From: Hans Wennborg <hans@hanshq.net>
Date: Wed, 11 Feb 2015 02:23:00 +0000 (+0000)
Subject: Merging r228760 and r228761:
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d7210365f520abd9b34e158acf460899997016e6;p=llvm

Merging r228760 and r228761:

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r228760 | majnemer | 2015-02-10 15:09:43 -0800 (Tue, 10 Feb 2015) | 3 lines

EarlyCSE: It isn't safe to CSE across synchronization boundaries

This fixes PR22514.
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r228761 | majnemer | 2015-02-10 15:11:02 -0800 (Tue, 10 Feb 2015) | 1 line

EarlyCSE: Add check lines for test added in r228760
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_36@228790 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/EarlyCSE.cpp b/lib/Transforms/Scalar/EarlyCSE.cpp
index 394b0d3de7b..969b9a8f8df 100644
--- a/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -480,6 +480,9 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
       // Ignore volatile loads.
       if (!LI->isSimple()) {
         LastStore = nullptr;
+        // Don't CSE across synchronization boundaries.
+        if (Inst->mayWriteToMemory())
+          ++CurrentGeneration;
         continue;
       }
 
diff --git a/test/Transforms/EarlyCSE/basic.ll b/test/Transforms/EarlyCSE/basic.ll
index 155d36f60e2..3ec8831def1 100644
--- a/test/Transforms/EarlyCSE/basic.ll
+++ b/test/Transforms/EarlyCSE/basic.ll
@@ -192,4 +192,13 @@ define void @test11(i32 *%P) {
   ; CHECK-NEXT: ret void
 }
 
-
+; CHECK-LABEL: @test12(
+define i32 @test12(i1 %B, i32* %P1, i32* %P2) {
+  %load0 = load i32* %P1
+  %1 = load atomic i32* %P2 seq_cst, align 4
+  %load1 = load i32* %P1
+  %sel = select i1 %B, i32 %load0, i32 %load1
+  ret i32 %sel
+  ; CHECK: load i32* %P1
+  ; CHECK: load i32* %P1
+}