From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 10 Feb 2015 23:09:43 +0000 (+0000)
Subject: EarlyCSE: It isn't safe to CSE across synchronization boundaries
X-Git-Tag: llvmorg-3.7.0-rc1~12513
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7679300d9382e351dcecf2321c71e77723d1cae3;p=platform%2Fupstream%2Fllvm.git

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

This fixes PR22514.

llvm-svn: 228760
---

diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
index 9a9f965..862622f 100644
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -527,6 +527,9 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
       // Ignore volatile loads.
       if (MemInst.isVolatile()) {
         LastStore = nullptr;
+        // Don't CSE across synchronization boundaries.
+        if (Inst->mayWriteToMemory())
+          ++CurrentGeneration;
         continue;
       }
 
diff --git a/llvm/test/Transforms/EarlyCSE/basic.ll b/llvm/test/Transforms/EarlyCSE/basic.ll
index dee428c..5b78531 100644
--- a/llvm/test/Transforms/EarlyCSE/basic.ll
+++ b/llvm/test/Transforms/EarlyCSE/basic.ll
@@ -193,4 +193,10 @@ define void @test11(i32 *%P) {
   ; CHECK-NEXT: ret void
 }
 
-
+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
+}