From: Chris Lattner <sabre@nondot.org>
Date: Wed, 14 Apr 2004 03:28:36 +0000 (+0000)
Subject: ADd a trivial instcombine: load null -> null
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=d9955aaa61adbcb7118d4d090d00a4c6a7bbadf1;p=oota-llvm.git

ADd a trivial instcombine: load null -> null


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12940 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index af85c5fdde9..fe13a6ba540 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2853,8 +2853,11 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
   Value *Op = LI.getOperand(0);
   if (LI.isVolatile()) return 0;
 
-  if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(Op))
-    Op = CPR->getValue();
+  if (Constant *C = dyn_cast<Constant>(Op))
+    if (C->isNullValue())  // load null -> 0
+      return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
+    else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C))
+      Op = CPR->getValue();
 
   // Instcombine load (constant global) into the value loaded...
   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))