LowerAtomic: Don't skip optnone functions; atomic still need lowering (PR34020)

zmodem · zmodem · commit 66f6fc0a4923 · 2017-08-23T15:43:28.000Z
The lowering isn't really an optimization, so optnone shouldn't make a difference. ARM relies on the pass running when using "-mthread-model single", because in that mode, it doesn't run AtomicExpand. See bug for more details. Differential Revision: https://reviews.llvm.org/D37040 llvm-svn: 311565
diff --git a/llvm/lib/Transforms/Scalar/LowerAtomic.cpp b/llvm/lib/Transforms/Scalar/LowerAtomic.cpp
@@ -155,8 +155,7 @@ class LowerAtomicLegacyPass : public FunctionPass {
   }
 
   bool runOnFunction(Function &F) override {
-    if (skipFunction(F))
-      return false;
+    // Don't skip optnone functions; atomics still need to be lowered.
     FunctionAnalysisManager DummyFAM;
     auto PA = Impl.run(F, DummyFAM);
     return !PA.areAllPreserved();
diff --git a/llvm/test/Feature/optnone-opt.ll b/llvm/test/Feature/optnone-opt.ll
@@ -57,7 +57,6 @@ attributes #0 = { optnone noinline }
 ; Additional IR passes that opt doesn't turn on by default.
 ; OPT-MORE-DAG: Skipping pass 'Dead Code Elimination'
 ; OPT-MORE-DAG: Skipping pass 'Dead Instruction Elimination'
-; OPT-MORE-DAG: Skipping pass 'Lower atomic intrinsics
 
 ; Loop IR passes that opt doesn't turn on by default.
 ; OPT-LOOP-DAG: Skipping pass 'Delete dead loops'
diff --git a/llvm/test/Transforms/LowerAtomic/atomic-swap.ll b/llvm/test/Transforms/LowerAtomic/atomic-swap.ll
@@ -26,3 +26,14 @@ define i8 @swap() {
   ret i8 %j
 ; CHECK: ret i8 [[INST]]
 }
+
+
+define i8 @swap_optnone() noinline optnone {
+; CHECK-LABEL: @swap_optnone(
+  %i = alloca i8
+  %j = atomicrmw xchg i8* %i, i8 42 monotonic
+; CHECK: [[INST:%[a-z0-9]+]] = load
+; CHECK-NEXT: store
+  ret i8 %j
+; CHECK: ret i8 [[INST]]
+}

Original file line number	Diff line number	Diff line change
`@@ -155,8 +155,7 @@ class LowerAtomicLegacyPass : public FunctionPass {`
`155`	`155`	`}`
`156`	`156`
`157`	`157`	`bool runOnFunction(Function &F) override {`
`158`		`- if (skipFunction(F))`
`159`		`- return false;`
	`158`	`+ // Don't skip optnone functions; atomics still need to be lowered.`
`160`	`159`	`FunctionAnalysisManager DummyFAM;`
`161`	`160`	`auto PA = Impl.run(F, DummyFAM);`
`162`	`161`	`return !PA.areAllPreserved();`