Bug 19348: Check for legal ExtLoad operation before folding

(aext (zextload x)) -> (aext (truncate (*extload x)))

Patch by Stanislav Mekhanoshin!

llvm-svn: 205805

1 files changed, 12 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cc0c5fa0766..fc31e26986b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5507,16 +5507,19 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
       !ISD::isNON_EXTLoad(N0.getNode()) && ISD::isUNINDEXEDLoad(N0.getNode()) &&
       N0.hasOneUse()) {
     LoadSDNode *LN0 = cast<LoadSDNode>(N0);
+    ISD::LoadExtType ExtType = LN0->getExtensionType();
     EVT MemVT = LN0->getMemoryVT();
-    SDValue ExtLoad = DAG.getExtLoad(LN0->getExtensionType(), SDLoc(N),
-                                     VT, LN0->getChain(), LN0->getBasePtr(),
-                                     MemVT, LN0->getMemOperand());
-    CombineTo(N, ExtLoad);
-    CombineTo(N0.getNode(),
-              DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
-                          N0.getValueType(), ExtLoad),
-              ExtLoad.getValue(1));
-    return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+    if (!LegalOperations || TLI.isLoadExtLegal(ExtType, MemVT)) {
+      SDValue ExtLoad = DAG.getExtLoad(ExtType, SDLoc(N),
+                                       VT, LN0->getChain(), LN0->getBasePtr(),
+                                       MemVT, LN0->getMemOperand());
+      CombineTo(N, ExtLoad);
+      CombineTo(N0.getNode(),
+                DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
+                            N0.getValueType(), ExtLoad),
+                ExtLoad.getValue(1));
+      return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+    }
   }
 
   if (N0.getOpcode() == ISD::SETCC) {