[SROA] Don't de-atomic volatile loads and stores

Volatile loads and stores are made visible in global state regardless of
what memory is involved.  It is not correct to disregard the ordering
and synchronization scope because it is possible to synchronize with
memory operations performed by hardware.

This partially addresses PR23737.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242126 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index 056dd11b5ab329e6a03e6e5f4b7f11e0ac7877b1..d1a0a82b9b08e7366512e5b953cedd4e9a47d8b7 100644 (file)
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -2593,13 +2593,21 @@ private:
       V = rewriteIntegerLoad(LI);
     } else if (NewBeginOffset == NewAllocaBeginOffset &&
                canConvertValue(DL, NewAllocaTy, LI.getType())) {
-      V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), LI.isVolatile(),
-                                LI.getName());
+      LoadInst *NewLI = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(),
+                                              LI.isVolatile(), LI.getName());
+      if (LI.isVolatile())
+        NewLI->setAtomic(LI.getOrdering(), LI.getSynchScope());
+
+      V = NewLI;
     } else {
       Type *LTy = TargetTy->getPointerTo();
-      V = IRB.CreateAlignedLoad(getNewAllocaSlicePtr(IRB, LTy),
-                                getSliceAlign(TargetTy), LI.isVolatile(),
-                                LI.getName());
+      LoadInst *NewLI = IRB.CreateAlignedLoad(getNewAllocaSlicePtr(IRB, LTy),
+                                              getSliceAlign(TargetTy),
+                                              LI.isVolatile(), LI.getName());
+      if (LI.isVolatile())
+        NewLI->setAtomic(LI.getOrdering(), LI.getSynchScope());
+
+      V = NewLI;
       IsPtrAdjusted = true;
     }
     V = convertValue(DL, IRB, V, TargetTy);
@@ -2722,7 +2730,8 @@ private:
       NewSI = IRB.CreateAlignedStore(V, NewPtr, getSliceAlign(V->getType()),
                                      SI.isVolatile());
     }
-    (void)NewSI;
+    if (SI.isVolatile())
+      NewSI->setAtomic(SI.getOrdering(), SI.getSynchScope());
     Pass.DeadInsts.insert(&SI);
     deleteIfTriviallyDead(OldOp);
 

diff --git a/test/Transforms/SROA/basictest.ll b/test/Transforms/SROA/basictest.ll
index a59192d718cf461a97ea959c33aebfda7b239498..7c8955b28fa2d871a22264e232774f5f03d42ac2 100644 (file)
--- a/test/Transforms/SROA/basictest.ll
+++ b/test/Transforms/SROA/basictest.ll
@@ -1595,3 +1595,14 @@ entry:
   store i32 %load, i32* %a.gep1
   ret void
 }
+
+define void @PR23737() {
+; CHECK-LABEL: @PR23737(
+; CHECK: store atomic volatile {{.*}} seq_cst
+; CHECK: load atomic volatile {{.*}} seq_cst
+entry:
+  %ptr = alloca i64, align 8
+  store atomic volatile i64 0, i64* %ptr seq_cst, align 8
+  %load = load atomic volatile i64, i64* %ptr seq_cst, align 8
+  ret void
+}