[PATCH] D42783: [DAGCombiner] When folding fold (sext/zext (and/or/xor (sextload/zextload x), cst)) -> (and/or/xor (sextload/zextload x), (sext/zext cst)) make sure we check the legality of the full extended load.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, spatel.

If the load is already an extended load we should be using the memory VT for the legality check, not just the VT of the current extension.

I don't have a test case, just noticed it while investigating some load extension improvements.


Repository:
  rL LLVM

https://reviews.llvm.org/D42783

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp


Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7590,10 +7590,11 @@
        N0.getOpcode() == ISD::XOR) &&
       isa<LoadSDNode>(N0.getOperand(0)) &&
       N0.getOperand(1).getOpcode() == ISD::Constant &&
-      TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, N0.getValueType()) &&
       (!LegalOperations && TLI.isOperationLegal(N0.getOpcode(), VT))) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0.getOperand(0));
-    if (LN0->getExtensionType() != ISD::ZEXTLOAD && LN0->isUnindexed()) {
+    EVT MemVT = LN0->getMemoryVT();
+    if (TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, MemVT) &&
+      LN0->getExtensionType() != ISD::ZEXTLOAD && LN0->isUnindexed()) {
       bool DoXform = true;
       SmallVector<SDNode*, 4> SetCCs;
       if (!N0.hasOneUse())
@@ -7882,10 +7883,11 @@
        N0.getOpcode() == ISD::XOR) &&
       isa<LoadSDNode>(N0.getOperand(0)) &&
       N0.getOperand(1).getOpcode() == ISD::Constant &&
-      TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, N0.getValueType()) &&
       (!LegalOperations && TLI.isOperationLegal(N0.getOpcode(), VT))) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0.getOperand(0));
-    if (LN0->getExtensionType() != ISD::SEXTLOAD && LN0->isUnindexed()) {
+    EVT MemVT = LN0->getMemoryVT();
+    if (TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, MemVT) &&
+        LN0->getExtensionType() != ISD::SEXTLOAD && LN0->isUnindexed()) {
       bool DoXform = true;
       SmallVector<SDNode*, 4> SetCCs;
       if (!N0.hasOneUse()) {


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D42783.132330.patch
Type: text/x-patch
Size: 1608 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180201/a9ba133a/attachment.bin>