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instcombine: Migrate strstr optimizations 

This patch migrates the strstr optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167682
This commit is contained in:
Meador Inge 2012-11-11 03:51:48 +00:00
parent 76fc1a479a
commit 56edbc9323
5 changed files with 166 additions and 148 deletions
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91
llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
View File

@ -99,94 +99,11 @@ static bool CallHasFloatingPointArgument(const CallInst *CI) {
return false;
}
/// IsOnlyUsedInEqualityComparison - Return true if it is only used in equality
/// comparisons with With.
static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
if (IC->isEquality() && IC->getOperand(1) == With)
continue;
// Unknown instruction.
return false;
}
return true;
}
//===----------------------------------------------------------------------===//
// String and Memory LibCall Optimizations
// Memory LibCall Optimizations
//===----------------------------------------------------------------------===//
namespace {
//===---------------------------------------===//
// 'strstr' Optimizations
struct StrStrOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
!FT->getReturnType()->isPointerTy())
return 0;
// fold strstr(x, x) -> x.
if (CI->getArgOperand(0) == CI->getArgOperand(1))
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
if (TD && IsOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {
Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, TD, TLI);
if (!StrLen)
return 0;
Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),
StrLen, B, TD, TLI);
if (!StrNCmp)
return 0;
for (Value::use_iterator UI = CI->use_begin(), UE = CI->use_end();
UI != UE; ) {
ICmpInst *Old = cast<ICmpInst>(*UI++);
Value *Cmp = B.CreateICmp(Old->getPredicate(), StrNCmp,
ConstantInt::getNullValue(StrNCmp->getType()),
"cmp");
Old->replaceAllUsesWith(Cmp);
Old->eraseFromParent();
}
return CI;
}
// See if either input string is a constant string.
StringRef SearchStr, ToFindStr;
bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);
bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);
// fold strstr(x, "") -> x.
if (HasStr2 && ToFindStr.empty())
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// If both strings are known, constant fold it.
if (HasStr1 && HasStr2) {
std::string::size_type Offset = SearchStr.find(ToFindStr);
if (Offset == StringRef::npos) // strstr("foo", "bar") -> null
return Constant::getNullValue(CI->getType());
// strstr("abcd", "bc") -> gep((char*)"abcd", 1)
Value *Result = CastToCStr(CI->getArgOperand(0), B);
Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");
return B.CreateBitCast(Result, CI->getType());
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1) {
Value *StrChr= EmitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TD, TLI);
return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : 0;
}
return 0;
}
};
//===---------------------------------------===//
// 'memcmp' Optimizations
@ -969,8 +886,7 @@ namespace {
TargetLibraryInfo *TLI;
StringMap<LibCallOptimization*> Optimizations;
// String and Memory LibCall Optimizations
StrStrOpt StrStr;
// Memory LibCall Optimizations
MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
// Math Library Optimizations
CosOpt Cos; PowOpt Pow; Exp2Opt Exp2;
@ -1037,8 +953,7 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
/// Optimizations - Populate the Optimizations map with all the optimizations
/// we know.
void SimplifyLibCalls::InitOptimizations() {
// String and Memory LibCall Optimizations
Optimizations["strstr"] = &StrStr;
// Memory LibCall Optimizations
Optimizations["memcmp"] = &MemCmp;
AddOpt(LibFunc::memcpy, &MemCpy);
Optimizations["memmove"] = &MemMove;

80
llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
View File

@ -86,6 +86,20 @@ static bool isOnlyUsedInZeroEqualityComparison(Value *V) {
return true;
}
/// isOnlyUsedInEqualityComparison - Return true if it is only used in equality
/// comparisons with With.
static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
if (IC->isEquality() && IC->getOperand(1) == With)
continue;
// Unknown instruction.
return false;
}
return true;
}
//===----------------------------------------------------------------------===//
// Fortified Library Call Optimizations
//===----------------------------------------------------------------------===//
@ -836,6 +850,70 @@ struct StrCSpnOpt : public LibCallOptimization {
}
};
struct StrStrOpt : public LibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
!FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isPointerTy() ||
!FT->getReturnType()->isPointerTy())
return 0;
// fold strstr(x, x) -> x.
if (CI->getArgOperand(0) == CI->getArgOperand(1))
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
if (TD && isOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {
Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, TD, TLI);
if (!StrLen)
return 0;
Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),
StrLen, B, TD, TLI);
if (!StrNCmp)
return 0;
for (Value::use_iterator UI = CI->use_begin(), UE = CI->use_end();
UI != UE; ) {
ICmpInst *Old = cast<ICmpInst>(*UI++);
Value *Cmp = B.CreateICmp(Old->getPredicate(), StrNCmp,
ConstantInt::getNullValue(StrNCmp->getType()),
"cmp");
LCS->replaceAllUsesWith(Old, Cmp);
}
return CI;
}
// See if either input string is a constant string.
StringRef SearchStr, ToFindStr;
bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);
bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);
// fold strstr(x, "") -> x.
if (HasStr2 && ToFindStr.empty())
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// If both strings are known, constant fold it.
if (HasStr1 && HasStr2) {
std::string::size_type Offset = SearchStr.find(ToFindStr);
if (Offset == StringRef::npos) // strstr("foo", "bar") -> null
return Constant::getNullValue(CI->getType());
// strstr("abcd", "bc") -> gep((char*)"abcd", 1)
Value *Result = CastToCStr(CI->getArgOperand(0), B);
Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");
return B.CreateBitCast(Result, CI->getType());
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1) {
Value *StrChr= EmitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TD, TLI);
return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : 0;
}
return 0;
}
};
} // End anonymous namespace.
namespace llvm {
@ -869,6 +947,7 @@ class LibCallSimplifierImpl {
StrToOpt StrTo;
StrSpnOpt StrSpn;
StrCSpnOpt StrCSpn;
StrStrOpt StrStr;
void initOptimizations();
void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@ -914,6 +993,7 @@ void LibCallSimplifierImpl::initOptimizations() {
addOpt(LibFunc::strtoull, &StrTo);
addOpt(LibFunc::strspn, &StrSpn);
addOpt(LibFunc::strcspn, &StrCSpn);
addOpt(LibFunc::strstr, &StrStr);
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

65
llvm/test/Transforms/InstCombine/strstr-1.ll Normal file
View File

@ -0,0 +1,65 @@
; Test that the strstr library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
@.str = private constant [1 x i8] zeroinitializer
@.str1 = private constant [2 x i8] c"a\00"
@.str2 = private constant [6 x i8] c"abcde\00"
@.str3 = private constant [4 x i8] c"bcd\00"
declare i8* @strstr(i8*, i8*)
; Check strstr(str, "") -> str.
define i8* @test_simplify1(i8* %str) {
; CHECK: @test_simplify1
%pat = getelementptr inbounds [1 x i8]* @.str, i32 0, i32 0
%ret = call i8* @strstr(i8* %str, i8* %pat)
ret i8* %ret
; CHECK-NEXT: ret i8* %str
}
; Check strstr(str, "a") -> strchr(str, 'a').
define i8* @test_simplify2(i8* %str) {
; CHECK: @test_simplify2
%pat = getelementptr inbounds [2 x i8]* @.str1, i32 0, i32 0
%ret = call i8* @strstr(i8* %str, i8* %pat)
ret i8* %ret
; CHECK-NEXT: @strchr(i8* %str, i32 97)
}
; Check strstr("abcde", "bcd") -> "abcde" + 1.
define i8* @test_simplify3() {
; CHECK: @test_simplify3
%str = getelementptr inbounds [6 x i8]* @.str2, i32 0, i32 0
%pat = getelementptr inbounds [4 x i8]* @.str3, i32 0, i32 0
%ret = call i8* @strstr(i8* %str, i8* %pat)
ret i8* %ret
; CHECK-NEXT: getelementptr inbounds ([6 x i8]* @.str2, i64 0, i64 1)
}
; Check strstr(str, str) -> str.
define i8* @test_simplify4(i8* %str) {
; CHECK: @test_simplify4
%ret = call i8* @strstr(i8* %str, i8* %str)
ret i8* %ret
; CHECK-NEXT: ret i8* %str
}
; Check strstr(str, pat) == str -> strncmp(str, pat, strlen(str)) == 0.
define i1 @test_simplify5(i8* %str, i8* %pat) {
; CHECK: @test_simplify5
%ret = call i8* @strstr(i8* %str, i8* %pat)
%cmp = icmp eq i8* %ret, %str
ret i1 %cmp
; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %pat)
; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %str, i8* %pat, {{i[0-9]+}} [[LEN]])
; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0
; CHECK: ret i1
}

18
llvm/test/Transforms/InstCombine/strstr-2.ll Normal file
View File

@ -0,0 +1,18 @@
; Test that the strstr library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
@null = private constant [1 x i8] zeroinitializer
declare i8 @strstr(i8*, i8*)
define i8 @test_no_simplify1(i8* %str) {
; CHECK: @test_no_simplify1
%pat = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0
%ret = call i8 @strstr(i8* %str, i8* %pat)
; CHECK-NEXT: call i8 @strstr
ret i8 %ret
; CHECK-NEXT: ret i8 %ret
}

60
llvm/test/Transforms/SimplifyLibCalls/StrStr.ll
View File

@ -1,60 +0,0 @@
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
; PR5783
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"
@.str = private constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
@.str1 = private constant [2 x i8] c"a\00" ; <[2 x i8]*> [#uses=1]
@.str2 = private constant [6 x i8] c"abcde\00" ; <[6 x i8]*> [#uses=1]
@.str3 = private constant [4 x i8] c"bcd\00" ; <[4 x i8]*> [#uses=1]
define i8* @test1(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([1 x i8]* @.str, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, "") -> P
; CHECK: @test1
; CHECK: ret i8* %P
}
declare i8* @strstr(i8*, i8* nocapture) nounwind readonly
define i8* @test2(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([2 x i8]* @.str1, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, "a") -> strchr(P, 'a')
; CHECK: @test2
; CHECK: @strchr(i8* %P, i32 97)
}
define i8* @test3(i8* nocapture %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* getelementptr inbounds ([6 x i8]* @.str2, i32 0, i32 0), i8* getelementptr inbounds ([4 x i8]* @.str3, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr("abcde", "bcd") -> "abcde"+1
; CHECK: @test3
; CHECK: getelementptr inbounds ([6 x i8]* @.str2, i32 0, i64 1)
}
define i8* @test4(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* %P) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, P) -> P
; CHECK: @test4
; CHECK: ret i8* %P
}
define i1 @test5(i8* %P, i8* %Q) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* %Q) nounwind ; <i8*> [#uses=1]
%cmp = icmp eq i8* %call, %P
ret i1 %cmp
; CHECK: @test5
; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %Q)
; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %P, i8* %Q, {{i[0-9]+}} [[LEN]])
; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0
; CHECK: ret i1
}