Make sure no loads resulting from load->switch DAGCombine are marked invariant

Currently when DAGCombine converts loads feeding a switch into a switch of
addresses feeding a load the new load inherits the isInvariant flag of the left
side. This is incorrect since invariant loads can be reordered in cases where it
is illegal to reoarder normal loads.

This patch adds an isInvariant parameter to getExtLoad() and updates all call
sites to pass in the data if they have it or false if they don't. It also
changes the DAGCombine to use that data to make the right decision when
creating the new load.

llvm-svn: 214449

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/Target/XCore/XCoreISelLowering.cpp b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
index 780e971daf2..f3e14dc2746 100644
--- a/llvm/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
@@ -463,14 +463,15 @@ LowerLOAD(SDValue Op, SelectionDAG &DAG) const {
   if (LD->getAlignment() == 2) {
     SDValue Low = DAG.getExtLoad(ISD::ZEXTLOAD, DL, MVT::i32, Chain,
                                  BasePtr, LD->getPointerInfo(), MVT::i16,
-                                 LD->isVolatile(), LD->isNonTemporal(), 2);
+                                 LD->isVolatile(), LD->isNonTemporal(),
+                                 LD->isInvariant(), 2);
     SDValue HighAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, BasePtr,
                                    DAG.getConstant(2, MVT::i32));
     SDValue High = DAG.getExtLoad(ISD::EXTLOAD, DL, MVT::i32, Chain,
                                   HighAddr,
                                   LD->getPointerInfo().getWithOffset(2),
                                   MVT::i16, LD->isVolatile(),
-                                  LD->isNonTemporal(), 2);
+                                  LD->isNonTemporal(), LD->isInvariant(), 2);
     SDValue HighShifted = DAG.getNode(ISD::SHL, DL, MVT::i32, High,
                                       DAG.getConstant(16, MVT::i32));
     SDValue Result = DAG.getNode(ISD::OR, DL, MVT::i32, Low, HighShifted);
@@ -981,13 +982,13 @@ LowerATOMIC_LOAD(SDValue Op, SelectionDAG &DAG) const {
     return DAG.getExtLoad(ISD::EXTLOAD, SDLoc(Op), MVT::i32, N->getChain(),
                           N->getBasePtr(), N->getPointerInfo(), MVT::i16,
                           N->isVolatile(), N->isNonTemporal(),
-                          N->getAlignment(), N->getAAInfo());
+                          N->isInvariant(), N->getAlignment(), N->getAAInfo());
   }
   if (N->getMemoryVT() == MVT::i8)
     return DAG.getExtLoad(ISD::EXTLOAD, SDLoc(Op), MVT::i32, N->getChain(),
                           N->getBasePtr(), N->getPointerInfo(), MVT::i8,
                           N->isVolatile(), N->isNonTemporal(),
-                          N->getAlignment(), N->getAAInfo());
+                          N->isInvariant(), N->getAlignment(), N->getAAInfo());
   return SDValue();
 }