From 98a42b2fc39f3fc46905fb98078cce4ce4e0a827 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 22 May 2011 07:15:13 +0000
Subject: [PATCH] fix PR9856, an incorrectly conservative assertion: a global
 can be "stored once" even if its address is compared.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131849 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/GlobalOpt.cpp   |  6 +++---
 test/Transforms/GlobalOpt/crash.ll | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index ded58aca75f..9d98bb156b4 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -799,7 +799,8 @@ static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) {
       // If we get here we could have other crazy uses that are transitively
       // loaded.
       assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
-              isa<ConstantExpr>(GlobalUser)) && "Only expect load and stores!");
+              isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser)) &&
+             "Only expect load and stores!");
     }
   }
 
@@ -1589,8 +1590,7 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
       GV->getInitializer()->isNullValue()) {
     if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) {
       if (GV->getInitializer()->getType() != SOVC->getType())
-        SOVC =
-         ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
+        SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
 
       // Optimize away any trapping uses of the loaded value.
       if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
diff --git a/test/Transforms/GlobalOpt/crash.ll b/test/Transforms/GlobalOpt/crash.ll
index 9da5a5e3c93..366a874f735 100644
--- a/test/Transforms/GlobalOpt/crash.ll
+++ b/test/Transforms/GlobalOpt/crash.ll
@@ -64,3 +64,17 @@ define void @memset_with_strange_user() ssp {
   ret void
 }
 declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
+
+
+; PR9856
+@g_52 = internal global i32** null, align 8
+@g_90 = external global i32*, align 8
+
+define void @icmp_user_of_stored_once() nounwind ssp {
+entry:
+  %tmp4 = load i32*** @g_52, align 8
+  store i32** @g_90, i32*** @g_52
+  %cmp17 = icmp ne i32*** undef, @g_52
+  ret void
+}
+