Remove unused ShouldFoldAtomicFences flag.

I think it's almost impossible to fold atomic fences profitably under
LLVM/C++11 semantics. As a result, this is now unused and just
cluttering up the target interface.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179940 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 0 insertions, 13 deletions

diff --git a/lib/Target/AArch64/AArch64ISelLowering.cpp b/lib/Target/AArch64/AArch64ISelLowering.cpp
index 6deae75..786b1ba 100644
--- a/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -59,10 +59,6 @@ AArch64TargetLowering::AArch64TargetLowering(AArch64TargetMachine &TM)
 
   computeRegisterProperties();
 
-  // We have particularly efficient implementations of atomic fences if they can
-  // be combined with nearby atomic loads and stores.
-  setShouldFoldAtomicFences(true);
-
   // We combine OR nodes for bitfield and NEON BSL operations.
   setTargetDAGCombine(ISD::OR);
 
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 698c8a7..23d7ef1 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -763,8 +763,6 @@ ARMTargetLowering::ARMTargetLowering(TargetMachine &TM)
     // Unordered/Monotonic case.
     setOperationAction(ISD::ATOMIC_LOAD, MVT::i32, Custom);
     setOperationAction(ISD::ATOMIC_STORE, MVT::i32, Custom);
-    // Since the libcalls include locking, fold in the fences
-    setShouldFoldAtomicFences(true);
   }
 
   setOperationAction(ISD::PREFETCH,         MVT::Other, Custom);
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 94370ae..b7ba0b8 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -528,13 +528,6 @@ void X86TargetLowering::resetOperationActions() {
 
   setOperationAction(ISD::ATOMIC_FENCE  , MVT::Other, Custom);
 
-  // On X86 and X86-64, atomic operations are lowered to locked instructions.
-  // Locked instructions, in turn, have implicit fence semantics (all memory
-  // operations are flushed before issuing the locked instruction, and they
-  // are not buffered), so we can fold away the common pattern of
-  // fence-atomic-fence.
-  setShouldFoldAtomicFences(true);
-
   // Expand certain atomics
   for (unsigned i = 0; i != array_lengthof(IntVTs); ++i) {
     MVT VT = IntVTs[i];