[llvm-testresults] buildbot failure in lab.llvm.org on phase1 - sanity

[llvmlab-buildmaster at lab.llvm.org]

The Buildbot has detected a new failure on builder phase1 - sanity while building llvm.
Full details are available at:
 http://lab.llvm.org:8013/builders/phase1%20-%20sanity/builds/13847

Buildbot URL: http://lab.llvm.org:8013/

Buildslave for this Build: macpro1

Build Reason: scheduler
Build Source Stamp: 194220
Blamelist: majnemer

BUILD FAILED: failed

sincerely,
 -The Buildbot


================================================================================

CHANGES:
Files:
 lib/IR/ConstantFold.cpp
 test/Transforms/GVN/pr17732.ll
On: http://10.1.1.2/svn/llvm-project
For: llvm
At: Thu 07 Nov 2013 14:20:46
Changed By: majnemer
Comments: IR: Do not canonicalize constant GEPs into an out-of-bounds array access

Summary:
Consider a GEP of:
i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, i32 0, i32 0, i64 0)

If we proceeded to GEP the aforementioned object by 8, would form a GEP of:
i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, i32 0, i32 0, i64 8)

Note that we would go through the first array member, causing an
out-of-bounds accesses.  This is problematic because we might get fooled
if we are trying to evaluate loads using this GEP, for example, based
off of an object with a constant initializer where the array is zero.

This fixes PR17732.

Reviewers: nicholas, chandlerc, void

Reviewed By: void

CC: llvm-commits, echristo, void, aemerson

Differential Revision: http://llvm-reviews.chandlerc.com/D2093Properties: 




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