[llvm-commits] [llvm] r122014 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyLibCalls.cpp test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll

[Dan Gohman]

Author: djg
Date: Thu Dec 16 19:09:43 2010
New Revision: 122014

URL: http://llvm.org/viewvc/llvm-project?rev=122014&view=rev
Log:
Revert r64460. strtol and friends cannot be marked readonly, even with
a null endptr argument, because they may write to errno.

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

Modified:
    llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
    llvm/trunk/test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp?rev=122014&r1=122013&r2=122014&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Thu Dec 16 19:09:43 2010
@@ -577,7 +577,8 @@
 
     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);
     }
 

Modified: llvm/trunk/test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll?rev=122014&r1=122013&r2=122014&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyLibCalls/2009-02-12-StrTo.ll Thu Dec 16 19:09:43 2010
@@ -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.