commit 0a4fc46321681ea78265cb9415c242e84b45fe61
author Peter Collingbourne <peter@pcc.me.uk> Tue Nov 22 01:03:40 2016 +0000
committer Peter Collingbourne <peter@pcc.me.uk> Tue Nov 22 01:03:40 2016 +0000
tree f70d689b65adaeff96d5e0546ca33c2d8bfbbc4a
parent c4030a19379c88f899f343281f6eacd5caa0218f

Analysis: gep inbounds (gep inbounds (...)) is inbounds.

Differential Revision: https://reviews.llvm.org/D26441

llvm-svn: 287604

llvm/lib/Analysis/ConstantFolding.cpp

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 69e2e8a..500faed 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -773,6 +773,7 @@
                                   const DataLayout &DL,
                                   const TargetLibraryInfo *TLI) {
   const GEPOperator *InnermostGEP = GEP;
+  bool InBounds = GEP->isInBounds();
 
   Type *SrcElemTy = GEP->getSourceElementType();
   Type *ResElemTy = GEP->getResultElementType();
@@ -825,6 +826,7 @@
   // If this is a GEP of a GEP, fold it all into a single GEP.
   while (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
     InnermostGEP = GEP;
+    InBounds &= GEP->isInBounds();
 
     SmallVector<Value *, 4> NestedOps(GEP->op_begin() + 1, GEP->op_end());
 
@@ -946,8 +948,8 @@
     }
 
   // Create a GEP.
-  Constant *C = ConstantExpr::getGetElementPtr(
-      SrcElemTy, Ptr, NewIdxs, /*InBounds=*/false, InRangeIndex);
+  Constant *C = ConstantExpr::getGetElementPtr(SrcElemTy, Ptr, NewIdxs,
+                                               InBounds, InRangeIndex);
   assert(C->getType()->getPointerElementType() == Ty &&
          "Computed GetElementPtr has unexpected type!");