r238892 - [Sema] Make the atomic builtins more efficient by reducing volatility

[David Majnemer]

Author: majnemer
Date: Tue Jun  2 19:26:35 2015
New Revision: 238892

URL: http://llvm.org/viewvc/llvm-project?rev=238892&view=rev
Log:
[Sema] Make the atomic builtins more efficient by reducing volatility

The parameter types and return type do not need to be volatile just
because the pointer type's pointee type is volatile qualified.  This is
an unnecessary pessimization.

Modified:
    cfe/trunk/lib/Sema/SemaChecking.cpp
    cfe/trunk/test/CodeGen/atomic-ops.c

Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=238892&r1=238891&r2=238892&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Tue Jun  2 19:26:35 2015
@@ -1604,6 +1604,10 @@ ExprResult Sema::SemaAtomicOpsOverloaded
     return ExprError();
   }
 
+  // atomic_fetch_or takes a pointer to a volatile 'A'.  We shouldn't let the
+  // volatile-ness of the pointee-type inject itself into the result or the
+  // other operands.
+  ValType.removeLocalVolatile();
   QualType ResultType = ValType;
   if (Form == Copy || Form == GNUXchg || Form == Init)
     ResultType = Context.VoidTy;

Modified: cfe/trunk/test/CodeGen/atomic-ops.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/atomic-ops.c?rev=238892&r1=238891&r2=238892&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/atomic-ops.c (original)
+++ cfe/trunk/test/CodeGen/atomic-ops.c Tue Jun  2 19:26:35 2015
@@ -105,6 +105,14 @@ int fi3e(atomic_int *i) {
   return atomic_fetch_or(i, 1);
 }
 
+int fi3f(int *i) {
+  // CHECK-LABEL: @fi3f
+  // CHECK-NOT: store volatile
+  // CHECK: atomicrmw or
+  // CHECK-NOT: {{ or }}
+  return __atomic_fetch_or(i, (short)1, memory_order_seq_cst);
+}
+
 _Bool fi4(_Atomic(int) *i) {
   // CHECK-LABEL: @fi4(
   // CHECK: [[PAIR:%[.0-9A-Z_a-z]+]] = cmpxchg i32* [[PTR:%[.0-9A-Z_a-z]+]], i32 [[EXPECTED:%[.0-9A-Z_a-z]+]], i32 [[DESIRED:%[.0-9A-Z_a-z]+]]