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PR11061: Make simplifylibcalls fold strcmp("", x) correctly. 

While I'm here, fix the related issue with strncmp, add some actual tests for strcmp and strncmp, and start using StringRef::compare for constant folding instead of using strcmp/strncmp so that the optimized IR isn't dependent on the host's implementation of strcmp.

llvm-svn: 141227
This commit is contained in:
Eli Friedman 2011-10-05 22:27:16 +00:00
parent 267f323d28
commit 3e3aecbc2c
3 changed files with 140 additions and 55 deletions
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31
llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
View File

@ -338,16 +338,17 @@ struct StrCmpOpt : public LibCallOptimization {
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strcmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(),
strcmp(Str1.c_str(),Str2.c_str()));
StringRef(Str1).compare(Str2));
if (HasStr1 && Str1.empty()) // strcmp("", x) -> -*x
return B.CreateNeg(B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"),
CI->getType()));
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strcmp(P, "x") -> memcmp(P, "x", 2)
uint64_t Len1 = GetStringLength(Str1P);
@ -400,16 +401,20 @@ struct StrNCmpOpt : public LibCallOptimization {
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2) {
StringRef SubStr1 = StringRef(Str1).substr(0, Length);
StringRef SubStr2 = StringRef(Str2).substr(0, Length);
return ConstantInt::get(CI->getType(), SubStr1.compare(SubStr2));
}
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> -*x
return B.CreateNeg(B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"),
CI->getType()));
if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(),
strncmp(Str1.c_str(), Str2.c_str(), Length));
return 0;
}
};

73
llvm/test/Transforms/SimplifyLibCalls/StrCmp.ll
View File

@ -1,28 +1,65 @@
; Test that the StrCmpOptimizer works correctly
; RUN: opt < %s -simplify-libcalls -S | \
; RUN: not grep {call.*strcmp}
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
@hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1]
@hell = constant [5 x i8] c"hell\00" ; <[5 x i8]*> [#uses=1]
@bell = constant [5 x i8] c"bell\00" ; <[5 x i8]*> [#uses=1]
@null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
declare i32 @strcmp(i8*, i8*)
declare i32 @puts(i8*)
define i32 @main() {
%hello_p = getelementptr [6 x i8]* @hello, i32 0, i32 0 ; <i8*> [#uses=5]
%hell_p = getelementptr [5 x i8]* @hell, i32 0, i32 0 ; <i8*> [#uses=1]
%null_p = getelementptr [1 x i8]* @null, i32 0, i32 0 ; <i8*> [#uses=4]
%temp1 = call i32 @strcmp( i8* %hello_p, i8* %hello_p ) ; <i32> [#uses=1]
%temp2 = call i32 @strcmp( i8* %null_p, i8* %null_p ) ; <i32> [#uses=1]
%temp3 = call i32 @strcmp( i8* %hello_p, i8* %null_p ) ; <i32> [#uses=1]
%temp4 = call i32 @strcmp( i8* %null_p, i8* %hello_p ) ; <i32> [#uses=1]
%temp5 = call i32 @strcmp( i8* %hell_p, i8* %hello_p ) ; <i32> [#uses=1]
%rslt1 = add i32 %temp1, %temp2 ; <i32> [#uses=1]
%rslt2 = add i32 %rslt1, %temp3 ; <i32> [#uses=1]
%rslt3 = add i32 %rslt2, %temp4 ; <i32> [#uses=1]
%rslt4 = add i32 %rslt3, %temp5 ; <i32> [#uses=1]
ret i32 %rslt4
; strcmp("", x) -> -*x
define i32 @test1(i8* %str) {
%temp1 = call i32 @strcmp(i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0), i8* %str)
ret i32 %temp1
; CHECK: @test1
; CHECK: %strcmpload = load i8* %str
; CHECK: %1 = zext i8 %strcmpload to i32
; CHECK: %temp1 = sub i32 0, %1
; CHECK: ret i32 %temp1
}
; strcmp(x, "") -> *x
define i32 @test2(i8* %str) {
%temp1 = call i32 @strcmp(i8* %str, i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0))
ret i32 %temp1
; CHECK: @test2
; CHECK: %strcmpload = load i8* %str
; CHECK: %temp1 = zext i8 %strcmpload to i32
; CHECK: ret i32 %temp1
}
; strcmp(x, y) -> cnst
define i32 @test3() {
%temp1 = call i32 @strcmp(i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0))
ret i32 %temp1
; CHECK: @test3
; CHECK: ret i32 -1
}
define i32 @test4() {
%temp1 = call i32 @strcmp(i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0))
ret i32 %temp1
; CHECK: @test4
; CHECK: ret i32 1
}
; strcmp(x, y) -> memcmp(x, y, <known length>)
; (This transform is rather difficult to trigger in a useful manner)
define i32 @test5(i1 %b) {
%sel = select i1 %b, i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([5 x i8]* @bell, i32 0, i32 0)
%temp1 = call i32 @strcmp(i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0), i8* %sel)
ret i32 %temp1
; CHECK: @test5
; CHECK: %memcmp = call i32 @memcmp(i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0), i8* %sel, i32 5)
; CHECK: ret i32 %memcmp
}
; strcmp(x,x) -> 0
define i32 @test6(i8* %str) {
%temp1 = call i32 @strcmp(i8* %str, i8* %str)
ret i32 %temp1
; CHECK: @test6
; CHECK: ret i32 0
}

91
llvm/test/Transforms/SimplifyLibCalls/StrNCmp.ll
View File

@ -1,35 +1,78 @@
; Test that the StrNCmpOptimizer works correctly
; RUN: opt < %s -simplify-libcalls -S | \
; RUN: not grep {call.*strncmp}
; Test that the StrCmpOptimizer works correctly
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
target triple = "i386-apple-darwin9.0"
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
@hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1]
@hell = constant [5 x i8] c"hell\00" ; <[5 x i8]*> [#uses=1]
@bell = constant [5 x i8] c"bell\00" ; <[5 x i8]*> [#uses=1]
@null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
declare i32 @strncmp(i8*, i8*, i32)
declare i32 @puts(i8*)
define i32 @main() {
%hello_p = getelementptr [6 x i8]* @hello, i32 0, i32 0 ; <i8*> [#uses=5]
%hell_p = getelementptr [5 x i8]* @hell, i32 0, i32 0 ; <i8*> [#uses=1]
%null_p = getelementptr [1 x i8]* @null, i32 0, i32 0 ; <i8*> [#uses=4]
%temp1 = call i32 @strncmp( i8* %hello_p, i8* %hello_p, i32 5 ) ; <i32> [#uses=1]
%temp2 = call i32 @strncmp( i8* %null_p, i8* %null_p, i32 0 ) ; <i32> [#uses=1]
%temp3 = call i32 @strncmp( i8* %hello_p, i8* %null_p, i32 0 ) ; <i32> [#uses=1]
%temp4 = call i32 @strncmp( i8* %null_p, i8* %hello_p, i32 0 ) ; <i32> [#uses=1]
%temp5 = call i32 @strncmp( i8* %hell_p, i8* %hello_p, i32 4 ) ; <i32> [#uses=1]
%rslt1 = add i32 %temp1, %temp2 ; <i32> [#uses=1]
%rslt2 = add i32 %rslt1, %temp3 ; <i32> [#uses=1]
%rslt3 = add i32 %rslt2, %temp4 ; <i32> [#uses=1]
%rslt4 = add i32 %rslt3, %temp5 ; <i32> [#uses=1]
ret i32 %rslt4
; strcmp("", x) -> -*x
define i32 @test1(i8* %str) {
%temp1 = call i32 @strncmp(i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0), i8* %str, i32 10)
ret i32 %temp1
; CHECK: @test1
; CHECK: %strcmpload = load i8* %str
; CHECK: %1 = zext i8 %strcmpload to i32
; CHECK: %temp1 = sub i32 0, %1
; CHECK: ret i32 %temp1
}
define i32 @test1(i8* %P, i8* %Q) {
%cmp = call i32 @strncmp(i8* %P, i8* %Q, i32 1)
ret i32 %cmp
; strcmp(x, "") -> *x
define i32 @test2(i8* %str) {
%temp1 = call i32 @strncmp(i8* %str, i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0), i32 10)
ret i32 %temp1
; CHECK: @test2
; CHECK: %strcmpload = load i8* %str
; CHECK: %temp1 = zext i8 %strcmpload to i32
; CHECK: ret i32 %temp1
}
; strncmp(x, y, n) -> cnst
define i32 @test3() {
%temp1 = call i32 @strncmp(i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0), i32 10)
ret i32 %temp1
; CHECK: @test3
; CHECK: ret i32 -1
}
define i32 @test4() {
%temp1 = call i32 @strncmp(i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([1 x i8]* @null, i32 0, i32 0), i32 10)
ret i32 %temp1
; CHECK: @test4
; CHECK: ret i32 1
}
define i32 @test5() {
%temp1 = call i32 @strncmp(i8* getelementptr inbounds ([5 x i8]* @hell, i32 0, i32 0), i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0), i32 4)
ret i32 %temp1
; CHECK: @test5
; CHECK: ret i32 0
}
; strncmp(x,y,1) -> memcmp(x,y,1)
define i32 @test6(i8* %str1, i8* %str2) {
%temp1 = call i32 @strncmp(i8* %str1, i8* %str2, i32 1)
ret i32 %temp1
; CHECK: @test6
; CHECK: load i8*
; CHECK: load i8*
; CHECK: sub i32
}
; strncmp(x,y,0) -> 0
define i32 @test7(i8* %str1, i8* %str2) {
%temp1 = call i32 @strncmp(i8* %str1, i8* %str2, i32 0)
ret i32 %temp1
; CHECK: @test7
; CHECK: ret i32 0
}
; strncmp(x,x,n) -> 0
define i32 @test8(i8* %str, i32 %n) {
%temp1 = call i32 @strncmp(i8* %str, i8* %str, i32 %n)
ret i32 %temp1
; CHECK: @test8
; CHECK: ret i32 0
}