From 4f833d435147f98329ae015140ca2b6ea530b717 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Thu, 11 Sep 2008 23:06:38 +0000
Subject: On 64-bit targets, change 32-bit getelementptr indices to be 64-bit
 getelementptr indices, inserting an explicit cast if necessary. This helps
 expose the sign-extension operation to other optimizations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56133 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/InstructionCombining.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

(limited to 'lib/Transforms')

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index f02a7108fd..1cb4fa2c21 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -9795,7 +9795,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
         }
       }
       // If we are using a wider index than needed for this platform, shrink it
-      // to what we need.  If the incoming value needs a cast instruction,
+      // to what we need.  If narrower, sign-extend it to what we need.
+      // If the incoming value needs a cast instruction,
       // insert it.  This explicit cast can make subsequent optimizations more
       // obvious.
       Value *Op = *i;
@@ -9809,6 +9810,16 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
           *i = Op;
           MadeChange = true;
         }
+      } else if (TD->getTypeSizeInBits(Op->getType()) < TD->getPointerSizeInBits()) {
+        if (Constant *C = dyn_cast<Constant>(Op)) {
+          *i = ConstantExpr::getSExt(C, TD->getIntPtrType());
+          MadeChange = true;
+        } else {
+          Op = InsertCastBefore(Instruction::SExt, Op, TD->getIntPtrType(),
+                                GEP);
+          *i = Op;
+          MadeChange = true;
+        }
       }
     }
   }
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