1 //===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a simple 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/Transforms/Scalar.h"
22 #include "llvm/Intrinsics.h"
23 #include "llvm/Module.h"
24 #include "llvm/Pass.h"
25 #include "llvm/Support/IRBuilder.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/ADT/SmallPtrSet.h"
28 #include "llvm/ADT/StringMap.h"
29 #include "llvm/ADT/Statistic.h"
30 #include "llvm/Support/Compiler.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Config/config.h"
35 STATISTIC(NumSimplified, "Number of library calls simplified");
37 //===----------------------------------------------------------------------===//
38 // Optimizer Base Class
39 //===----------------------------------------------------------------------===//
41 /// This class is the abstract base class for the set of optimizations that
42 /// corresponds to one library call.
44 class VISIBILITY_HIDDEN LibCallOptimization {
49 LibCallOptimization() { }
50 virtual ~LibCallOptimization() {}
52 /// CallOptimizer - This pure virtual method is implemented by base classes to
53 /// do various optimizations. If this returns null then no transformation was
54 /// performed. If it returns CI, then it transformed the call and CI is to be
55 /// deleted. If it returns something else, replace CI with the new value and
57 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) =0;
59 Value *OptimizeCall(CallInst *CI, const TargetData &TD, IRBuilder &B) {
60 Caller = CI->getParent()->getParent();
62 return CallOptimizer(CI->getCalledFunction(), CI, B);
65 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
66 Value *CastToCStr(Value *V, IRBuilder &B);
68 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
69 /// specified pointer. Ptr is required to be some pointer type, and the
70 /// return value has 'intptr_t' type.
71 Value *EmitStrLen(Value *Ptr, IRBuilder &B);
73 /// EmitMemCpy - Emit a call to the memcpy function to the builder. This
74 /// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
75 Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len,
76 unsigned Align, IRBuilder &B);
78 /// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
79 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
80 Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder &B);
82 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
83 /// 'floor'). This function is known to take a single of type matching 'Op'
84 /// and returns one value with the same type. If 'Op' is a long double, 'l'
85 /// is added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
86 Value *EmitUnaryFloatFnCall(Value *Op, const char *Name, IRBuilder &B);
88 /// EmitPutChar - Emit a call to the putchar function. This assumes that Char
90 void EmitPutChar(Value *Char, IRBuilder &B);
92 /// EmitPutS - Emit a call to the puts function. This assumes that Str is
94 void EmitPutS(Value *Str, IRBuilder &B);
96 /// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
97 /// an i32, and File is a pointer to FILE.
98 void EmitFPutC(Value *Char, Value *File, IRBuilder &B);
100 /// EmitFPutS - Emit a call to the puts function. Str is required to be a
101 /// pointer and File is a pointer to FILE.
102 void EmitFPutS(Value *Str, Value *File, IRBuilder &B);
104 /// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
105 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
106 void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder &B);
109 } // End anonymous namespace.
111 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
112 Value *LibCallOptimization::CastToCStr(Value *V, IRBuilder &B) {
113 return B.CreateBitCast(V, PointerType::getUnqual(Type::Int8Ty), "cstr");
116 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
117 /// specified pointer. This always returns an integer value of size intptr_t.
118 Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder &B) {
119 Module *M = Caller->getParent();
120 Constant *StrLen =M->getOrInsertFunction("strlen", TD->getIntPtrType(),
121 PointerType::getUnqual(Type::Int8Ty),
123 return B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
126 /// EmitMemCpy - Emit a call to the memcpy function to the builder. This always
127 /// expects that the size has type 'intptr_t' and Dst/Src are pointers.
128 Value *LibCallOptimization::EmitMemCpy(Value *Dst, Value *Src, Value *Len,
129 unsigned Align, IRBuilder &B) {
130 Module *M = Caller->getParent();
131 Intrinsic::ID IID = TD->getIntPtrType() == Type::Int32Ty ?
132 Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64;
133 Value *MemCpy = Intrinsic::getDeclaration(M, IID);
134 return B.CreateCall4(MemCpy, CastToCStr(Dst, B), CastToCStr(Src, B), Len,
135 ConstantInt::get(Type::Int32Ty, Align));
138 /// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
139 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
140 Value *LibCallOptimization::EmitMemChr(Value *Ptr, Value *Val,
141 Value *Len, IRBuilder &B) {
142 Module *M = Caller->getParent();
143 Value *MemChr = M->getOrInsertFunction("memchr",
144 PointerType::getUnqual(Type::Int8Ty),
145 PointerType::getUnqual(Type::Int8Ty),
146 Type::Int32Ty, TD->getIntPtrType(),
148 return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
151 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
152 /// 'floor'). This function is known to take a single of type matching 'Op' and
153 /// returns one value with the same type. If 'Op' is a long double, 'l' is
154 /// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
155 Value *LibCallOptimization::EmitUnaryFloatFnCall(Value *Op, const char *Name,
158 if (Op->getType() != Type::DoubleTy) {
159 // If we need to add a suffix, copy into NameBuffer.
160 unsigned NameLen = strlen(Name);
161 assert(NameLen < sizeof(NameBuffer)-2);
162 memcpy(NameBuffer, Name, NameLen);
163 if (Op->getType() == Type::FloatTy)
164 NameBuffer[NameLen] = 'f'; // floorf
166 NameBuffer[NameLen] = 'l'; // floorl
167 NameBuffer[NameLen+1] = 0;
171 Module *M = Caller->getParent();
172 Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
173 Op->getType(), NULL);
174 return B.CreateCall(Callee, Op, Name);
177 /// EmitPutChar - Emit a call to the putchar function. This assumes that Char
179 void LibCallOptimization::EmitPutChar(Value *Char, IRBuilder &B) {
180 Module *M = Caller->getParent();
181 Value *F = M->getOrInsertFunction("putchar", Type::Int32Ty,
182 Type::Int32Ty, NULL);
183 B.CreateCall(F, B.CreateIntCast(Char, Type::Int32Ty, "chari"), "putchar");
186 /// EmitPutS - Emit a call to the puts function. This assumes that Str is
188 void LibCallOptimization::EmitPutS(Value *Str, IRBuilder &B) {
189 Module *M = Caller->getParent();
190 Value *F = M->getOrInsertFunction("puts", Type::Int32Ty,
191 PointerType::getUnqual(Type::Int8Ty), NULL);
192 B.CreateCall(F, CastToCStr(Str, B), "puts");
195 /// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
196 /// an integer and File is a pointer to FILE.
197 void LibCallOptimization::EmitFPutC(Value *Char, Value *File, IRBuilder &B) {
198 Module *M = Caller->getParent();
199 Constant *F = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
200 File->getType(), NULL);
201 Char = B.CreateIntCast(Char, Type::Int32Ty, "chari");
202 B.CreateCall2(F, Char, File, "fputc");
205 /// EmitFPutS - Emit a call to the puts function. Str is required to be a
206 /// pointer and File is a pointer to FILE.
207 void LibCallOptimization::EmitFPutS(Value *Str, Value *File, IRBuilder &B) {
208 Module *M = Caller->getParent();
209 Constant *F = M->getOrInsertFunction("fputs", Type::Int32Ty,
210 PointerType::getUnqual(Type::Int8Ty),
211 File->getType(), NULL);
212 B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
215 /// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
216 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
217 void LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File,
219 Module *M = Caller->getParent();
220 Constant *F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
221 PointerType::getUnqual(Type::Int8Ty),
222 TD->getIntPtrType(), TD->getIntPtrType(),
223 File->getType(), NULL);
224 B.CreateCall4(F, CastToCStr(Ptr, B), Size,
225 ConstantInt::get(TD->getIntPtrType(), 1), File);
228 //===----------------------------------------------------------------------===//
230 //===----------------------------------------------------------------------===//
232 /// GetConstantStringInfo - This function computes the length of a
233 /// null-terminated C string pointed to by V. If successful, it returns true
234 /// and returns the string in Str. If unsuccessful, it returns false.
235 static bool GetConstantStringInfo(Value *V, std::string &Str) {
236 // Look bitcast instructions.
237 if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
238 return GetConstantStringInfo(BCI->getOperand(0), Str);
240 // If the value is not a GEP instruction nor a constant expression with a
241 // GEP instruction, then return false because ConstantArray can't occur
244 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
246 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
247 if (CE->getOpcode() != Instruction::GetElementPtr)
254 // Make sure the GEP has exactly three arguments.
255 if (GEP->getNumOperands() != 3)
258 // Check to make sure that the first operand of the GEP is an integer and
259 // has value 0 so that we are sure we're indexing into the initializer.
260 if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
266 // If the second index isn't a ConstantInt, then this is a variable index
267 // into the array. If this occurs, we can't say anything meaningful about
269 uint64_t StartIdx = 0;
270 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
271 StartIdx = CI->getZExtValue();
275 // The GEP instruction, constant or instruction, must reference a global
276 // variable that is a constant and is initialized. The referenced constant
277 // initializer is the array that we'll use for optimization.
278 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
279 if (!GV || !GV->isConstant() || !GV->hasInitializer())
281 Constant *GlobalInit = GV->getInitializer();
283 // Handle the ConstantAggregateZero case
284 if (isa<ConstantAggregateZero>(GlobalInit)) {
285 // This is a degenerate case. The initializer is constant zero so the
286 // length of the string must be zero.
291 // Must be a Constant Array
292 ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
293 if (Array == 0 || Array->getType()->getElementType() != Type::Int8Ty)
296 // Get the number of elements in the array
297 uint64_t NumElts = Array->getType()->getNumElements();
299 // Traverse the constant array from StartIdx (derived above) which is
300 // the place the GEP refers to in the array.
301 for (unsigned i = StartIdx; i < NumElts; ++i) {
302 Constant *Elt = Array->getOperand(i);
303 ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
304 if (!CI) // This array isn't suitable, non-int initializer.
307 return true; // we found end of string, success!
308 Str += (char)CI->getZExtValue();
311 return false; // The array isn't null terminated.
314 /// GetStringLengthH - If we can compute the length of the string pointed to by
315 /// the specified pointer, return 'len+1'. If we can't, return 0.
316 static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
317 // Look through noop bitcast instructions.
318 if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
319 return GetStringLengthH(BCI->getOperand(0), PHIs);
321 // If this is a PHI node, there are two cases: either we have already seen it
323 if (PHINode *PN = dyn_cast<PHINode>(V)) {
324 if (!PHIs.insert(PN))
325 return ~0ULL; // already in the set.
327 // If it was new, see if all the input strings are the same length.
328 uint64_t LenSoFar = ~0ULL;
329 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
330 uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
331 if (Len == 0) return 0; // Unknown length -> unknown.
333 if (Len == ~0ULL) continue;
335 if (Len != LenSoFar && LenSoFar != ~0ULL)
336 return 0; // Disagree -> unknown.
340 // Success, all agree.
344 // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
345 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
346 uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
347 if (Len1 == 0) return 0;
348 uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
349 if (Len2 == 0) return 0;
350 if (Len1 == ~0ULL) return Len2;
351 if (Len2 == ~0ULL) return Len1;
352 if (Len1 != Len2) return 0;
356 // If the value is not a GEP instruction nor a constant expression with a
357 // GEP instruction, then return unknown.
359 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
361 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
362 if (CE->getOpcode() != Instruction::GetElementPtr)
369 // Make sure the GEP has exactly three arguments.
370 if (GEP->getNumOperands() != 3)
373 // Check to make sure that the first operand of the GEP is an integer and
374 // has value 0 so that we are sure we're indexing into the initializer.
375 if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
381 // If the second index isn't a ConstantInt, then this is a variable index
382 // into the array. If this occurs, we can't say anything meaningful about
384 uint64_t StartIdx = 0;
385 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
386 StartIdx = CI->getZExtValue();
390 // The GEP instruction, constant or instruction, must reference a global
391 // variable that is a constant and is initialized. The referenced constant
392 // initializer is the array that we'll use for optimization.
393 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
394 if (!GV || !GV->isConstant() || !GV->hasInitializer())
396 Constant *GlobalInit = GV->getInitializer();
398 // Handle the ConstantAggregateZero case, which is a degenerate case. The
399 // initializer is constant zero so the length of the string must be zero.
400 if (isa<ConstantAggregateZero>(GlobalInit))
401 return 1; // Len = 0 offset by 1.
403 // Must be a Constant Array
404 ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
405 if (!Array || Array->getType()->getElementType() != Type::Int8Ty)
408 // Get the number of elements in the array
409 uint64_t NumElts = Array->getType()->getNumElements();
411 // Traverse the constant array from StartIdx (derived above) which is
412 // the place the GEP refers to in the array.
413 for (unsigned i = StartIdx; i != NumElts; ++i) {
414 Constant *Elt = Array->getOperand(i);
415 ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
416 if (!CI) // This array isn't suitable, non-int initializer.
419 return i-StartIdx+1; // We found end of string, success!
422 return 0; // The array isn't null terminated, conservatively return 'unknown'.
425 /// GetStringLength - If we can compute the length of the string pointed to by
426 /// the specified pointer, return 'len+1'. If we can't, return 0.
427 static uint64_t GetStringLength(Value *V) {
428 if (!isa<PointerType>(V->getType())) return 0;
430 SmallPtrSet<PHINode*, 32> PHIs;
431 uint64_t Len = GetStringLengthH(V, PHIs);
432 // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
433 // an empty string as a length.
434 return Len == ~0ULL ? 1 : Len;
437 /// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
438 /// value is equal or not-equal to zero.
439 static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
440 for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
442 if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
443 if (IC->isEquality())
444 if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
445 if (C->isNullValue())
447 // Unknown instruction.
453 //===----------------------------------------------------------------------===//
454 // Miscellaneous LibCall Optimizations
455 //===----------------------------------------------------------------------===//
458 //===---------------------------------------===//
459 // 'exit' Optimizations
461 /// ExitOpt - int main() { exit(4); } --> int main() { return 4; }
462 struct VISIBILITY_HIDDEN ExitOpt : public LibCallOptimization {
463 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
464 // Verify we have a reasonable prototype for exit.
465 if (Callee->arg_size() == 0 || !CI->use_empty())
468 // Verify the caller is main, and that the result type of main matches the
469 // argument type of exit.
470 if (!Caller->isName("main") || !Caller->hasExternalLinkage() ||
471 Caller->getReturnType() != CI->getOperand(1)->getType())
474 TerminatorInst *OldTI = CI->getParent()->getTerminator();
476 // Create the return after the call.
477 ReturnInst *RI = B.CreateRet(CI->getOperand(1));
479 // Drop all successor phi node entries.
480 for (unsigned i = 0, e = OldTI->getNumSuccessors(); i != e; ++i)
481 OldTI->getSuccessor(i)->removePredecessor(CI->getParent());
483 // Erase all instructions from after our return instruction until the end of
485 BasicBlock::iterator FirstDead = RI; ++FirstDead;
486 CI->getParent()->getInstList().erase(FirstDead, CI->getParent()->end());
491 //===----------------------------------------------------------------------===//
492 // String and Memory LibCall Optimizations
493 //===----------------------------------------------------------------------===//
495 //===---------------------------------------===//
496 // 'strcat' Optimizations
498 struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization {
499 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
500 // Verify the "strcat" function prototype.
501 const FunctionType *FT = Callee->getFunctionType();
502 if (FT->getNumParams() != 2 ||
503 FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
504 FT->getParamType(0) != FT->getReturnType() ||
505 FT->getParamType(1) != FT->getReturnType())
508 // Extract some information from the instruction
509 Value *Dst = CI->getOperand(1);
510 Value *Src = CI->getOperand(2);
512 // See if we can get the length of the input string.
513 uint64_t Len = GetStringLength(Src);
514 if (Len == 0) return 0;
515 --Len; // Unbias length.
517 // Handle the simple, do-nothing case: strcat(x, "") -> x
521 // We need to find the end of the destination string. That's where the
522 // memory is to be moved to. We just generate a call to strlen.
523 Value *DstLen = EmitStrLen(Dst, B);
525 // Now that we have the destination's length, we must index into the
526 // destination's pointer to get the actual memcpy destination (end of
527 // the string .. we're concatenating).
528 Dst = B.CreateGEP(Dst, DstLen, "endptr");
530 // We have enough information to now generate the memcpy call to do the
531 // concatenation for us. Make a memcpy to copy the nul byte with align = 1.
532 EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len+1), 1, B);
537 //===---------------------------------------===//
538 // 'strchr' Optimizations
540 struct VISIBILITY_HIDDEN StrChrOpt : public LibCallOptimization {
541 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
542 // Verify the "strchr" function prototype.
543 const FunctionType *FT = Callee->getFunctionType();
544 if (FT->getNumParams() != 2 ||
545 FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
546 FT->getParamType(0) != FT->getReturnType())
549 Value *SrcStr = CI->getOperand(1);
551 // If the second operand is non-constant, see if we can compute the length
552 // of the input string and turn this into memchr.
553 ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getOperand(2));
555 uint64_t Len = GetStringLength(SrcStr);
556 if (Len == 0 || FT->getParamType(1) != Type::Int32Ty) // memchr needs i32.
559 return EmitMemChr(SrcStr, CI->getOperand(2), // include nul.
560 ConstantInt::get(TD->getIntPtrType(), Len), B);
563 // Otherwise, the character is a constant, see if the first argument is
564 // a string literal. If so, we can constant fold.
566 if (!GetConstantStringInfo(SrcStr, Str))
569 // strchr can find the nul character.
571 char CharValue = CharC->getSExtValue();
573 // Compute the offset.
576 if (i == Str.size()) // Didn't find the char. strchr returns null.
577 return Constant::getNullValue(CI->getType());
578 // Did we find our match?
579 if (Str[i] == CharValue)
584 // strchr(s+n,c) -> gep(s+n+i,c)
585 Value *Idx = ConstantInt::get(Type::Int64Ty, i);
586 return B.CreateGEP(SrcStr, Idx, "strchr");
590 //===---------------------------------------===//
591 // 'strcmp' Optimizations
593 struct VISIBILITY_HIDDEN StrCmpOpt : public LibCallOptimization {
594 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
595 // Verify the "strcmp" function prototype.
596 const FunctionType *FT = Callee->getFunctionType();
597 if (FT->getNumParams() != 2 || FT->getReturnType() != Type::Int32Ty ||
598 FT->getParamType(0) != FT->getParamType(1) ||
599 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
602 Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
603 if (Str1P == Str2P) // strcmp(x,x) -> 0
604 return ConstantInt::get(CI->getType(), 0);
606 std::string Str1, Str2;
607 bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
608 bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
610 if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
611 return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
613 if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
614 return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
616 // strcmp(x, y) -> cnst (if both x and y are constant strings)
617 if (HasStr1 && HasStr2)
618 return ConstantInt::get(CI->getType(), strcmp(Str1.c_str(),Str2.c_str()));
623 //===---------------------------------------===//
624 // 'strncmp' Optimizations
626 struct VISIBILITY_HIDDEN StrNCmpOpt : public LibCallOptimization {
627 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
628 // Verify the "strncmp" function prototype.
629 const FunctionType *FT = Callee->getFunctionType();
630 if (FT->getNumParams() != 3 || FT->getReturnType() != Type::Int32Ty ||
631 FT->getParamType(0) != FT->getParamType(1) ||
632 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
633 !isa<IntegerType>(FT->getParamType(2)))
636 Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
637 if (Str1P == Str2P) // strncmp(x,x,n) -> 0
638 return ConstantInt::get(CI->getType(), 0);
640 // Get the length argument if it is constant.
642 if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
643 Length = LengthArg->getZExtValue();
647 if (Length == 0) // strncmp(x,y,0) -> 0
648 return ConstantInt::get(CI->getType(), 0);
650 std::string Str1, Str2;
651 bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
652 bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
654 if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x
655 return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
657 if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
658 return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
660 // strncmp(x, y) -> cnst (if both x and y are constant strings)
661 if (HasStr1 && HasStr2)
662 return ConstantInt::get(CI->getType(),
663 strncmp(Str1.c_str(), Str2.c_str(), Length));
669 //===---------------------------------------===//
670 // 'strcpy' Optimizations
672 struct VISIBILITY_HIDDEN StrCpyOpt : public LibCallOptimization {
673 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
674 // Verify the "strcpy" function prototype.
675 const FunctionType *FT = Callee->getFunctionType();
676 if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
677 FT->getParamType(0) != FT->getParamType(1) ||
678 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
681 Value *Dst = CI->getOperand(1), *Src = CI->getOperand(2);
682 if (Dst == Src) // strcpy(x,x) -> x
685 // See if we can get the length of the input string.
686 uint64_t Len = GetStringLength(Src);
687 if (Len == 0) return 0;
689 // We have enough information to now generate the memcpy call to do the
690 // concatenation for us. Make a memcpy to copy the nul byte with align = 1.
691 EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len), 1, B);
698 //===---------------------------------------===//
699 // 'strlen' Optimizations
701 struct VISIBILITY_HIDDEN StrLenOpt : public LibCallOptimization {
702 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
703 const FunctionType *FT = Callee->getFunctionType();
704 if (FT->getNumParams() != 1 ||
705 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
706 !isa<IntegerType>(FT->getReturnType()))
709 Value *Src = CI->getOperand(1);
711 // Constant folding: strlen("xyz") -> 3
712 if (uint64_t Len = GetStringLength(Src))
713 return ConstantInt::get(CI->getType(), Len-1);
715 // Handle strlen(p) != 0.
716 if (!IsOnlyUsedInZeroEqualityComparison(CI)) return 0;
718 // strlen(x) != 0 --> *x != 0
719 // strlen(x) == 0 --> *x == 0
720 return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType());
724 //===---------------------------------------===//
725 // 'memcmp' Optimizations
727 struct VISIBILITY_HIDDEN MemCmpOpt : public LibCallOptimization {
728 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
729 const FunctionType *FT = Callee->getFunctionType();
730 if (FT->getNumParams() != 3 || !isa<PointerType>(FT->getParamType(0)) ||
731 !isa<PointerType>(FT->getParamType(1)) ||
732 FT->getReturnType() != Type::Int32Ty)
735 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
737 if (LHS == RHS) // memcmp(s,s,x) -> 0
738 return Constant::getNullValue(CI->getType());
740 // Make sure we have a constant length.
741 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
743 uint64_t Len = LenC->getZExtValue();
745 if (Len == 0) // memcmp(s1,s2,0) -> 0
746 return Constant::getNullValue(CI->getType());
748 if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
749 Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
750 Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
751 return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
754 // memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0
755 // memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS) != 0
756 if ((Len == 2 || Len == 4) && IsOnlyUsedInZeroEqualityComparison(CI)) {
757 LHS = B.CreateBitCast(LHS, PointerType::getUnqual(Type::Int16Ty), "tmp");
758 RHS = B.CreateBitCast(RHS, LHS->getType(), "tmp");
759 LoadInst *LHSV = B.CreateLoad(LHS, "lhsv");
760 LoadInst *RHSV = B.CreateLoad(RHS, "rhsv");
761 LHSV->setAlignment(1); RHSV->setAlignment(1); // Unaligned loads.
762 return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType());
769 //===---------------------------------------===//
770 // 'memcpy' Optimizations
772 struct VISIBILITY_HIDDEN MemCpyOpt : public LibCallOptimization {
773 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
774 const FunctionType *FT = Callee->getFunctionType();
775 if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
776 !isa<PointerType>(FT->getParamType(0)) ||
777 !isa<PointerType>(FT->getParamType(1)) ||
778 FT->getParamType(2) != TD->getIntPtrType())
781 // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
782 EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
783 return CI->getOperand(1);
787 //===----------------------------------------------------------------------===//
788 // Math Library Optimizations
789 //===----------------------------------------------------------------------===//
791 //===---------------------------------------===//
792 // 'pow*' Optimizations
794 struct VISIBILITY_HIDDEN PowOpt : public LibCallOptimization {
795 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
796 const FunctionType *FT = Callee->getFunctionType();
797 // Just make sure this has 2 arguments of the same FP type, which match the
799 if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
800 FT->getParamType(0) != FT->getParamType(1) ||
801 !FT->getParamType(0)->isFloatingPoint())
804 Value *Op1 = CI->getOperand(1), *Op2 = CI->getOperand(2);
805 if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
806 if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0
808 if (Op1C->isExactlyValue(2.0)) // pow(2.0, x) -> exp2(x)
809 return EmitUnaryFloatFnCall(Op2, "exp2", B);
812 ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2);
813 if (Op2C == 0) return 0;
815 if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0
816 return ConstantFP::get(CI->getType(), 1.0);
818 if (Op2C->isExactlyValue(0.5)) {
819 // FIXME: This is not safe for -0.0 and -inf. This can only be done when
820 // 'unsafe' math optimizations are allowed.
821 // x pow(x, 0.5) sqrt(x)
822 // ---------------------------------------------
826 // pow(x, 0.5) -> sqrt(x)
827 return B.CreateCall(get_sqrt(), Op1, "sqrt");
831 if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x
833 if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x
834 return B.CreateMul(Op1, Op1, "pow2");
835 if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x
836 return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), Op1, "powrecip");
841 //===---------------------------------------===//
842 // 'exp2' Optimizations
844 struct VISIBILITY_HIDDEN Exp2Opt : public LibCallOptimization {
845 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
846 const FunctionType *FT = Callee->getFunctionType();
847 // Just make sure this has 1 argument of FP type, which matches the
849 if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
850 !FT->getParamType(0)->isFloatingPoint())
853 Value *Op = CI->getOperand(1);
854 // Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= 32
855 // Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32
857 if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) {
858 if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32)
859 LdExpArg = B.CreateSExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
860 } else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) {
861 if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32)
862 LdExpArg = B.CreateZExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
867 if (Op->getType() == Type::FloatTy)
869 else if (Op->getType() == Type::DoubleTy)
874 Constant *One = ConstantFP::get(APFloat(1.0f));
875 if (Op->getType() != Type::FloatTy)
876 One = ConstantExpr::getFPExtend(One, Op->getType());
878 Module *M = Caller->getParent();
879 Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
880 Op->getType(), Type::Int32Ty,NULL);
881 return B.CreateCall2(Callee, One, LdExpArg);
888 //===---------------------------------------===//
889 // Double -> Float Shrinking Optimizations for Unary Functions like 'floor'
891 struct VISIBILITY_HIDDEN UnaryDoubleFPOpt : public LibCallOptimization {
892 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
893 const FunctionType *FT = Callee->getFunctionType();
894 if (FT->getNumParams() != 1 || FT->getReturnType() != Type::DoubleTy ||
895 FT->getParamType(0) != Type::DoubleTy)
898 // If this is something like 'floor((double)floatval)', convert to floorf.
899 FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1));
900 if (Cast == 0 || Cast->getOperand(0)->getType() != Type::FloatTy)
903 // floor((double)floatval) -> (double)floorf(floatval)
904 Value *V = Cast->getOperand(0);
905 V = EmitUnaryFloatFnCall(V, Callee->getNameStart(), B);
906 return B.CreateFPExt(V, Type::DoubleTy);
910 //===----------------------------------------------------------------------===//
911 // Integer Optimizations
912 //===----------------------------------------------------------------------===//
914 //===---------------------------------------===//
915 // 'ffs*' Optimizations
917 struct VISIBILITY_HIDDEN FFSOpt : public LibCallOptimization {
918 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
919 const FunctionType *FT = Callee->getFunctionType();
920 // Just make sure this has 2 arguments of the same FP type, which match the
922 if (FT->getNumParams() != 1 || FT->getReturnType() != Type::Int32Ty ||
923 !isa<IntegerType>(FT->getParamType(0)))
926 Value *Op = CI->getOperand(1);
929 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
930 if (CI->getValue() == 0) // ffs(0) -> 0.
931 return Constant::getNullValue(CI->getType());
932 return ConstantInt::get(Type::Int32Ty, // ffs(c) -> cttz(c)+1
933 CI->getValue().countTrailingZeros()+1);
936 // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
937 const Type *ArgType = Op->getType();
938 Value *F = Intrinsic::getDeclaration(Callee->getParent(),
939 Intrinsic::cttz, &ArgType, 1);
940 Value *V = B.CreateCall(F, Op, "cttz");
941 V = B.CreateAdd(V, ConstantInt::get(Type::Int32Ty, 1), "tmp");
942 V = B.CreateIntCast(V, Type::Int32Ty, false, "tmp");
944 Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp");
945 return B.CreateSelect(Cond, V, ConstantInt::get(Type::Int32Ty, 0));
949 //===---------------------------------------===//
950 // 'isdigit' Optimizations
952 struct VISIBILITY_HIDDEN IsDigitOpt : public LibCallOptimization {
953 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
954 const FunctionType *FT = Callee->getFunctionType();
955 // We require integer(i32)
956 if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
957 FT->getParamType(0) != Type::Int32Ty)
960 // isdigit(c) -> (c-'0') <u 10
961 Value *Op = CI->getOperand(1);
962 Op = B.CreateSub(Op, ConstantInt::get(Type::Int32Ty, '0'), "isdigittmp");
963 Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 10), "isdigit");
964 return B.CreateZExt(Op, CI->getType());
968 //===---------------------------------------===//
969 // 'isascii' Optimizations
971 struct VISIBILITY_HIDDEN IsAsciiOpt : public LibCallOptimization {
972 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
973 const FunctionType *FT = Callee->getFunctionType();
974 // We require integer(i32)
975 if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
976 FT->getParamType(0) != Type::Int32Ty)
979 // isascii(c) -> c <u 128
980 Value *Op = CI->getOperand(1);
981 Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 128), "isascii");
982 return B.CreateZExt(Op, CI->getType());
986 //===---------------------------------------===//
987 // 'toascii' Optimizations
989 struct VISIBILITY_HIDDEN ToAsciiOpt : public LibCallOptimization {
990 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
991 const FunctionType *FT = Callee->getFunctionType();
992 // We require i32(i32)
993 if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
994 FT->getParamType(0) != Type::Int32Ty)
997 // isascii(c) -> c & 0x7f
998 return B.CreateAnd(CI->getOperand(1), ConstantInt::get(CI->getType(),0x7F));
1002 //===----------------------------------------------------------------------===//
1003 // Formatting and IO Optimizations
1004 //===----------------------------------------------------------------------===//
1006 //===---------------------------------------===//
1007 // 'printf' Optimizations
1009 struct VISIBILITY_HIDDEN PrintFOpt : public LibCallOptimization {
1010 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1011 // Require one fixed pointer argument and an integer/void result.
1012 const FunctionType *FT = Callee->getFunctionType();
1013 if (FT->getNumParams() < 1 || !isa<PointerType>(FT->getParamType(0)) ||
1014 !(isa<IntegerType>(FT->getReturnType()) ||
1015 FT->getReturnType() == Type::VoidTy))
1018 // Check for a fixed format string.
1019 std::string FormatStr;
1020 if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
1023 // Empty format string -> noop.
1024 if (FormatStr.empty()) // Tolerate printf's declared void.
1025 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 0);
1027 // printf("x") -> putchar('x'), even for '%'.
1028 if (FormatStr.size() == 1) {
1029 EmitPutChar(ConstantInt::get(Type::Int32Ty, FormatStr[0]), B);
1030 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
1033 // printf("foo\n") --> puts("foo")
1034 if (FormatStr[FormatStr.size()-1] == '\n' &&
1035 FormatStr.find('%') == std::string::npos) { // no format characters.
1036 // Create a string literal with no \n on it. We expect the constant merge
1037 // pass to be run after this pass, to merge duplicate strings.
1038 FormatStr.erase(FormatStr.end()-1);
1039 Constant *C = ConstantArray::get(FormatStr, true);
1040 C = new GlobalVariable(C->getType(), true,GlobalVariable::InternalLinkage,
1041 C, "str", Callee->getParent());
1043 return CI->use_empty() ? (Value*)CI :
1044 ConstantInt::get(CI->getType(), FormatStr.size()+1);
1047 // Optimize specific format strings.
1048 // printf("%c", chr) --> putchar(*(i8*)dst)
1049 if (FormatStr == "%c" && CI->getNumOperands() > 2 &&
1050 isa<IntegerType>(CI->getOperand(2)->getType())) {
1051 EmitPutChar(CI->getOperand(2), B);
1052 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
1055 // printf("%s\n", str) --> puts(str)
1056 if (FormatStr == "%s\n" && CI->getNumOperands() > 2 &&
1057 isa<PointerType>(CI->getOperand(2)->getType()) &&
1059 EmitPutS(CI->getOperand(2), B);
1066 //===---------------------------------------===//
1067 // 'sprintf' Optimizations
1069 struct VISIBILITY_HIDDEN SPrintFOpt : public LibCallOptimization {
1070 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1071 // Require two fixed pointer arguments and an integer result.
1072 const FunctionType *FT = Callee->getFunctionType();
1073 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1074 !isa<PointerType>(FT->getParamType(1)) ||
1075 !isa<IntegerType>(FT->getReturnType()))
1078 // Check for a fixed format string.
1079 std::string FormatStr;
1080 if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
1083 // If we just have a format string (nothing else crazy) transform it.
1084 if (CI->getNumOperands() == 3) {
1085 // Make sure there's no % in the constant array. We could try to handle
1086 // %% -> % in the future if we cared.
1087 for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1088 if (FormatStr[i] == '%')
1089 return 0; // we found a format specifier, bail out.
1091 // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
1092 EmitMemCpy(CI->getOperand(1), CI->getOperand(2), // Copy the nul byte.
1093 ConstantInt::get(TD->getIntPtrType(), FormatStr.size()+1),1,B);
1094 return ConstantInt::get(CI->getType(), FormatStr.size());
1097 // The remaining optimizations require the format string to be "%s" or "%c"
1098 // and have an extra operand.
1099 if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
1102 // Decode the second character of the format string.
1103 if (FormatStr[1] == 'c') {
1104 // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
1105 if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
1106 Value *V = B.CreateTrunc(CI->getOperand(3), Type::Int8Ty, "char");
1107 Value *Ptr = CastToCStr(CI->getOperand(1), B);
1108 B.CreateStore(V, Ptr);
1109 Ptr = B.CreateGEP(Ptr, ConstantInt::get(Type::Int32Ty, 1), "nul");
1110 B.CreateStore(Constant::getNullValue(Type::Int8Ty), Ptr);
1112 return ConstantInt::get(CI->getType(), 1);
1115 if (FormatStr[1] == 's') {
1116 // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1117 if (!isa<PointerType>(CI->getOperand(3)->getType())) return 0;
1119 Value *Len = EmitStrLen(CI->getOperand(3), B);
1120 Value *IncLen = B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1),
1122 EmitMemCpy(CI->getOperand(1), CI->getOperand(3), IncLen, 1, B);
1124 // The sprintf result is the unincremented number of bytes in the string.
1125 return B.CreateIntCast(Len, CI->getType(), false);
1131 //===---------------------------------------===//
1132 // 'fwrite' Optimizations
1134 struct VISIBILITY_HIDDEN FWriteOpt : public LibCallOptimization {
1135 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1136 // Require a pointer, an integer, an integer, a pointer, returning integer.
1137 const FunctionType *FT = Callee->getFunctionType();
1138 if (FT->getNumParams() != 4 || !isa<PointerType>(FT->getParamType(0)) ||
1139 !isa<IntegerType>(FT->getParamType(1)) ||
1140 !isa<IntegerType>(FT->getParamType(2)) ||
1141 !isa<PointerType>(FT->getParamType(3)) ||
1142 !isa<IntegerType>(FT->getReturnType()))
1145 // Get the element size and count.
1146 ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getOperand(2));
1147 ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getOperand(3));
1148 if (!SizeC || !CountC) return 0;
1149 uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
1151 // If this is writing zero records, remove the call (it's a noop).
1153 return ConstantInt::get(CI->getType(), 0);
1155 // If this is writing one byte, turn it into fputc.
1156 if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F)
1157 Value *Char = B.CreateLoad(CastToCStr(CI->getOperand(1), B), "char");
1158 EmitFPutC(Char, CI->getOperand(4), B);
1159 return ConstantInt::get(CI->getType(), 1);
1166 //===---------------------------------------===//
1167 // 'fputs' Optimizations
1169 struct VISIBILITY_HIDDEN FPutsOpt : public LibCallOptimization {
1170 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1171 // Require two pointers. Also, we can't optimize if return value is used.
1172 const FunctionType *FT = Callee->getFunctionType();
1173 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1174 !isa<PointerType>(FT->getParamType(1)) ||
1178 // fputs(s,F) --> fwrite(s,1,strlen(s),F)
1179 uint64_t Len = GetStringLength(CI->getOperand(1));
1181 EmitFWrite(CI->getOperand(1), ConstantInt::get(TD->getIntPtrType(), Len-1),
1182 CI->getOperand(2), B);
1183 return CI; // Known to have no uses (see above).
1187 //===---------------------------------------===//
1188 // 'fprintf' Optimizations
1190 struct VISIBILITY_HIDDEN FPrintFOpt : public LibCallOptimization {
1191 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1192 // Require two fixed paramters as pointers and integer result.
1193 const FunctionType *FT = Callee->getFunctionType();
1194 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1195 !isa<PointerType>(FT->getParamType(1)) ||
1196 !isa<IntegerType>(FT->getReturnType()))
1199 // All the optimizations depend on the format string.
1200 std::string FormatStr;
1201 if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
1204 // fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
1205 if (CI->getNumOperands() == 3) {
1206 for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1207 if (FormatStr[i] == '%') // Could handle %% -> % if we cared.
1208 return 0; // We found a format specifier.
1210 EmitFWrite(CI->getOperand(2), ConstantInt::get(TD->getIntPtrType(),
1212 CI->getOperand(1), B);
1213 return ConstantInt::get(CI->getType(), FormatStr.size());
1216 // The remaining optimizations require the format string to be "%s" or "%c"
1217 // and have an extra operand.
1218 if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
1221 // Decode the second character of the format string.
1222 if (FormatStr[1] == 'c') {
1223 // fprintf(F, "%c", chr) --> *(i8*)dst = chr
1224 if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
1225 EmitFPutC(CI->getOperand(3), CI->getOperand(1), B);
1226 return ConstantInt::get(CI->getType(), 1);
1229 if (FormatStr[1] == 's') {
1230 // fprintf(F, "%s", str) -> fputs(str, F)
1231 if (!isa<PointerType>(CI->getOperand(3)->getType()) || !CI->use_empty())
1233 EmitFPutS(CI->getOperand(3), CI->getOperand(1), B);
1240 } // end anonymous namespace.
1242 //===----------------------------------------------------------------------===//
1243 // SimplifyLibCalls Pass Implementation
1244 //===----------------------------------------------------------------------===//
1247 /// This pass optimizes well known library functions from libc and libm.
1249 class VISIBILITY_HIDDEN SimplifyLibCalls : public FunctionPass {
1250 StringMap<LibCallOptimization*> Optimizations;
1251 // Miscellaneous LibCall Optimizations
1253 // String and Memory LibCall Optimizations
1254 StrCatOpt StrCat; StrChrOpt StrChr; StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
1255 StrCpyOpt StrCpy; StrLenOpt StrLen; MemCmpOpt MemCmp; MemCpyOpt MemCpy;
1256 // Math Library Optimizations
1257 PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
1258 // Integer Optimizations
1259 FFSOpt FFS; IsDigitOpt IsDigit; IsAsciiOpt IsAscii; ToAsciiOpt ToAscii;
1260 // Formatting and IO Optimizations
1261 SPrintFOpt SPrintF; PrintFOpt PrintF;
1262 FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF;
1264 static char ID; // Pass identification
1265 SimplifyLibCalls() : FunctionPass((intptr_t)&ID) {}
1267 void InitOptimizations();
1268 bool runOnFunction(Function &F);
1270 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1271 AU.addRequired<TargetData>();
1274 char SimplifyLibCalls::ID = 0;
1275 } // end anonymous namespace.
1277 static RegisterPass<SimplifyLibCalls>
1278 X("simplify-libcalls", "Simplify well-known library calls");
1280 // Public interface to the Simplify LibCalls pass.
1281 FunctionPass *llvm::createSimplifyLibCallsPass() {
1282 return new SimplifyLibCalls();
1285 /// Optimizations - Populate the Optimizations map with all the optimizations
1287 void SimplifyLibCalls::InitOptimizations() {
1288 // Miscellaneous LibCall Optimizations
1289 Optimizations["exit"] = &Exit;
1291 // String and Memory LibCall Optimizations
1292 Optimizations["strcat"] = &StrCat;
1293 Optimizations["strchr"] = &StrChr;
1294 Optimizations["strcmp"] = &StrCmp;
1295 Optimizations["strncmp"] = &StrNCmp;
1296 Optimizations["strcpy"] = &StrCpy;
1297 Optimizations["strlen"] = &StrLen;
1298 Optimizations["memcmp"] = &MemCmp;
1299 Optimizations["memcpy"] = &MemCpy;
1301 // Math Library Optimizations
1302 Optimizations["powf"] = &Pow;
1303 Optimizations["pow"] = &Pow;
1304 Optimizations["powl"] = &Pow;
1305 Optimizations["exp2l"] = &Exp2;
1306 Optimizations["exp2"] = &Exp2;
1307 Optimizations["exp2f"] = &Exp2;
1310 Optimizations["floor"] = &UnaryDoubleFP;
1313 Optimizations["ceil"] = &UnaryDoubleFP;
1316 Optimizations["round"] = &UnaryDoubleFP;
1319 Optimizations["rint"] = &UnaryDoubleFP;
1321 #ifdef HAVE_NEARBYINTF
1322 Optimizations["nearbyint"] = &UnaryDoubleFP;
1325 // Integer Optimizations
1326 Optimizations["ffs"] = &FFS;
1327 Optimizations["ffsl"] = &FFS;
1328 Optimizations["ffsll"] = &FFS;
1329 Optimizations["isdigit"] = &IsDigit;
1330 Optimizations["isascii"] = &IsAscii;
1331 Optimizations["toascii"] = &ToAscii;
1333 // Formatting and IO Optimizations
1334 Optimizations["sprintf"] = &SPrintF;
1335 Optimizations["printf"] = &PrintF;
1336 Optimizations["fwrite"] = &FWrite;
1337 Optimizations["fputs"] = &FPuts;
1338 Optimizations["fprintf"] = &FPrintF;
1342 /// runOnFunction - Top level algorithm.
1344 bool SimplifyLibCalls::runOnFunction(Function &F) {
1345 if (Optimizations.empty())
1346 InitOptimizations();
1348 const TargetData &TD = getAnalysis<TargetData>();
1352 bool Changed = false;
1353 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
1354 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
1355 // Ignore non-calls.
1356 CallInst *CI = dyn_cast<CallInst>(I++);
1359 // Ignore indirect calls and calls to non-external functions.
1360 Function *Callee = CI->getCalledFunction();
1361 if (Callee == 0 || !Callee->isDeclaration() ||
1362 !(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage()))
1365 // Ignore unknown calls.
1366 const char *CalleeName = Callee->getNameStart();
1367 StringMap<LibCallOptimization*>::iterator OMI =
1368 Optimizations.find(CalleeName, CalleeName+Callee->getNameLen());
1369 if (OMI == Optimizations.end()) continue;
1371 // Set the builder to the instruction after the call.
1372 Builder.SetInsertPoint(BB, I);
1374 // Try to optimize this call.
1375 Value *Result = OMI->second->OptimizeCall(CI, TD, Builder);
1376 if (Result == 0) continue;
1378 DEBUG(DOUT << "SimplifyLibCalls simplified: " << *CI;
1379 DOUT << " into: " << *Result << "\n");
1381 // Something changed!
1385 // Inspect the instruction after the call (which was potentially just
1389 if (CI != Result && !CI->use_empty()) {
1390 CI->replaceAllUsesWith(Result);
1391 if (!Result->hasName())
1392 Result->takeName(CI);
1394 CI->eraseFromParent();
1402 // Additional cases that we need to add to this file:
1405 // * cbrt(expN(X)) -> expN(x/3)
1406 // * cbrt(sqrt(x)) -> pow(x,1/6)
1407 // * cbrt(sqrt(x)) -> pow(x,1/9)
1410 // * cos(-x) -> cos(x)
1413 // * exp(log(x)) -> x
1416 // * log(exp(x)) -> x
1417 // * log(x**y) -> y*log(x)
1418 // * log(exp(y)) -> y*log(e)
1419 // * log(exp2(y)) -> y*log(2)
1420 // * log(exp10(y)) -> y*log(10)
1421 // * log(sqrt(x)) -> 0.5*log(x)
1422 // * log(pow(x,y)) -> y*log(x)
1424 // lround, lroundf, lroundl:
1425 // * lround(cnst) -> cnst'
1428 // * memcmp(x,y,l) -> cnst
1429 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
1432 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
1433 // (if s is a global constant array)
1436 // * pow(exp(x),y) -> exp(x*y)
1437 // * pow(sqrt(x),y) -> pow(x,y*0.5)
1438 // * pow(pow(x,y),z)-> pow(x,y*z)
1441 // * puts("") -> putchar("\n")
1443 // round, roundf, roundl:
1444 // * round(cnst) -> cnst'
1447 // * signbit(cnst) -> cnst'
1448 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
1450 // sqrt, sqrtf, sqrtl:
1451 // * sqrt(expN(x)) -> expN(x*0.5)
1452 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
1453 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
1456 // * stpcpy(str, "literal") ->
1457 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
1459 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
1460 // (if c is a constant integer and s is a constant string)
1461 // * strrchr(s1,0) -> strchr(s1,0)
1464 // * strncat(x,y,0) -> x
1465 // * strncat(x,y,0) -> x (if strlen(y) = 0)
1466 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
1469 // * strncpy(d,s,0) -> d
1470 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
1471 // (if s and l are constants)
1474 // * strpbrk(s,a) -> offset_in_for(s,a)
1475 // (if s and a are both constant strings)
1476 // * strpbrk(s,"") -> 0
1477 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
1480 // * strspn(s,a) -> const_int (if both args are constant)
1481 // * strspn("",a) -> 0
1482 // * strspn(s,"") -> 0
1483 // * strcspn(s,a) -> const_int (if both args are constant)
1484 // * strcspn("",a) -> 0
1485 // * strcspn(s,"") -> strlen(a)
1488 // * strstr(x,x) -> x
1489 // * strstr(s1,s2) -> offset_of_s2_in(s1)
1490 // (if s1 and s2 are constant strings)
1493 // * tan(atan(x)) -> x
1495 // trunc, truncf, truncl:
1496 // * trunc(cnst) -> cnst'