Emit atomic memory order other than seq_cst on demand only

test/Transforms/NaCl/atomic/atomic_others.ll

-; RUN: opt -nacl-rewrite-atomics -S < %s | FileCheck %s
+; RUN: opt -nacl-rewrite-atomics -pnacl-memory-order-seq-cst-only=false -S < %s | FileCheck %s
 ;
 ; Validate that atomic non-{acquire/release/acq_rel/seq_cst} loads/stores get
 ; rewritten into NaCl atomic builtins with sequentially consistent memory
 ; ordering (enum value 6), and that acquire/release/acq_rel remain as-is (enum
 ; values 3/4/5).
 ;
 ; Note that monotonic doesn't exist in C11/C++11, and consume isn't implemented
 ; in LLVM yet.
 
 target datalayout = "p:32:32:32"
@@ skipping 21 matching lines @@
 
 ; CHECK-LABEL: @test_atomic_store_unordered_i32
 define void @test_atomic_store_unordered_i32(i32* %ptr, i32 %value) {
   ; CHECK-NEXT: call void @llvm.nacl.atomic.store.i32(i32 %value, i32* %ptr, i32 6)
   store atomic i32 %value, i32* %ptr unordered, align 4
   ret void  ; CHECK-NEXT: ret void
 }
 
 ; CHECK-LABEL: @test_atomic_load_acquire_i32
 define i32 @test_atomic_load_acquire_i32(i32* %ptr) {
   ; CHECK-NEXT: %res = call i32 @llvm.nacl.atomic.load.i32(i32* %ptr, i32 3)

[jvoung (off chromium), 2015/01/20 22:28:31]

Could you add a test run w/ the flag being default also, and check that 3/4/5 go
to 6?

[JF, 2015/01/21 03:50:03]

Done.

   %res = load atomic i32* %ptr acquire, align 4
   ret i32 %res  ; CHECK-NEXT: ret i32 %res
 }
 
 ; CHECK-LABEL: @test_atomic_store_release_i32
 define void @test_atomic_store_release_i32(i32* %ptr, i32 %value) {
   ; CHECK-NEXT: call void @llvm.nacl.atomic.store.i32(i32 %value, i32* %ptr, i32 4)
   store atomic i32 %value, i32* %ptr release, align 4
   ret void  ; CHECK-NEXT: ret void
 }
@@ skipping 67 matching lines @@
   ret { i32, i1 } %res
 }
 
 ; CHECK-LABEL: @test_cmpxchg_relaxed_relaxed
 define { i32, i1 } @test_cmpxchg_relaxed_relaxed(i32* %ptr, i32 %value) {
   ; Failure ordering is upgraded.
   ; CHECK-NEXT: %res = call i32 @llvm.nacl.atomic.cmpxchg.i32(i32* %ptr, i32 0, i32 %value, i32 6, i32 6)
   %res = cmpxchg i32* %ptr, i32 0, i32 %value monotonic monotonic
   ret { i32, i1 } %res
 }