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Do not optimise fprintf() calls if its return value is used.

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Differential Revision: http://llvm-reviews.chandlerc.com/D620

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179661 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2013-04-17 02:01:10 +00:00
parent 8afc8b7e63
commit c7ab4f99be
2 changed files with 21 additions and 9 deletions
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21
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@ -1518,6 +1518,12 @@ struct FPrintFOpt : public LibCallOptimization {
if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr)) if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
return 0; return 0;
// Do not do any of the following transformations if the fprintf return
// value is used, in general the fprintf return value is not compatible
// with fwrite(), fputc() or fputs().
if (!CI->use_empty())
return 0;
// fprintf(F, "foo") --> fwrite("foo", 3, 1, F) // fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
if (CI->getNumArgOperands() == 2) { if (CI->getNumArgOperands() == 2) {
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i) for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
@ -1527,11 +1533,10 @@ struct FPrintFOpt : public LibCallOptimization {
// These optimizations require DataLayout. // These optimizations require DataLayout.
if (!TD) return 0; if (!TD) return 0;
Value *NewCI = EmitFWrite(CI->getArgOperand(1), return EmitFWrite(CI->getArgOperand(1),
ConstantInt::get(TD->getIntPtrType(*Context), ConstantInt::get(TD->getIntPtrType(*Context),
FormatStr.size()), FormatStr.size()),
CI->getArgOperand(0), B, TD, TLI); CI->getArgOperand(0), B, TD, TLI);
return NewCI ? ConstantInt::get(CI->getType(), FormatStr.size()) : 0;
} }
// The remaining optimizations require the format string to be "%s" or "%c" // The remaining optimizations require the format string to be "%s" or "%c"
@ -1544,14 +1549,12 @@ struct FPrintFOpt : public LibCallOptimization {
if (FormatStr[1] == 'c') { if (FormatStr[1] == 'c') {
// fprintf(F, "%c", chr) --> fputc(chr, F) // fprintf(F, "%c", chr) --> fputc(chr, F)
if (!CI->getArgOperand(2)->getType()->isIntegerTy()) return 0; if (!CI->getArgOperand(2)->getType()->isIntegerTy()) return 0;
Value *NewCI = EmitFPutC(CI->getArgOperand(2), CI->getArgOperand(0), B, return EmitFPutC(CI->getArgOperand(2), CI->getArgOperand(0), B, TD, TLI);
TD, TLI);
return NewCI ? ConstantInt::get(CI->getType(), 1) : 0;
} }
if (FormatStr[1] == 's') { if (FormatStr[1] == 's') {
// fprintf(F, "%s", str) --> fputs(str, F) // fprintf(F, "%s", str) --> fputs(str, F)
if (!CI->getArgOperand(2)->getType()->isPointerTy() || !CI->use_empty()) if (!CI->getArgOperand(2)->getType()->isPointerTy())
return 0; return 0;
return EmitFPutS(CI->getArgOperand(2), CI->getArgOperand(0), B, TD, TLI); return EmitFPutS(CI->getArgOperand(2), CI->getArgOperand(0), B, TD, TLI);
} }

9
test/Transforms/InstCombine/fprintf-1.ll
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@ -78,3 +78,12 @@ define void @test_no_simplify2(%FILE* %fp, double %d) {
ret void ret void
; CHECK-NEXT: ret void ; CHECK-NEXT: ret void
} }
define i32 @test_no_simplify3(%FILE* %fp) {
; CHECK: @test_no_simplify3
%fmt = getelementptr [13 x i8]* @hello_world, i32 0, i32 0
%1 = call i32 (%FILE*, i8*, ...)* @fprintf(%FILE* %fp, i8* %fmt)
; CHECK-NEXT: call i32 (%FILE*, i8*, ...)* @fprintf(%FILE* %fp, i8* getelementptr inbounds ([13 x i8]* @hello_world, i32 0, i32 0))
ret i32 %1
; CHECK-NEXT: ret i32 %1
}