From: Peter Collingbourne <peter@pcc.me.uk>
Date: Tue, 22 Nov 2016 01:03:40 +0000 (+0000)
Subject: Analysis: gep inbounds (gep inbounds (...)) is inbounds.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d703e44ea8171cbc7cbad4d7d0a28c37bf46c985;p=llvm

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

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287604 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 69e2e8ad20f..500faed39b1 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -773,6 +773,7 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
                                   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 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
   // 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 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
     }
 
   // 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!");
 
diff --git a/test/Other/constant-fold-gep.ll b/test/Other/constant-fold-gep.ll
index 9d52f800bc2..77c43a200c0 100644
--- a/test/Other/constant-fold-gep.ll
+++ b/test/Other/constant-fold-gep.ll
@@ -106,9 +106,9 @@
 
 ; PLAIN: @Y = global [3 x { i32, i32 }]* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 2)
 ; PLAIN: @Z = global i32* getelementptr inbounds (i32, i32* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 0, i64 1, i32 0), i64 1)
-; OPT: @Y = local_unnamed_addr global [3 x { i32, i32 }]* getelementptr ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 2)
+; OPT: @Y = local_unnamed_addr global [3 x { i32, i32 }]* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 2)
 ; OPT: @Z = local_unnamed_addr global i32* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 0, i64 1, i32 1)
-; TO: @Y = local_unnamed_addr global [3 x { i32, i32 }]* getelementptr ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 2)
+; TO: @Y = local_unnamed_addr global [3 x { i32, i32 }]* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 2)
 ; TO: @Z = local_unnamed_addr global i32* getelementptr inbounds ([3 x { i32, i32 }], [3 x { i32, i32 }]* @ext, i64 0, i64 1, i32 1)
 
 @ext = external global [3 x { i32, i32 }]