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Revert r64460. strtol and friends cannot be marked readonly, even with

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a null endptr argument, because they may write to errno.

This fixes a seflhost miscompile observed on Linux targets when TBAA
was enabled.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122014 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-12-17 01:09:43 +00:00
parent 2d8e3e741f
commit c32046e6ea
2 changed files with 3 additions and 2 deletions
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3
lib/Transforms/Scalar/SimplifyLibCalls.cpp
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@ -577,7 +577,8 @@ struct StrToOpt : public LibCallOptimization {
Value *EndPtr = CI->getArgOperand(1);
if (isa<ConstantPointerNull>(EndPtr)) {
CI->setOnlyReadsMemory();
// With a null EndPtr, this function won't capture the main argument.
// It would be readonly too, except that it still may write to errno.
CI->addAttribute(1, Attribute::NoCapture);
}

2
test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll
View File

@ -1,7 +1,7 @@
; RUN: opt < %s -simplify-libcalls -S > %t
; RUN: grep nocapture %t | count 2
; RUN: grep null %t | grep nocapture | count 1
; RUN: grep null %t | grep call | grep readonly | count 1
; RUN: grep null %t | grep call | not grep readonly
; Test that we add nocapture to the declaration, and to the second call only.