From 8a9193927a2661293a2afd5d1420faa2b0b8e6bf Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 29 Nov 2004 21:26:12 +0000
Subject: [PATCH] Allow hoisting loads of globals and alloca's in conditionals.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18363 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LICM.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index e9f2b330eef..c20e179f107 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -592,6 +592,12 @@ bool LICM::isSafeToExecuteUnconditionally(Instruction &Inst) {
   if (Inst.getParent() == CurLoop->getHeader())
     return true;
 
+  // It's always safe to load from a global or alloca.
+  if (isa<LoadInst>(Inst))
+    if (isa<AllocationInst>(Inst.getOperand(0)) ||
+        isa<GlobalVariable>(Inst.getOperand(0)))
+      return true;
+
   // Get the exit blocks for the current loop.
   std::vector<BasicBlock*> ExitBlocks;
   CurLoop->getExitBlocks(ExitBlocks);