[PATCH] D61169: [CodeGenPrepare] Don't split the store if it is volatile

[Qing Shan Zhang via Phabricator via llvm-commits]

steven.zhang updated this revision to Diff 197054.
steven.zhang retitled this revision from "[CodeGenPrepare] When split the store, get the volatile flag from the old store" to "[CodeGenPrepare] Don't split the store if it is volatile".
steven.zhang edited the summary of this revision.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61169/new/

https://reviews.llvm.org/D61169

Files:
  llvm/lib/CodeGen/CodeGenPrepare.cpp
  llvm/test/CodeGen/PowerPC/splitstore-check-volatile.ll


Index: llvm/test/CodeGen/PowerPC/splitstore-check-volatile.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/splitstore-check-volatile.ll
@@ -0,0 +1,17 @@
+; Test that CodeGenPrepare respect the volatile flag when splitting a store.
+;
+; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -stop-after codegenprepare -force-split-store < %s  | FileCheck %s
+
+define void @fun(i16* %Src, i16* %Dst) {
+; CHECK: store volatile i16 %8, i16* %Dst 
+  %1 = load i16, i16* %Src
+  %2 = trunc i16 %1 to i8
+  %3 = lshr i16 %1, 8
+  %4 = trunc i16 %3 to i8
+  %5 = zext i8 %2 to i16
+  %6 = zext i8 %4 to i16
+  %7 = shl nuw i16 %6, 8
+  %8 = or i16 %7, %5
+  store volatile i16 %8, i16* %Dst
+  ret void
+}
Index: llvm/lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -6662,6 +6662,10 @@
       DL.getTypeSizeInBits(SplitStoreType))
     return false;
 
+  // Don't split the store if it is volatile.
+  if (SI.isVolatile())
+    return false;
+
   // Match the following patterns:
   // (store (or (zext LValue to i64),
   //            (shl (zext HValue to i64), 32)), HalfValBitSize)


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