From 9750acc079409e52f6563636a112a9de50749b30 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Tue, 26 Apr 2011 17:41:02 +0000
Subject: [PATCH] Improve the bail-out predicate to really only kick in when
 phi translation fails.  We were bailing out in some cases that would cause us
 to miss GVN'ing some non-local cases away.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130206 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/GVN.cpp                 |  3 ++-
 test/Transforms/GVN/rle.ll                    | 23 +++++++++++++++++++
 .../SimplifyCFG/2006-08-03-Crash.ll           |  4 +---
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index 15db9ad70aa..7c11323ec8e 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1103,7 +1103,8 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
 
   // If we had a phi translation failure, we'll have a single entry which is a
   // clobber in the current block.  Reject this early.
-  if (Deps.size() == 1 && Deps[0].getResult().isClobber()) {
+  if (Deps.size() == 1 && Deps[0].getResult().isClobber() &&
+      Deps[0].getResult().getInst()->getParent() == LI->getParent()) {
     DEBUG(
       dbgs() << "GVN: non-local load ";
       WriteAsOperand(dbgs(), LI);
diff --git a/test/Transforms/GVN/rle.ll b/test/Transforms/GVN/rle.ll
index 42363d8bb2b..11e207cda07 100644
--- a/test/Transforms/GVN/rle.ll
+++ b/test/Transforms/GVN/rle.ll
@@ -570,4 +570,27 @@ entry:
 }
 
 
+; Cross block partial alias case.
+define i32 @load_load_partial_alias_cross_block(i8* %P) nounwind ssp {
+entry:
+  %xx = bitcast i8* %P to i32*
+  %x1 = load i32* %xx, align 4
+  %cmp = icmp eq i32 %x1, 127
+  br i1 %cmp, label %land.lhs.true, label %if.end
+
+land.lhs.true:                                    ; preds = %entry
+  %arrayidx4 = getelementptr inbounds i8* %P, i64 1
+  %tmp5 = load i8* %arrayidx4, align 1
+  %conv6 = zext i8 %tmp5 to i32
+  ret i32 %conv6
+
+if.end:
+  ret i32 52
+; CHECK: @load_load_partial_alias_cross_block
+; CHECK: land.lhs.true:
+; CHECK-NOT: load i8
+; CHECK: ret i32 %conv6
+}
+
+
 
diff --git a/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll b/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll
index 2c84c937ae3..70fbddfe33b 100644
--- a/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll
+++ b/test/Transforms/SimplifyCFG/2006-08-03-Crash.ll
@@ -1,7 +1,5 @@
-; RUN: opt < %s -gvn -simplifycfg \
-; RUN:   -disable-output
+; RUN: opt < %s -gvn -simplifycfg -disable-output
 ; PR867
-; END.
 
 target datalayout = "E-p:32:32"
 target triple = "powerpc-apple-darwin8"
-- 
2.34.1