[PATCH] D61863: Prefer locked stack op over mfence for seq_cst stores

[Philip Reames via Phabricator via llvm-commits]

reames updated this revision to Diff 199291.
reames added a comment.

Fix a stale comment.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61863/new/

https://reviews.llvm.org/D61863

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/atomic-load-store-wide.ll
  test/CodeGen/X86/atomic-non-integer.ll


Index: test/CodeGen/X86/atomic-non-integer.ll
===================================================================
--- test/CodeGen/X86/atomic-non-integer.ll
+++ test/CodeGen/X86/atomic-non-integer.ll
@@ -710,7 +710,7 @@
 ; X86-SSE2-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-SSE2-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
 ; X86-SSE2-NEXT:    movlps %xmm0, (%eax)
-; X86-SSE2-NEXT:    mfence
+; X86-SSE2-NEXT:    lock orl $0, (%esp)
 ; X86-SSE2-NEXT:    retl
 ;
 ; X86-AVX-LABEL: store_double_seq_cst:
@@ -718,7 +718,7 @@
 ; X86-AVX-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-AVX-NEXT:    vmovsd {{.*#+}} xmm0 = mem[0],zero
 ; X86-AVX-NEXT:    vmovlps %xmm0, (%eax)
-; X86-AVX-NEXT:    mfence
+; X86-AVX-NEXT:    lock orl $0, (%esp)
 ; X86-AVX-NEXT:    retl
 ;
 ; X86-NOSSE-LABEL: store_double_seq_cst:
Index: test/CodeGen/X86/atomic-load-store-wide.ll
===================================================================
--- test/CodeGen/X86/atomic-load-store-wide.ll
+++ test/CodeGen/X86/atomic-load-store-wide.ll
@@ -11,7 +11,7 @@
 ; SSE42-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; SSE42-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
 ; SSE42-NEXT:    movlps %xmm0, (%eax)
-; SSE42-NEXT:    mfence
+; SSE42-NEXT:    lock orl $0, (%esp)
 ; SSE42-NEXT:    retl
 ;
 ; NOSSE-LABEL: test1:
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -26423,9 +26423,10 @@
                                               Ops, MVT::i64,
                                               Node->getMemOperand());
 
-      // If this is a sequentially consistent store, also emit an mfence.
+      // If this is a sequentially consistent store, also emit an appropriate
+      // barrier 
       if (IsSeqCst)
-        Chain = DAG.getNode(X86ISD::MFENCE, dl, MVT::Other, Chain);
+        Chain = emitLockedStackOp(DAG, Subtarget, Chain, dl);
 
       return Chain;
     }


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