(
997 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
998 CastInst *Op2Cast = CastInst::create(
999 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1000 Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
1001 Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
1002 Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
1003 if (RV->getType() != CI->getType())
1004 RV = CastInst::createIntegerCast(RV, CI->getType(), false,
1006 CI->replaceAllUsesWith(RV);
1007 CI->eraseFromParent();
1011 if (IsOnlyUsedInEqualsZeroComparison(CI)) {
1012 // TODO: IF both are aligned, use a short load/compare.
1014 // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
1015 const Type *UCharPtr = PointerType::get(Type::Int8Ty);
1016 CastInst *Op1Cast = CastInst::create(
1017 Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
1018 CastInst *Op2Cast = CastInst::create(
1019 Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
1020 Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
1021 Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
1022 Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
1023 CI->getName()+".d1", CI);
1024 Constant *One = ConstantInt::get(Type::Int32Ty, 1);
1025 Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
1026 Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
1027 Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
1028 Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
1029 Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
1030 CI->getName()+".d1", CI);
1031 Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
1032 if (Or->getType() != CI->getType())
1033 Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/,
1035 CI->replaceAllUsesWith(Or);
1036 CI->eraseFromParent();
1049 /// This LibCallOptimization will simplify a call to the memcpy library
1050 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1051 /// bytes depending on the length of the string and the alignment. Additional
1052 /// optimizations are possible in code generation (sequence of immediate store)
1053 /// @brief Simplify the memcpy library function.
1054 struct VISIBILITY_HIDDEN LLVMMemCpyMoveOptzn : public LibCallOptimization {
1055 LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
1056 : LibCallOptimization(fname, desc) {}
1058 /// @brief Make sure that the "memcpy" function has the right prototype
1059 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
1060 // Just make sure this has 4 arguments per LLVM spec.
1061 return (f->arg_size() == 4);
1064 /// Because of alignment and instruction information that we don't have, we
1065 /// leave the bulk of this to the code generators. The optimization here just
1066 /// deals with a few degenerate cases where the length of the string and the
1067 /// alignment match the sizes of our intrinsic types so we can do a load and
1068 /// store instead of the memcpy call.
1069 /// @brief Perform the memcpy optimization.
1070 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
1071 // Make sure we have constant int values to work with
1072 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1075 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1079 // If the length is larger than the alignment, we can't optimize
1080 uint64_t len = LEN->getZExtValue();
1081 uint64_t alignment = ALIGN->getZExtValue();
1083 alignment = 1; // Alignment 0 is identity for alignment 1
1084 if (len > alignment)
1087 // Get the type we will cast to, based on size of the string
1088 Value* dest = ci->getOperand(1);
1089 Value* src = ci->getOperand(2);
1090 const Type* castType = 0;
1094 // memcpy(d,s,0,a) -> noop
1095 ci->eraseFromParent();
1097 case 1: castType = Type::Int8Ty; break;
1098 case 2: castType = Type::Int16Ty; break;
1099 case 4: castType = Type::Int32Ty; break;
1100 case 8: castType = Type::Int64Ty; break;
1105 // Cast source and dest to the right sized primitive and then load/store
1106 CastInst* SrcCast = CastInst::create(Instruction::BitCast,
1107 src, PointerType::get(castType), src->getName()+".cast", ci);
1108 CastInst* DestCast = CastInst::create(Instruction::BitCast,
1109 dest, PointerType::get(castType),dest->getName()+".cast", ci);
1110 LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
1111 new StoreInst(LI, DestCast, ci);
1112 ci->eraseFromParent();
1117 /// This LibCallOptimization will simplify a call to the memcpy/memmove library
1119 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
1120 "Number of 'llvm.memcpy' calls simplified");
1121 LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
1122 "Number of 'llvm.memcpy' calls simplified");
1123 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
1124 "Number of 'llvm.memmove' calls simplified");
1125 LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
1126 "Number of 'llvm.memmove' calls simplified");
1128 /// This LibCallOptimization will simplify a call to the memset library
1129 /// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
1130 /// bytes depending on the length argument.
1131 struct VISIBILITY_HIDDEN LLVMMemSetOptimization : public LibCallOptimization {
1132 /// @brief Default Constructor
1133 LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
1134 "Number of 'llvm.memset' calls simplified") {}
1136 /// @brief Make sure that the "memset" function has the right prototype
1137 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
1138 // Just make sure this has 3 arguments per LLVM spec.
1139 return F->arg_size() == 4;
1142 /// Because of alignment and instruction information that we don't have, we
1143 /// leave the bulk of this to the code generators. The optimization here just
1144 /// deals with a few degenerate cases where the length parameter is constant
1145 /// and the alignment matches the sizes of our intrinsic types so we can do
1146 /// store instead of the memcpy call. Other calls are transformed into the
1147 /// llvm.memset intrinsic.
1148 /// @brief Perform the memset optimization.
1149 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
1150 // Make sure we have constant int values to work with
1151 ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
1154 ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
1158 // Extract the length and alignment
1159 uint64_t len = LEN->getZExtValue();
1160 uint64_t alignment = ALIGN->getZExtValue();
1162 // Alignment 0 is identity for alignment 1
1166 // If the length is zero, this is a no-op
1168 // memset(d,c,0,a) -> noop
1169 ci->eraseFromParent();
1173 // If the length is larger than the alignment, we can't optimize
1174 if (len > alignment)
1177 // Make sure we have a constant ubyte to work with so we can extract
1178 // the value to be filled.
1179 ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
1182 if (FILL->getType() != Type::Int8Ty)
1185 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
1187 // Extract the fill character
1188 uint64_t fill_char = FILL->getZExtValue();
1189 uint64_t fill_value = fill_char;
1191 // Get the type we will cast to, based on size of memory area to fill, and
1192 // and the value we will store there.
1193 Value* dest = ci->getOperand(1);
1194 const Type* castType = 0;
1197 castType = Type::Int8Ty;
1200 castType = Type::Int16Ty;
1201 fill_value |= fill_char << 8;
1204 castType = Type::Int32Ty;
1205 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1208 castType = Type::Int64Ty;
1209 fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
1210 fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
1211 fill_value |= fill_char << 56;
1217 // Cast dest to the right sized primitive and then load/store
1218 CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType),
1219 dest->getName()+".cast", ci);
1220 new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
1221 ci->eraseFromParent();
1226 LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
1227 LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
1230 /// This LibCallOptimization will simplify calls to the "pow" library
1231 /// function. It looks for cases where the result of pow is well known and
1232 /// substitutes the appropriate value.
1233 /// @brief Simplify the pow library function.
1234 struct VISIBILITY_HIDDEN PowOptimization : public LibCallOptimization {
1236 /// @brief Default Constructor
1237 PowOptimization() : LibCallOptimization("pow",
1238 "Number of 'pow' calls simplified") {}
1240 /// @brief Make sure that the "pow" function has the right prototype
1241 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1242 // Just make sure this has 2 arguments
1243 return (f->arg_size() == 2);
1246 /// @brief Perform the pow optimization.
1247 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1248 const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
1249 Value* base = ci->getOperand(1);
1250 Value* expn = ci->getOperand(2);
1251 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
1252 double Op1V = Op1->getValue();
1254 // pow(1.0,x) -> 1.0
1255 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1256 ci->eraseFromParent();
1259 } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
1260 double Op2V = Op2->getValue();
1262 // pow(x,0.0) -> 1.0
1263 ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
1264 ci->eraseFromParent();
1266 } else if (Op2V == 0.5) {
1267 // pow(x,0.5) -> sqrt(x)
1268 CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
1269 ci->getName()+".pow",ci);
1270 ci->replaceAllUsesWith(sqrt_inst);
1271 ci->eraseFromParent();
1273 } else if (Op2V == 1.0) {
1275 ci->replaceAllUsesWith(base);
1276 ci->eraseFromParent();
1278 } else if (Op2V == -1.0) {
1279 // pow(x,-1.0) -> 1.0/x
1280 BinaryOperator* div_inst= BinaryOperator::createFDiv(
1281 ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
1282 ci->replaceAllUsesWith(div_inst);
1283 ci->eraseFromParent();
1287 return false; // opt failed
1291 /// This LibCallOptimization will simplify calls to the "printf" library
1292 /// function. It looks for cases where the result of printf is not used and the
1293 /// operation can be reduced to something simpler.
1294 /// @brief Simplify the printf library function.
1295 struct VISIBILITY_HIDDEN PrintfOptimization : public LibCallOptimization {
1297 /// @brief Default Constructor
1298 PrintfOptimization() : LibCallOptimization("printf",
1299 "Number of 'printf' calls simplified") {}
1301 /// @brief Make sure that the "printf" function has the right prototype
1302 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1303 // Just make sure this has at least 1 arguments
1304 return (f->arg_size() >= 1);
1307 /// @brief Perform the printf optimization.
1308 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1309 // If the call has more than 2 operands, we can't optimize it
1310 if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
1313 // If the result of the printf call is used, none of these optimizations
1315 if (!ci->use_empty())
1318 // All the optimizations depend on the length of the first argument and the
1319 // fact that it is a constant string array. Check that now
1320 uint64_t len, StartIdx;
1321 ConstantArray* CA = 0;
1322 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1325 if (len != 2 && len != 3)
1328 // The first character has to be a %
1329 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1330 if (CI->getZExtValue() != '%')
1333 // Get the second character and switch on its value
1334 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1335 switch (CI->getZExtValue()) {
1339 dyn_cast<ConstantInt>(CA->getOperand(2))->getZExtValue() != '\n')
1342 // printf("%s\n",str) -> puts(str)
1343 std::vector<Value*> args;
1344 new CallInst(SLC.get_puts(), CastToCStr(ci->getOperand(2), *ci),
1346 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1351 // printf("%c",c) -> putchar(c)
1355 CastInst *Char = CastInst::createSExtOrBitCast(
1356 ci->getOperand(2), Type::Int32Ty, CI->getName()+".int", ci);
1357 new CallInst(SLC.get_putchar(), Char, "", ci);
1358 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, 1));
1364 ci->eraseFromParent();
1369 /// This LibCallOptimization will simplify calls to the "fprintf" library
1370 /// function. It looks for cases where the result of fprintf is not used and the
1371 /// operation can be reduced to something simpler.
1372 /// @brief Simplify the fprintf library function.
1373 struct VISIBILITY_HIDDEN FPrintFOptimization : public LibCallOptimization {
1375 /// @brief Default Constructor
1376 FPrintFOptimization() : LibCallOptimization("fprintf",
1377 "Number of 'fprintf' calls simplified") {}
1379 /// @brief Make sure that the "fprintf" function has the right prototype
1380 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1381 // Just make sure this has at least 2 arguments
1382 return (f->arg_size() >= 2);
1385 /// @brief Perform the fprintf optimization.
1386 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1387 // If the call has more than 3 operands, we can't optimize it
1388 if (ci->getNumOperands() > 4 || ci->getNumOperands() <= 2)
1391 // If the result of the fprintf call is used, none of these optimizations
1393 if (!ci->use_empty())
1396 // All the optimizations depend on the length of the second argument and the
1397 // fact that it is a constant string array. Check that now
1398 uint64_t len, StartIdx;
1399 ConstantArray* CA = 0;
1400 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1403 if (ci->getNumOperands() == 3) {
1404 // Make sure there's no % in the constant array
1405 for (unsigned i = 0; i < len; ++i) {
1406 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1407 // Check for the null terminator
1408 if (CI->getZExtValue() == '%')
1409 return false; // we found end of string
1415 // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
1416 const Type* FILEptr_type = ci->getOperand(1)->getType();
1418 // Make sure that the fprintf() and fwrite() functions both take the
1419 // same type of char pointer.
1420 if (ci->getOperand(2)->getType() != PointerType::get(Type::Int8Ty))
1425 ConstantInt::get(SLC.getIntPtrType(),len),
1426 ConstantInt::get(SLC.getIntPtrType(),1),
1429 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4, ci->getName(), ci);
1430 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1431 ci->eraseFromParent();
1435 // The remaining optimizations require the format string to be length 2
1440 // The first character has to be a %
1441 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1442 if (CI->getZExtValue() != '%')
1445 // Get the second character and switch on its value
1446 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1447 switch (CI->getZExtValue()) {
1450 uint64_t len, StartIdx;
1451 ConstantArray* CA = 0;
1452 if (GetConstantStringInfo(ci->getOperand(3), CA, len, StartIdx)) {
1453 // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
1454 const Type* FILEptr_type = ci->getOperand(1)->getType();
1456 CastToCStr(ci->getOperand(3), *ci),
1457 ConstantInt::get(SLC.getIntPtrType(), len),
1458 ConstantInt::get(SLC.getIntPtrType(), 1),
1461 new CallInst(SLC.get_fwrite(FILEptr_type), args, 4,ci->getName(), ci);
1462 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, len));
1464 // fprintf(file,"%s",str) -> fputs(str,file)
1465 const Type* FILEptr_type = ci->getOperand(1)->getType();
1466 new CallInst(SLC.get_fputs(FILEptr_type),
1467 CastToCStr(ci->getOperand(3), *ci),
1468 ci->getOperand(1), ci->getName(),ci);
1469 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1475 // fprintf(file,"%c",c) -> fputc(c,file)
1476 const Type* FILEptr_type = ci->getOperand(1)->getType();
1477 CastInst* cast = CastInst::createSExtOrBitCast(
1478 ci->getOperand(3), Type::Int32Ty, CI->getName()+".int", ci);
1479 new CallInst(SLC.get_fputc(FILEptr_type), cast,ci->getOperand(1),"",ci);
1480 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1486 ci->eraseFromParent();
1491 /// This LibCallOptimization will simplify calls to the "sprintf" library
1492 /// function. It looks for cases where the result of sprintf is not used and the
1493 /// operation can be reduced to something simpler.
1494 /// @brief Simplify the sprintf library function.
1495 struct VISIBILITY_HIDDEN SPrintFOptimization : public LibCallOptimization {
1497 /// @brief Default Constructor
1498 SPrintFOptimization() : LibCallOptimization("sprintf",
1499 "Number of 'sprintf' calls simplified") {}
1501 /// @brief Make sure that the "fprintf" function has the right prototype
1502 virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
1503 // Just make sure this has at least 2 arguments
1504 return (f->getReturnType() == Type::Int32Ty && f->arg_size() >= 2);
1507 /// @brief Perform the sprintf optimization.
1508 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1509 // If the call has more than 3 operands, we can't optimize it
1510 if (ci->getNumOperands() > 4 || ci->getNumOperands() < 3)
1513 // All the optimizations depend on the length of the second argument and the
1514 // fact that it is a constant string array. Check that now
1515 uint64_t len, StartIdx;
1516 ConstantArray* CA = 0;
1517 if (!GetConstantStringInfo(ci->getOperand(2), CA, len, StartIdx))
1520 if (ci->getNumOperands() == 3) {
1522 // If the length is 0, we just need to store a null byte
1523 new StoreInst(ConstantInt::get(Type::Int8Ty,0),ci->getOperand(1),ci);
1524 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1525 ci->eraseFromParent();
1529 // Make sure there's no % in the constant array
1530 for (unsigned i = 0; i < len; ++i) {
1531 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
1532 // Check for the null terminator
1533 if (CI->getZExtValue() == '%')
1534 return false; // we found a %, can't optimize
1536 return false; // initializer is not constant int, can't optimize
1540 // Increment length because we want to copy the null byte too
1543 // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
1547 ConstantInt::get(SLC.getIntPtrType(),len),
1548 ConstantInt::get(Type::Int32Ty, 1)
1550 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1551 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,len));
1552 ci->eraseFromParent();
1556 // The remaining optimizations require the format string to be length 2
1561 // The first character has to be a %
1562 if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
1563 if (CI->getZExtValue() != '%')
1566 // Get the second character and switch on its value
1567 ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
1568 switch (CI->getZExtValue()) {
1570 // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1571 Value *Len = new CallInst(SLC.get_strlen(),
1572 CastToCStr(ci->getOperand(3), *ci),
1573 ci->getOperand(3)->getName()+".len", ci);
1574 Value *Len1 = BinaryOperator::createAdd(Len,
1575 ConstantInt::get(Len->getType(), 1),
1576 Len->getName()+"1", ci);
1577 if (Len1->getType() != SLC.getIntPtrType())
1578 Len1 = CastInst::createIntegerCast(Len1, SLC.getIntPtrType(), false,
1579 Len1->getName(), ci);
1581 CastToCStr(ci->getOperand(1), *ci),
1582 CastToCStr(ci->getOperand(3), *ci),
1584 ConstantInt::get(Type::Int32Ty,1)
1586 new CallInst(SLC.get_memcpy(), args, 4, "", ci);
1588 // The strlen result is the unincremented number of bytes in the string.
1589 if (!ci->use_empty()) {
1590 if (Len->getType() != ci->getType())
1591 Len = CastInst::createIntegerCast(Len, ci->getType(), false,
1592 Len->getName(), ci);
1593 ci->replaceAllUsesWith(Len);
1595 ci->eraseFromParent();
1599 // sprintf(dest,"%c",chr) -> store chr, dest
1600 CastInst* cast = CastInst::createTruncOrBitCast(
1601 ci->getOperand(3), Type::Int8Ty, "char", ci);
1602 new StoreInst(cast, ci->getOperand(1), ci);
1603 GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
1604 ConstantInt::get(Type::Int32Ty,1),ci->getOperand(1)->getName()+".end",
1606 new StoreInst(ConstantInt::get(Type::Int8Ty,0),gep,ci);
1607 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1608 ci->eraseFromParent();
1616 /// This LibCallOptimization will simplify calls to the "fputs" library
1617 /// function. It looks for cases where the result of fputs is not used and the
1618 /// operation can be reduced to something simpler.
1619 /// @brief Simplify the puts library function.
1620 struct VISIBILITY_HIDDEN PutsOptimization : public LibCallOptimization {
1622 /// @brief Default Constructor
1623 PutsOptimization() : LibCallOptimization("fputs",
1624 "Number of 'fputs' calls simplified") {}
1626 /// @brief Make sure that the "fputs" function has the right prototype
1627 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1628 // Just make sure this has 2 arguments
1629 return F->arg_size() == 2;
1632 /// @brief Perform the fputs optimization.
1633 virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
1634 // If the result is used, none of these optimizations work
1635 if (!ci->use_empty())
1638 // All the optimizations depend on the length of the first argument and the
1639 // fact that it is a constant string array. Check that now
1640 uint64_t len, StartIdx;
1642 if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx))
1647 // fputs("",F) -> noop
1651 // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
1652 const Type* FILEptr_type = ci->getOperand(2)->getType();
1653 LoadInst* loadi = new LoadInst(ci->getOperand(1),
1654 ci->getOperand(1)->getName()+".byte",ci);
1655 CastInst* casti = new SExtInst(loadi, Type::Int32Ty,
1656 loadi->getName()+".int", ci);
1657 new CallInst(SLC.get_fputc(FILEptr_type), casti,
1658 ci->getOperand(2), "", ci);
1663 // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
1664 const Type* FILEptr_type = ci->getOperand(2)->getType();
1667 ConstantInt::get(SLC.getIntPtrType(),len),
1668 ConstantInt::get(SLC.getIntPtrType(),1),
1671 new CallInst(SLC.get_fwrite(FILEptr_type), parms, 4, "", ci);
1675 ci->eraseFromParent();
1676 return true; // success
1680 /// This LibCallOptimization will simplify calls to the "isdigit" library
1681 /// function. It simply does range checks the parameter explicitly.
1682 /// @brief Simplify the isdigit library function.
1683 struct VISIBILITY_HIDDEN isdigitOptimization : public LibCallOptimization {
1685 isdigitOptimization() : LibCallOptimization("isdigit",
1686 "Number of 'isdigit' calls simplified") {}
1688 /// @brief Make sure that the "isdigit" function has the right prototype
1689 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1690 // Just make sure this has 1 argument
1691 return (f->arg_size() == 1);
1694 /// @brief Perform the toascii optimization.
1695 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1696 if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
1697 // isdigit(c) -> 0 or 1, if 'c' is constant
1698 uint64_t val = CI->getZExtValue();
1699 if (val >= '0' && val <='9')
1700 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,1));
1702 ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
1703 ci->eraseFromParent();
1707 // isdigit(c) -> (unsigned)c - '0' <= 9
1708 CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
1709 Type::Int32Ty, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
1710 BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
1711 ConstantInt::get(Type::Int32Ty,0x30),
1712 ci->getOperand(1)->getName()+".sub",ci);
1713 ICmpInst* setcond_inst = new ICmpInst(ICmpInst::ICMP_ULE,sub_inst,
1714 ConstantInt::get(Type::Int32Ty,9),
1715 ci->getOperand(1)->getName()+".cmp",ci);
1716 CastInst* c2 = new ZExtInst(setcond_inst, Type::Int32Ty,
1717 ci->getOperand(1)->getName()+".isdigit", ci);
1718 ci->replaceAllUsesWith(c2);
1719 ci->eraseFromParent();
1724 struct VISIBILITY_HIDDEN isasciiOptimization : public LibCallOptimization {
1726 isasciiOptimization()
1727 : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
1729 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1730 return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() &&
1731 F->getReturnType()->isInteger();
1734 /// @brief Perform the isascii optimization.
1735 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1736 // isascii(c) -> (unsigned)c < 128
1737 Value *V = CI->getOperand(1);
1738 Value *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, V,
1739 ConstantInt::get(V->getType(), 128),
1740 V->getName()+".isascii", CI);
1741 if (Cmp->getType() != CI->getType())
1742 Cmp = new BitCastInst(Cmp, CI->getType(), Cmp->getName(), CI);
1743 CI->replaceAllUsesWith(Cmp);
1744 CI->eraseFromParent();
1750 /// This LibCallOptimization will simplify calls to the "toascii" library
1751 /// function. It simply does the corresponding and operation to restrict the
1752 /// range of values to the ASCII character set (0-127).
1753 /// @brief Simplify the toascii library function.
1754 struct VISIBILITY_HIDDEN ToAsciiOptimization : public LibCallOptimization {
1756 /// @brief Default Constructor
1757 ToAsciiOptimization() : LibCallOptimization("toascii",
1758 "Number of 'toascii' calls simplified") {}
1760 /// @brief Make sure that the "fputs" function has the right prototype
1761 virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
1762 // Just make sure this has 2 arguments
1763 return (f->arg_size() == 1);
1766 /// @brief Perform the toascii optimization.
1767 virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
1768 // toascii(c) -> (c & 0x7f)
1769 Value* chr = ci->getOperand(1);
1770 BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
1771 ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
1772 ci->replaceAllUsesWith(and_inst);
1773 ci->eraseFromParent();
1778 /// This LibCallOptimization will simplify calls to the "ffs" library
1779 /// calls which find the first set bit in an int, long, or long long. The
1780 /// optimization is to compute the result at compile time if the argument is
1782 /// @brief Simplify the ffs library function.
1783 struct VISIBILITY_HIDDEN FFSOptimization : public LibCallOptimization {
1785 /// @brief Subclass Constructor
1786 FFSOptimization(const char* funcName, const char* description)
1787 : LibCallOptimization(funcName, description) {}
1790 /// @brief Default Constructor
1791 FFSOptimization() : LibCallOptimization("ffs",
1792 "Number of 'ffs' calls simplified") {}
1794 /// @brief Make sure that the "ffs" function has the right prototype
1795 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1796 // Just make sure this has 2 arguments
1797 return F->arg_size() == 1 && F->getReturnType() == Type::Int32Ty;
1800 /// @brief Perform the ffs optimization.
1801 virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
1802 if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
1803 // ffs(cnst) -> bit#
1804 // ffsl(cnst) -> bit#
1805 // ffsll(cnst) -> bit#
1806 uint64_t val = CI->getZExtValue();
1810 while ((val & 1) == 0) {
1815 TheCall->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty, result));
1816 TheCall->eraseFromParent();
1820 // ffs(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1821 // ffsl(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1822 // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
1823 const Type *ArgType = TheCall->getOperand(1)->getType();
1824 const char *CTTZName;
1825 assert(ArgType->getTypeID() == Type::IntegerTyID &&
1826 "llvm.cttz argument is not an integer?");
1827 unsigned BitWidth = cast<IntegerType>(ArgType)->getBitWidth();
1829 CTTZName = "llvm.cttz.i8";
1830 else if (BitWidth == 16)
1831 CTTZName = "llvm.cttz.i16";
1832 else if (BitWidth == 32)
1833 CTTZName = "llvm.cttz.i32";
1835 assert(BitWidth == 64 && "Unknown bitwidth");
1836 CTTZName = "llvm.cttz.i64";
1839 Constant *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
1841 Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType,
1842 false/*ZExt*/, "tmp", TheCall);
1843 Value *V2 = new CallInst(F, V, "tmp", TheCall);
1844 V2 = CastInst::createIntegerCast(V2, Type::Int32Ty, false/*ZExt*/,
1846 V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::Int32Ty, 1),
1848 Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, V,
1849 Constant::getNullValue(V->getType()), "tmp",
1851 V2 = new SelectInst(Cond, ConstantInt::get(Type::Int32Ty, 0), V2,
1852 TheCall->getName(), TheCall);
1853 TheCall->replaceAllUsesWith(V2);
1854 TheCall->eraseFromParent();
1859 /// This LibCallOptimization will simplify calls to the "ffsl" library
1860 /// calls. It simply uses FFSOptimization for which the transformation is
1862 /// @brief Simplify the ffsl library function.
1863 struct VISIBILITY_HIDDEN FFSLOptimization : public FFSOptimization {
1865 /// @brief Default Constructor
1866 FFSLOptimization() : FFSOptimization("ffsl",
1867 "Number of 'ffsl' calls simplified") {}
1871 /// This LibCallOptimization will simplify calls to the "ffsll" library
1872 /// calls. It simply uses FFSOptimization for which the transformation is
1874 /// @brief Simplify the ffsl library function.
1875 struct VISIBILITY_HIDDEN FFSLLOptimization : public FFSOptimization {
1877 /// @brief Default Constructor
1878 FFSLLOptimization() : FFSOptimization("ffsll",
1879 "Number of 'ffsll' calls simplified") {}
1883 /// This optimizes unary functions that take and return doubles.
1884 struct UnaryDoubleFPOptimizer : public LibCallOptimization {
1885 UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
1886 : LibCallOptimization(Fn, Desc) {}
1888 // Make sure that this function has the right prototype
1889 virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
1890 return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
1891 F->getReturnType() == Type::DoubleTy;
1894 /// ShrinkFunctionToFloatVersion - If the input to this function is really a
1895 /// float, strength reduce this to a float version of the function,
1896 /// e.g. floor((double)FLT) -> (double)floorf(FLT). This can only be called
1897 /// when the target supports the destination function and where there can be
1898 /// no precision loss.
1899 static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
1900 Constant *(SimplifyLibCalls::*FP)()){
1901 if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
1902 if (Cast->getOperand(0)->getType() == Type::FloatTy) {
1903 Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
1905 New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
1906 CI->replaceAllUsesWith(New);
1907 CI->eraseFromParent();
1908 if (Cast->use_empty())
1909 Cast->eraseFromParent();
1917 struct VISIBILITY_HIDDEN FloorOptimization : public UnaryDoubleFPOptimizer {
1919 : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
1921 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1923 // If this is a float argument passed in, convert to floorf.
1924 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
1927 return false; // opt failed
1931 struct VISIBILITY_HIDDEN CeilOptimization : public UnaryDoubleFPOptimizer {
1933 : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
1935 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1937 // If this is a float argument passed in, convert to ceilf.
1938 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
1941 return false; // opt failed
1945 struct VISIBILITY_HIDDEN RoundOptimization : public UnaryDoubleFPOptimizer {
1947 : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
1949 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1951 // If this is a float argument passed in, convert to roundf.
1952 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
1955 return false; // opt failed
1959 struct VISIBILITY_HIDDEN RintOptimization : public UnaryDoubleFPOptimizer {
1961 : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
1963 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1965 // If this is a float argument passed in, convert to rintf.
1966 if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
1969 return false; // opt failed
1973 struct VISIBILITY_HIDDEN NearByIntOptimization : public UnaryDoubleFPOptimizer {
1974 NearByIntOptimization()
1975 : UnaryDoubleFPOptimizer("nearbyint",
1976 "Number of 'nearbyint' calls simplified") {}
1978 virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
1979 #ifdef HAVE_NEARBYINTF
1980 // If this is a float argument passed in, convert to nearbyintf.
1981 if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
1984 return false; // opt failed
1986 } NearByIntOptimizer;
1988 /// GetConstantStringInfo - This function computes the length of a
1989 /// null-terminated constant array of integers. This function can't rely on the
1990 /// size of the constant array because there could be a null terminator in the
1991 /// middle of the array.
1993 /// We also have to bail out if we find a non-integer constant initializer
1994 /// of one of the elements or if there is no null-terminator. The logic
1995 /// below checks each of these conditions and will return true only if all
1996 /// conditions are met. If the conditions aren't met, this returns false.
1998 /// If successful, the \p Array param is set to the constant array being
1999 /// indexed, the \p Length parameter is set to the length of the null-terminated
2000 /// string pointed to by V, the \p StartIdx value is set to the first
2001 /// element of the Array that V points to, and true is returned.
2002 static bool GetConstantStringInfo(Value *V, ConstantArray *&Array,
2003 uint64_t &Length, uint64_t &StartIdx) {
2004 assert(V != 0 && "Invalid args to GetConstantStringInfo");
2005 // Initialize results.
2011 // If the value is not a GEP instruction nor a constant expression with a
2012 // GEP instruction, then return false because ConstantArray can't occur
2014 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
2016 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
2017 if (CE->getOpcode() != Instruction::GetElementPtr)
2024 // Make sure the GEP has exactly three arguments.
2025 if (GEP->getNumOperands() != 3)
2028 // Check to make sure that the first operand of the GEP is an integer and
2029 // has value 0 so that we are sure we're indexing into the initializer.
2030 if (ConstantInt* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
2036 // If the second index isn't a ConstantInt, then this is a variable index
2037 // into the array. If this occurs, we can't say anything meaningful about
2040 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
2041 StartIdx = CI->getZExtValue();
2045 // The GEP instruction, constant or instruction, must reference a global
2046 // variable that is a constant and is initialized. The referenced constant
2047 // initializer is the array that we'll use for optimization.
2048 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
2049 if (!GV || !GV->isConstant() || !GV->hasInitializer())
2051 Constant *GlobalInit = GV->getInitializer();
2053 // Handle the ConstantAggregateZero case
2054 if (isa<ConstantAggregateZero>(GlobalInit)) {
2055 // This is a degenerate case. The initializer is constant zero so the
2056 // length of the string must be zero.
2061 // Must be a Constant Array
2062 Array = dyn_cast<ConstantArray>(GlobalInit);
2063 if (!Array) return false;
2065 // Get the number of elements in the array
2066 uint64_t NumElts = Array->getType()->getNumElements();
2068 // Traverse the constant array from start_idx (derived above) which is
2069 // the place the GEP refers to in the array.
2072 if (Length >= NumElts)
2073 return false; // The array isn't null terminated.
2075 Constant *Elt = Array->getOperand(Length);
2076 if (ConstantInt *CI = dyn_cast<ConstantInt>(Elt)) {
2077 // Check for the null terminator.
2079 break; // we found end of string
2081 return false; // This array isn't suitable, non-int initializer
2085 // Subtract out the initial value from the length
2087 return true; // success!
2090 /// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
2091 /// inserting the cast before IP, and return the cast.
2092 /// @brief Cast a value to a "C" string.
2093 static Value *CastToCStr(Value *V, Instruction &IP) {
2094 assert(isa<PointerType>(V->getType()) &&
2095 "Can't cast non-pointer type to C string type");
2096 const Type *SBPTy = PointerType::get(Type::Int8Ty);
2097 if (V->getType() != SBPTy)
2098 return new BitCastInst(V, SBPTy, V->getName(), &IP);
2103 // Additional cases that we need to add to this file:
2106 // * cbrt(expN(X)) -> expN(x/3)
2107 // * cbrt(sqrt(x)) -> pow(x,1/6)
2108 // * cbrt(sqrt(x)) -> pow(x,1/9)
2111 // * cos(-x) -> cos(x)
2114 // * exp(log(x)) -> x
2117 // * log(exp(x)) -> x
2118 // * log(x**y) -> y*log(x)
2119 // * log(exp(y)) -> y*log(e)
2120 // * log(exp2(y)) -> y*log(2)
2121 // * log(exp10(y)) -> y*log(10)
2122 // * log(sqrt(x)) -> 0.5*log(x)
2123 // * log(pow(x,y)) -> y*log(x)
2125 // lround, lroundf, lroundl:
2126 // * lround(cnst) -> cnst'
2129 // * memcmp(x,y,l) -> cnst
2130 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
2133 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
2134 // (if s is a global constant array)
2137 // * pow(exp(x),y) -> exp(x*y)
2138 // * pow(sqrt(x),y) -> pow(x,y*0.5)
2139 // * pow(pow(x,y),z)-> pow(x,y*z)
2142 // * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
2144 // round, roundf, roundl:
2145 // * round(cnst) -> cnst'
2148 // * signbit(cnst) -> cnst'
2149 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2151 // sqrt, sqrtf, sqrtl:
2152 // * sqrt(expN(x)) -> expN(x*0.5)
2153 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2154 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2157 // * stpcpy(str, "literal") ->
2158 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
2160 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
2161 // (if c is a constant integer and s is a constant string)
2162 // * strrchr(s1,0) -> strchr(s1,0)
2165 // * strncat(x,y,0) -> x
2166 // * strncat(x,y,0) -> x (if strlen(y) = 0)
2167 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
2170 // * strncpy(d,s,0) -> d
2171 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
2172 // (if s and l are constants)
2175 // * strpbrk(s,a) -> offset_in_for(s,a)
2176 // (if s and a are both constant strings)
2177 // * strpbrk(s,"") -> 0
2178 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
2181 // * strspn(s,a) -> const_int (if both args are constant)
2182 // * strspn("",a) -> 0
2183 // * strspn(s,"") -> 0
2184 // * strcspn(s,a) -> const_int (if both args are constant)
2185 // * strcspn("",a) -> 0
2186 // * strcspn(s,"") -> strlen(a)
2189 // * strstr(x,x) -> x
2190 // * strstr(s1,s2) -> offset_of_s2_in(s1)
2191 // (if s1 and s2 are constant strings)
2194 // * tan(atan(x)) -> x
2196 // trunc, truncf, truncl:
2197 // * trunc(cnst) -> cnst'