MemoryDependenceAnalysis: Don't miscompile atomics

r216771 introduced a change to MemoryDependenceAnalysis that allowed it
to reason about acquire/release operations.  However, this change does
not ensure that the acquire/release operations pair.  Unfortunately,
this leads to miscompiles as we won't see an acquire load as properly
memory effecting.  This largely reverts r216771.

This fixes PR22708.

llvm-svn: 232889

1 files changed, 0 insertions, 46 deletions

diff --git a/llvm/test/Transforms/DeadStoreElimination/atomic.ll b/llvm/test/Transforms/DeadStoreElimination/atomic.ll
index 4d2cb37f258..79beee803e4 100644
--- a/llvm/test/Transforms/DeadStoreElimination/atomic.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/atomic.ll
@@ -23,28 +23,6 @@ define void @test1() {
   ret void
 }
 
-; DSE across seq_cst load (allowed)
-define i32 @test2() {
-; CHECK-LABEL: test2
-; CHECK-NOT: store i32 0
-; CHECK: store i32 1
-  store i32 0, i32* @x
-  %x = load atomic i32, i32* @y seq_cst, align 4
-  store i32 1, i32* @x
-  ret i32 %x
-}
-
-; DSE across seq_cst store (allowed)
-define void @test3() {
-; CHECK-LABEL: test3
-; CHECK-NOT: store i32 0
-; CHECK: store atomic i32 2
-  store i32 0, i32* @x
-  store atomic i32 2, i32* @y seq_cst, align 4
-  store i32 1, i32* @x
-  ret void
-}
-
 ; DSE remove unordered store (allowed)
 define void @test4() {
 ; CHECK-LABEL: test4
@@ -141,30 +119,6 @@ define void @test12() {
   ret void
 }
 
-; DSE is allowed across a pair of an atomic read and then write.
-define i32 @test13() {
-; CHECK-LABEL: test13
-; CHECK-NOT: store i32 0
-; CHECK: store i32 1
-  store i32 0, i32* @x
-  %x = load atomic i32, i32* @y seq_cst, align 4
-  store atomic i32 %x, i32* @y seq_cst, align 4
-  store i32 1, i32* @x
-  ret i32 %x
-}
-
-; Same if it is acquire-release instead of seq_cst/seq_cst
-define i32 @test14() {
-; CHECK-LABEL: test14
-; CHECK-NOT: store i32 0
-; CHECK: store i32 1
-  store i32 0, i32* @x
-  %x = load atomic i32, i32* @y acquire, align 4
-  store atomic i32 %x, i32* @y release, align 4
-  store i32 1, i32* @x
-  ret i32 %x
-}
-
 ; But DSE is not allowed across a release-acquire pair.
 define i32 @test15() {
 ; CHECK-LABEL: test15