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Revert [InstCombine] sprintf(dest, "%s", str) -> memccpy(dest, str, 0, MAX) 

Seems to be slower than memcpy + strlen.

llvm-svn: 373335
This commit is contained in:
David Bolvansky 2019-10-01 13:19:04 +00:00
parent 1ce75045eb
commit 4037582d6b
3 changed files with 20 additions and 38 deletions
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41
llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
View File

@ -2415,11 +2415,9 @@ Value *LibCallSimplifier::optimizePrintF(CallInst *CI, IRBuilder<> &B) {
}
Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
Value *Dst = CI->getArgOperand(0);
Value *FmtStr = CI->getArgOperand(1);
// Check for a fixed format string.
StringRef FormatStr;
if (!getConstantStringInfo(FmtStr, FormatStr))
if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
return nullptr;
// If we just have a format string (nothing else crazy) transform it.
@ -2430,10 +2428,9 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
return nullptr; // we found a format specifier, bail out.
// sprintf(str, fmt) -> llvm.memcpy(align 1 str, align 1 fmt, strlen(fmt)+1)
B.CreateMemCpy(
Dst, 1, FmtStr, 1,
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
FormatStr.size() + 1)); // Copy the null byte.
B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1,
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
FormatStr.size() + 1)); // Copy the null byte.
return ConstantInt::get(CI->getType(), FormatStr.size());
}
@ -2443,14 +2440,13 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
CI->getNumArgOperands() < 3)
return nullptr;
Value *Str = CI->getArgOperand(2);
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!Str->getType()->isIntegerTy())
if (!CI->getArgOperand(2)->getType()->isIntegerTy())
return nullptr;
Value *V = B.CreateTrunc(Str, B.getInt8Ty(), "char");
Value *Ptr = castToCStr(Dst, B);
Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char");
Value *Ptr = castToCStr(CI->getArgOperand(0), B);
B.CreateStore(V, Ptr);
Ptr = B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul");
B.CreateStore(B.getInt8(0), Ptr);
@ -2459,30 +2455,17 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
}
if (FormatStr[1] == 's') {
if (!Str->getType()->isPointerTy())
return nullptr;
// sprintf(dest, "%s", str) -> memccpy(dest, str, 0, MAX)
if (CI->use_empty()) {
Value *S = (Dst->getType() == Str->getType())
? Str
: B.CreateBitCast(Str, Dst->getType());
unsigned SizeTyBitwidth =
DL.getIntPtrType(CI->getContext())->getPrimitiveSizeInBits();
Value *NewSize = ConstantInt::get(B.getIntNTy(SizeTyBitwidth),
APInt::getMaxValue(SizeTyBitwidth));
emitMemCCpy(Dst, S, B.getInt32('\0'), NewSize, B, TLI);
return Dst;
}
// sprintf(dest, "%s", str) -> llvm.memcpy(align 1 dest, align 1 str,
// strlen(str)+1)
Value *Len = emitStrLen(Str, B, DL, TLI);
if (!CI->getArgOperand(2)->getType()->isPointerTy())
return nullptr;
Value *Len = emitStrLen(CI->getArgOperand(2), B, DL, TLI);
if (!Len)
return nullptr;
Value *IncLen =
B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), "leninc");
B.CreateMemCpy(Dst, 1, Str, 1, IncLen);
B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(2), 1, IncLen);
// The sprintf result is the unincremented number of bytes in the string.
return B.CreateIntCast(Len, CI->getType(), false);

9
llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
View File

@ -1,4 +1,3 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
; PR7265
@ -10,14 +9,10 @@ target triple = "x86_64-unknown-linux-gnu"
@.str = private constant [3 x i8] c"%s\00"
define void @CopyEventArg(%union.anon* %ev) nounwind {
; CHECK-LABEL: @CopyEventArg(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = bitcast %union.anon* [[EV:%.*]] to i8*
; CHECK-NEXT: [[MEMCCPY:%.*]] = call i8* @memccpy(i8* undef, i8* [[TMP0]], i32 0, i64 -1)
; CHECK-NEXT: ret void
;
entry:
%call = call i32 (i8*, i8*, ...) @sprintf(i8* undef, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), %union.anon* %ev) nounwind
; CHECK: bitcast %union.anon* %ev to i8*
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64
ret void
}

8
llvm/test/Transforms/InstCombine/sprintf-1.ll
View File

@ -85,11 +85,15 @@ define void @test_simplify4(i8* %dst) {
define void @test_simplify5(i8* %dst, i8* %str) {
; CHECK-LABEL: @test_simplify5(
; CHECK-NEXT: [[MEMCCPY:%.*]] = call i8* @memccpy(i8* [[DST:%.*]], i8* [[STR:%.*]], i32 0, i32 -1)
; CHECK-NEXT: [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
; CHECK-NEXT: [[LENINC:%.*]] = add i32 [[STRLEN]], 1
; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
; CHECK-NEXT: ret void
;
; CHECK-IPRINTF-LABEL: @test_simplify5(
; CHECK-IPRINTF-NEXT: [[MEMCCPY:%.*]] = call i8* @memccpy(i8* [[DST:%.*]], i8* [[STR:%.*]], i32 0, i32 -1)
; CHECK-IPRINTF-NEXT: [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
; CHECK-IPRINTF-NEXT: [[LENINC:%.*]] = add i32 [[STRLEN]], 1
; CHECK-IPRINTF-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
; CHECK-IPRINTF-NEXT: ret void
;
%fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0