[llvm] r326613 - [SystemZ] Allow LRV/STRV with volatile memory accesses

[Ulrich Weigand via llvm-commits]

Author: uweigand
Date: Fri Mar  2 12:51:59 2018
New Revision: 326613

URL: http://llvm.org/viewvc/llvm-project?rev=326613&view=rev
Log:
[SystemZ] Allow LRV/STRV with volatile memory accesses

The byte-swapping loads and stores do not actually perform multiple
accesses to their memory operand, so they are OK to use with volatile
memory operands as well.  Remove overly cautious check.


Modified:
    llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp

Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=326613&r1=326612&r2=326613&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Fri Mar  2 12:51:59 2018
@@ -5249,9 +5249,7 @@ SDValue SystemZTargetLowering::combineST
     }
   }
   // Combine STORE (BSWAP) into STRVH/STRV/STRVG
-  // See comment in combineBSWAP about volatile accesses.
   if (!SN->isTruncatingStore() &&
-      !SN->isVolatile() &&
       Op1.getOpcode() == ISD::BSWAP &&
       Op1.getNode()->hasOneUse() &&
       (Op1.getValueType() == MVT::i16 ||
@@ -5352,13 +5350,10 @@ SDValue SystemZTargetLowering::combineBS
     SDNode *N, DAGCombinerInfo &DCI) const {
   SelectionDAG &DAG = DCI.DAG;
   // Combine BSWAP (LOAD) into LRVH/LRV/LRVG
-  // These loads are allowed to access memory multiple times, and so we must check
-  // that the loads are not volatile before performing the combine.
   if (ISD::isNON_EXTLoad(N->getOperand(0).getNode()) &&
       N->getOperand(0).hasOneUse() &&
       (N->getValueType(0) == MVT::i16 || N->getValueType(0) == MVT::i32 ||
-       N->getValueType(0) == MVT::i64) &&
-       !cast<LoadSDNode>(N->getOperand(0))->isVolatile()) {
+       N->getValueType(0) == MVT::i64)) {
       SDValue Load = N->getOperand(0);
       LoadSDNode *LD = cast<LoadSDNode>(Load);