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Make strcpy_chk lower to strcpy if we have a safe size.

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llvm-svn: 94783
This commit is contained in:
Eric Christopher 2010-01-29 01:37:11 +00:00
parent 2112298100
commit f01379e6c2
2 changed files with 19 additions and 5 deletions
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12
lib/Transforms/Scalar/SimplifyLibCalls.cpp
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@ -1203,9 +1203,6 @@ struct MemMoveChkOpt : public LibCallOptimization {
struct StrCpyChkOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
@ -1217,8 +1214,13 @@ struct StrCpyChkOpt : public LibCallOptimization {
if (!SizeCI)
return 0;
// We don't have any length information, just lower to a plain strcpy.
if (SizeCI->isAllOnesValue())
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain strcpy. Otherwise we'll keep our
// strcpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (SizeCI->isAllOnesValue() ||
SizeCI->getZExtValue() >= GetStringLength(CI->getOperand(2)))
return EmitStrCpy(CI->getOperand(1), CI->getOperand(2), B);
return 0;

12
test/Transforms/SimplifyLibCalls/strcpy_chk.ll Normal file
View File

@ -0,0 +1,12 @@
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
@a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*> [#uses=1]
@.str = private constant [8 x i8] c"abcdefg\00" ; <[8 x i8]*> [#uses=1]
define i8* @foo() nounwind {
; CHECK: @foo
; CHECK-NEXT: call i8* @strcpy
%call = call i8* @__strcpy_chk(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i8* getelementptr inbounds ([8 x i8]* @.str, i32 0, i32 0), i32 60) ; <i8*> [#uses=1]
ret i8* %call
}
declare i8* @__strcpy_chk(i8*, i8*, i32) nounwind