instcombine: Migrate strncpy optimizations

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167102 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Meador Inge 2012-10-31 03:33:00 +00:00
parent 5b2c4dc5f8
commit a0885fb882
6 changed files with 175 additions and 90 deletions

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@ -134,56 +134,6 @@ static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
namespace { namespace {
//===---------------------------------------===//
// 'strncpy' Optimizations
struct StrNCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != B.getInt8PtrTy() ||
!FT->getParamType(2)->isIntegerTy())
return 0;
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *LenOp = CI->getArgOperand(2);
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen == 0) return 0;
--SrcLen;
if (SrcLen == 0) {
// strncpy(x, "", y) -> memset(x, '\0', y, 1)
B.CreateMemSet(Dst, B.getInt8('\0'), LenOp, 1);
return Dst;
}
uint64_t Len;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(LenOp))
Len = LengthArg->getZExtValue();
else
return 0;
if (Len == 0) return Dst; // strncpy(x, y, 0) -> x
// These optimizations require DataLayout.
if (!TD) return 0;
// Let strncpy handle the zero padding
if (Len > SrcLen+1) return 0;
Type *PT = FT->getParamType(0);
// strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant]
B.CreateMemCpy(Dst, Src,
ConstantInt::get(TD->getIntPtrType(PT), Len), 1);
return Dst;
}
};
//===---------------------------------------===// //===---------------------------------------===//
// 'strlen' Optimizations // 'strlen' Optimizations
@ -1196,7 +1146,6 @@ namespace {
StringMap<LibCallOptimization*> Optimizations; StringMap<LibCallOptimization*> Optimizations;
// String and Memory LibCall Optimizations // String and Memory LibCall Optimizations
StrNCpyOpt StrNCpy;
StrLenOpt StrLen; StrPBrkOpt StrPBrk; StrLenOpt StrLen; StrPBrkOpt StrPBrk;
StrToOpt StrTo; StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr; StrToOpt StrTo; StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr;
MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet; MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
@ -1266,7 +1215,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
/// we know. /// we know.
void SimplifyLibCalls::InitOptimizations() { void SimplifyLibCalls::InitOptimizations() {
// String and Memory LibCall Optimizations // String and Memory LibCall Optimizations
Optimizations["strncpy"] = &StrNCpy;
Optimizations["strlen"] = &StrLen; Optimizations["strlen"] = &StrLen;
Optimizations["strpbrk"] = &StrPBrk; Optimizations["strpbrk"] = &StrPBrk;
Optimizations["strtol"] = &StrTo; Optimizations["strtol"] = &StrTo;

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@ -628,6 +628,53 @@ struct StpCpyOpt: public LibCallOptimization {
} }
}; };
struct StrNCpyOpt : public LibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != B.getInt8PtrTy() ||
!FT->getParamType(2)->isIntegerTy())
return 0;
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *LenOp = CI->getArgOperand(2);
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen == 0) return 0;
--SrcLen;
if (SrcLen == 0) {
// strncpy(x, "", y) -> memset(x, '\0', y, 1)
B.CreateMemSet(Dst, B.getInt8('\0'), LenOp, 1);
return Dst;
}
uint64_t Len;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(LenOp))
Len = LengthArg->getZExtValue();
else
return 0;
if (Len == 0) return Dst; // strncpy(x, y, 0) -> x
// These optimizations require DataLayout.
if (!TD) return 0;
// Let strncpy handle the zero padding
if (Len > SrcLen+1) return 0;
Type *PT = FT->getParamType(0);
// strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant]
B.CreateMemCpy(Dst, Src,
ConstantInt::get(TD->getIntPtrType(PT), Len), 1);
return Dst;
}
};
} // End anonymous namespace. } // End anonymous namespace.
namespace llvm { namespace llvm {
@ -654,6 +701,7 @@ class LibCallSimplifierImpl {
StrNCmpOpt StrNCmp; StrNCmpOpt StrNCmp;
StrCpyOpt StrCpy; StrCpyOpt StrCpy;
StpCpyOpt StpCpy; StpCpyOpt StpCpy;
StrNCpyOpt StrNCpy;
void initOptimizations(); void initOptimizations();
public: public:
@ -684,6 +732,7 @@ void LibCallSimplifierImpl::initOptimizations() {
Optimizations["strncmp"] = &StrNCmp; Optimizations["strncmp"] = &StrNCmp;
Optimizations["strcpy"] = &StrCpy; Optimizations["strcpy"] = &StrCpy;
Optimizations["stpcpy"] = &StpCpy; Optimizations["stpcpy"] = &StpCpy;
Optimizations["strncpy"] = &StrNCpy;
} }
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) { Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

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@ -0,0 +1,95 @@
; Test that the strncpy library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -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"
@null = constant [1 x i8] zeroinitializer
@null_hello = constant [7 x i8] c"\00hello\00"
@a = common global [32 x i8] zeroinitializer, align 1
@b = common global [32 x i8] zeroinitializer, align 1
declare i8* @strncpy(i8*, i8*, i32)
declare i32 @puts(i8*)
; Check a bunch of strncpy invocations together.
define i32 @test_simplify1() {
; CHECK: @test_simplify1
; CHECK-NOT: call i8* @strncpy
; CHECK: call i32 @puts
%target = alloca [1024 x i8]
%arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0
store i8 0, i8* %arg1
%arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0
%rslt1 = call i8* @strncpy(i8* %arg1, i8* %arg2, i32 6)
%arg3 = getelementptr [1 x i8]* @null, i32 0, i32 0
%rslt2 = call i8* @strncpy(i8* %rslt1, i8* %arg3, i32 42)
%arg4 = getelementptr [7 x i8]* @null_hello, i32 0, i32 0
%rslt3 = call i8* @strncpy(i8* %rslt2, i8* %arg4, i32 42)
call i32 @puts( i8* %rslt3 )
ret i32 0
}
; Check strncpy(x, "", y) -> memset(x, '\0', y, 1).
define void @test_simplify2() {
; CHECK: @test_simplify2
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [1 x i8]* @null, i32 0, i32 0
call i8* @strncpy(i8* %dst, i8* %src, i32 32)
; CHECK: call void @llvm.memset.p0i8.i32
ret void
}
; Check strncpy(x, y, 0) -> x.
define i8* @test_simplify3() {
; CHECK: @test_simplify3
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [6 x i8]* @hello, i32 0, i32 0
%ret = call i8* @strncpy(i8* %dst, i8* %src, i32 0)
ret i8* %ret
; CHECK: ret i8* getelementptr inbounds ([32 x i8]* @a, i32 0, i32 0)
}
; Check strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant].
define void @test_simplify4() {
; CHECK: @test_simplify4
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [6 x i8]* @hello, i32 0, i32 0
call i8* @strncpy(i8* %dst, i8* %src, i32 6)
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i32
ret void
}
; Check cases that shouldn't be simplified.
define void @test_no_simplify1() {
; CHECK: @test_no_simplify1
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [32 x i8]* @b, i32 0, i32 0
call i8* @strncpy(i8* %dst, i8* %src, i32 32)
; CHECK: call i8* @strncpy
ret void
}
define void @test_no_simplify2() {
; CHECK: @test_no_simplify2
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [6 x i8]* @hello, i32 0, i32 0
call i8* @strncpy(i8* %dst, i8* %src, i32 8)
; CHECK: call i8* @strncpy
ret void
}

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@ -0,0 +1,22 @@
; Test that the strncpy library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -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"
@a = common global [32 x i8] zeroinitializer, align 1
declare i16* @strncpy(i8*, i8*, i32)
; Check that 'strncpy' functions with the wrong prototype aren't simplified.
define void @test_no_simplify1() {
; CHECK: @test_no_simplify1
%dst = getelementptr [32 x i8]* @a, i32 0, i32 0
%src = getelementptr [6 x i8]* @hello, i32 0, i32 0
call i16* @strncpy(i8* %dst, i8* %src, i32 6)
; CHECK: call i16* @strncpy
ret void
}

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@ -7,27 +7,27 @@ target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f3
@a = common global [60 x i8] zeroinitializer, align 1 @a = common global [60 x i8] zeroinitializer, align 1
@b = common global [60 x i8] zeroinitializer, align 1 @b = common global [60 x i8] zeroinitializer, align 1
@.str = private constant [8 x i8] c"abcdefg\00" @.str = private constant [12 x i8] c"abcdefghijk\00"
; Check cases where dstlen >= len ; Check cases where dstlen >= len
define void @test_simplify1() { define void @test_simplify1() {
; CHECK: @test_simplify1 ; CHECK: @test_simplify1
%dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0 %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
%src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0 %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
; CHECK-NEXT: call i8* @strncpy ; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32
call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 60) call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 12, i32 60)
ret void ret void
} }
define void @test_simplify2() { define void @test_simplify2() {
; CHECK: @test_simplify2 ; CHECK: @test_simplify2
%dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0 %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
%src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0 %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
; CHECK-NEXT: call i8* @strncpy ; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32
call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 8) call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 12, i32 12)
ret void ret void
} }
@ -37,7 +37,7 @@ define void @test_simplify3() {
%src = getelementptr inbounds [60 x i8]* @b, i32 0, i32 0 %src = getelementptr inbounds [60 x i8]* @b, i32 0, i32 0
; CHECK-NEXT: call i8* @strncpy ; CHECK-NEXT: call i8* @strncpy
call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 60) call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 12, i32 60)
ret void ret void
} }
@ -46,7 +46,7 @@ define void @test_simplify3() {
define void @test_no_simplify1() { define void @test_no_simplify1() {
; CHECK: @test_no_simplify1 ; CHECK: @test_no_simplify1
%dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0 %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
%src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0 %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
; CHECK-NEXT: call i8* @__strncpy_chk ; CHECK-NEXT: call i8* @__strncpy_chk
call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 4) call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 4)

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@ -1,29 +0,0 @@
; Test that the StrNCpyOptimizer works correctly
; RUN: opt < %s -simplify-libcalls -S | \
; RUN: not grep "call.*strncpy"
; This transformation requires the pointer size, as it assumes that size_t is
; the size of a pointer.
target datalayout = "-p:64:64:64"
@hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1]
@null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
@null_hello = constant [7 x i8] c"\00hello\00" ; <[7 x i8]*> [#uses=1]
declare i8* @strncpy(i8*, i8*, i32)
declare i32 @puts(i8*)
define i32 @main() {
%target = alloca [1024 x i8] ; <[1024 x i8]*> [#uses=1]
%arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0 ; <i8*> [#uses=2]
store i8 0, i8* %arg1
%arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt1 = call i8* @strncpy( i8* %arg1, i8* %arg2, i32 6 ) ; <i8*> [#uses=1]
%arg3 = getelementptr [1 x i8]* @null, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt2 = call i8* @strncpy( i8* %rslt1, i8* %arg3, i32 42 ) ; <i8*> [#uses=1]
%arg4 = getelementptr [7 x i8]* @null_hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt3 = call i8* @strncpy( i8* %rslt2, i8* %arg4, i32 42 ) ; <i8*> [#uses=1]
call i32 @puts( i8* %rslt3 ) ; <i32>:1 [#uses=0]
ret i32 0
}