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[SimplifyLibCalls] Garbage collect dead code.

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We already skip optimizations if the return value
of printf() is used, so CI->use_empty() is always
true.

Differential Revision:  http://reviews.llvm.org/D18656


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265253 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Davide Italiano 2016-04-03 01:46:52 +00:00
parent 5a07bd0af6
commit 4e5a97a04b
1 changed files with 7 additions and 28 deletions
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35
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@ -1832,12 +1832,8 @@ Value *LibCallSimplifier::optimizePrintFString(CallInst *CI, IRBuilder<> &B) {
return nullptr;
// printf("x") -> putchar('x'), even for '%'.
if (FormatStr.size() == 1) {
Value *Res = emitPutChar(B.getInt32(FormatStr[0]), B, TLI);
if (CI->use_empty() || !Res)
return Res;
return B.CreateIntCast(Res, CI->getType(), true);
}
if (FormatStr.size() == 1)
return emitPutChar(B.getInt32(FormatStr[0]), B, TLI);
// printf("%s", "a") --> putchar('a')
if (FormatStr == "%s" && CI->getNumArgOperands() > 1) {
@ -1846,15 +1842,7 @@ Value *LibCallSimplifier::optimizePrintFString(CallInst *CI, IRBuilder<> &B) {
return nullptr;
if (ChrStr.size() != 1)
return nullptr;
Value *Res = emitPutChar(B.getInt32(ChrStr[0]), B, TLI);
// FIXME: Here we check that the return value is not used
// but ealier we prevent transformations in case it is.
// This should probably be an assert.
if (CI->use_empty() || !Res)
return Res;
return B.CreateIntCast(Res, CI->getType(), true);
return emitPutChar(B.getInt32(ChrStr[0]), B, TLI);
}
// printf("foo\n") --> puts("foo")
@ -1864,28 +1852,19 @@ Value *LibCallSimplifier::optimizePrintFString(CallInst *CI, IRBuilder<> &B) {
// pass to be run after this pass, to merge duplicate strings.
FormatStr = FormatStr.drop_back();
Value *GV = B.CreateGlobalString(FormatStr, "str");
Value *NewCI = emitPutS(GV, B, TLI);
return (CI->use_empty() || !NewCI)
? NewCI
: ConstantInt::get(CI->getType(), FormatStr.size() + 1);
return emitPutS(GV, B, TLI);
}
// Optimize specific format strings.
// printf("%c", chr) --> putchar(chr)
if (FormatStr == "%c" && CI->getNumArgOperands() > 1 &&
CI->getArgOperand(1)->getType()->isIntegerTy()) {
Value *Res = emitPutChar(CI->getArgOperand(1), B, TLI);
if (CI->use_empty() || !Res)
return Res;
return B.CreateIntCast(Res, CI->getType(), true);
}
CI->getArgOperand(1)->getType()->isIntegerTy())
return emitPutChar(CI->getArgOperand(1), B, TLI);
// printf("%s\n", str) --> puts(str)
if (FormatStr == "%s\n" && CI->getNumArgOperands() > 1 &&
CI->getArgOperand(1)->getType()->isPointerTy()) {
CI->getArgOperand(1)->getType()->isPointerTy())
return emitPutS(CI->getArgOperand(1), B, TLI);
}
return nullptr;
}