New approach to r136737: insert the necessary fences for atomic ops in platform-independent code, since a bunch of platforms (ARM, Mips, PPC, Alpha are the relevant targets here) need to do essentially the same thing.

I think this completes the basic CodeGen for atomicrmw and cmpxchg.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136813 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index 3484a79c73..8daec8ee48 100644
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -714,6 +714,13 @@ public:
     return ShouldFoldAtomicFences;
   }
 
+  /// getInsertFencesFor - return whether the DAG builder should automatically
+  /// insert fences and reduce ordering for atomics.
+  ///
+  bool getInsertFencesForAtomic() const {
+    return InsertFencesForAtomic;
+  }
+
   /// getPreIndexedAddressParts - returns true by value, base pointer and
   /// offset pointer and addressing mode by reference if the node's address
   /// can be legally represented as pre-indexed load / store address.
@@ -1134,6 +1141,13 @@ protected:
     ShouldFoldAtomicFences = fold;
   }
 
+  /// setInsertFencesForAtomic - Set if the the DAG builder should
+  /// automatically insert fences and reduce the order of atomic memory
+  /// operations to Monotonic.
+  void setInsertFencesForAtomic(bool fence) {
+    InsertFencesForAtomic = fence;
+  }
+
 public:
   //===--------------------------------------------------------------------===//
   // Lowering methods - These methods must be implemented by targets so that
@@ -1673,6 +1687,11 @@ private:
   /// combiner.
   bool ShouldFoldAtomicFences;
 
+  /// InsertFencesForAtomic - Whether the DAG builder should automatically
+  /// insert fences and reduce ordering for atomics.  (This will be set for
+  /// for most architectures with weak memory ordering.)
+  bool InsertFencesForAtomic;
+
   /// StackPointerRegisterToSaveRestore - If set to a physical register, this
   /// specifies the register that llvm.savestack/llvm.restorestack should save
   /// and restore.