[X86][AMDGPU][DAGCombiner] Move call to allowsMemoryAccess into isLoadBitCastBeneficial/isStoreBitCastBeneficial to allow X86 to bypass it

Basically the problem is that X86 doesn't set the Fast flag from
allowsMemoryAccess on certain CPUs due to slow unaligned memory
subtarget features. This prevents bitcasts from being folded into
loads and stores. But all vector loads and stores of the same width
are the same cost on X86.

This patch merges the allowsMemoryAccess call into isLoadBitCastBeneficial to allow X86 to skip it.

Differential Revision: https://reviews.llvm.org/D64295

llvm-svn: 365549

1 files changed, 8 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cd5de4c1400..09e1195e1fd 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11040,14 +11040,11 @@ SDValue DAGCombiner::visitBITCAST(SDNode *N) {
       // as we assume software couldn't rely on the number of accesses of an
       // illegal type.
       ((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
-       TLI.isOperationLegal(ISD::LOAD, VT)) &&
-      TLI.isLoadBitCastBeneficial(N0.getValueType(), VT)) {
+       TLI.isOperationLegal(ISD::LOAD, VT))) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0);
 
-    bool Fast = false;
-    if (TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VT,
-                               *LN0->getMemOperand(), &Fast) &&
-        Fast) {
+    if (TLI.isLoadBitCastBeneficial(N0.getValueType(), VT, DAG,
+                                    *LN0->getMemOperand())) {
       SDValue Load =
           DAG.getLoad(VT, SDLoc(N), LN0->getChain(), LN0->getBasePtr(),
                       LN0->getPointerInfo(), LN0->getAlignment(),
@@ -16174,15 +16171,11 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
     // illegal type.
     if (((!LegalOperations && !ST->isVolatile()) ||
          TLI.isOperationLegal(ISD::STORE, SVT)) &&
-        TLI.isStoreBitCastBeneficial(Value.getValueType(), SVT)) {
-      bool Fast = false;
-      if (TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), SVT,
-                                 *ST->getMemOperand(), &Fast) &&
-          Fast) {
-        return DAG.getStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
-                            ST->getPointerInfo(), ST->getAlignment(),
-                            ST->getMemOperand()->getFlags(), ST->getAAInfo());
-      }
+        TLI.isStoreBitCastBeneficial(Value.getValueType(), SVT,
+                                     DAG, *ST->getMemOperand())) {
+      return DAG.getStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
+                          ST->getPointerInfo(), ST->getAlignment(),
+                          ST->getMemOperand()->getFlags(), ST->getAAInfo());
     }
   }