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Fixing a corner-case bug in strchr and strrchr lib call optimizations where 

the input character is not converted to char before comparing with zero.

The patch was discussed in this thread:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130812/184069.html

llvm-svn: 188489
This commit is contained in:
Yunzhong Gao 2013-08-15 20:58:59 +00:00
parent 3d510b3db8
commit c0c2b16932
3 changed files with 24 additions and 2 deletions
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4
llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
View File

@ -477,7 +477,7 @@ struct StrChrOpt : public LibCallOptimization {
// Compute the offset, make sure to handle the case when we're searching for
// zero (a weird way to spell strlen).
size_t I = CharC->getSExtValue() == 0 ?
size_t I = (255 & CharC->getSExtValue()) == 0 ?
Str.size() : Str.find(CharC->getSExtValue());
if (I == StringRef::npos) // Didn't find the char. strchr returns null.
return Constant::getNullValue(CI->getType());
@ -513,7 +513,7 @@ struct StrRChrOpt : public LibCallOptimization {
}
// Compute the offset.
size_t I = CharC->getSExtValue() == 0 ?
size_t I = (255 & CharC->getSExtValue()) == 0 ?
Str.size() : Str.rfind(CharC->getSExtValue());
if (I == StringRef::npos) // Didn't find the char. Return null.
return Constant::getNullValue(CI->getType());

11
llvm/test/Transforms/InstCombine/strchr-1.ll
View File

@ -52,3 +52,14 @@ define void @test_simplify4(i32 %chr) {
store i8* %dst, i8** @chp
ret void
}
define void @test_simplify5() {
; CHECK: store i8* getelementptr inbounds ([14 x i8]* @hello, i32 0, i32 13)
; CHECK-NOT: call i8* @strchr
; CHECK: ret void
%src = getelementptr [14 x i8]* @hello, i32 0, i32 0
%dst = call i8* @strchr(i8* %src, i32 65280)
store i8* %dst, i8** @chp
ret void
}

11
llvm/test/Transforms/InstCombine/strrchr-1.ll
View File

@ -42,6 +42,17 @@ define void @test_simplify3() {
ret void
}
define void @test_simplify4() {
; CHECK: store i8* getelementptr inbounds ([14 x i8]* @hello, i32 0, i32 13)
; CHECK-NOT: call i8* @strrchr
; CHECK: ret void
%src = getelementptr [14 x i8]* @hello, i32 0, i32 0
%dst = call i8* @strrchr(i8* %src, i32 65280)
store i8* %dst, i8** @chp
ret void
}
define void @test_nosimplify1(i32 %chr) {
; CHECK-LABEL: @test_nosimplify1(
; CHECK: call i8* @strrchr