[PATCH] D54285: [DAGCombiner] Enable tryToFoldExtendOfConstant to run between legalize vector ops and legalize DAG

[Craig Topper via Phabricator via llvm-commits]

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

I believe it should be ok to create a new build_vector before legalize DAG since we don't legalize any build_vectors until legalize DAG.

I've added a new flag to DAGCombiner to reflect this level in a bool so we can pass it so the function without doing a compare to Level variable at each call site.

Unfortunately, X86's custom constant folding in combineVSZext is hiding any test changes from this. But I'm trying to get to a point where that X86 specific code isn't necessary at all.


https://reviews.llvm.org/D54285

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp


Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -119,6 +119,7 @@
     const TargetLowering &TLI;
     CombineLevel Level;
     CodeGenOpt::Level OptLevel;
+    bool LegalDAG = false;
     bool LegalOperations = false;
     bool LegalTypes = false;
     bool ForCodeSize;
@@ -1404,6 +1405,7 @@
 void DAGCombiner::Run(CombineLevel AtLevel) {
   // set the instance variables, so that the various visit routines may use it.
   Level = AtLevel;
+  LegalDAG = Level >= AfterLegalizeDAG;
   LegalOperations = Level >= AfterLegalizeVectorOps;
   LegalTypes = Level >= AfterLegalizeTypes;
 
@@ -8024,7 +8026,7 @@
 /// avoid introducing illegal build_vector dag nodes.
 static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
                                          SelectionDAG &DAG, bool LegalTypes,
-                                         bool LegalOperations) {
+                                         bool LegalDAG) {
   unsigned Opcode = N->getOpcode();
   SDValue N0 = N->getOperand(0);
   EVT VT = N->getValueType(0);
@@ -8045,7 +8047,7 @@
   // fold (aext (build_vector AllConstants) -> (build_vector AllConstants)
   EVT SVT = VT.getScalarType();
   if (!(VT.isVector() &&
-      (!LegalTypes || (!LegalOperations && TLI.isTypeLegal(SVT))) &&
+      (!LegalTypes || (!LegalDAG && TLI.isTypeLegal(SVT))) &&
       ISD::isBuildVectorOfConstantSDNodes(N0.getNode())))
     return nullptr;
 
@@ -8480,7 +8482,7 @@
   SDLoc DL(N);
 
   if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes,
-                                              LegalOperations))
+                                              LegalDAG))
     return SDValue(Res, 0);
 
   // fold (sext (sext x)) -> (sext x)
@@ -8719,7 +8721,7 @@
   EVT VT = N->getValueType(0);
 
   if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes,
-                                              LegalOperations))
+                                              LegalDAG))
     return SDValue(Res, 0);
 
   // fold (zext (zext x)) -> (zext x)
@@ -8969,7 +8971,7 @@
   EVT VT = N->getValueType(0);
 
   if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes,
-                                              LegalOperations))
+                                              LegalDAG))
     return SDValue(Res, 0);
 
   // fold (aext (aext x)) -> (aext x)
@@ -9496,7 +9498,7 @@
     return DAG.getUNDEF(VT);
 
   if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes,
-                                              LegalOperations))
+                                              LegalDAG))
     return SDValue(Res, 0);
 
   return SDValue();
@@ -9510,7 +9512,7 @@
     return DAG.getUNDEF(VT);
 
   if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes,
-                                              LegalOperations))
+                                              LegalDAG))
     return SDValue(Res, 0);
 
   return SDValue();


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