[PATCH] D66543: [DAGCombiner] Remove mostly redundant calls to AddToWorklist

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix created this revision.
deadalnix added reviewers: craig.topper, efriedma, RKSimon, lebedev.ri.
Herald added a project: LLVM.
deadalnix retitled this revision from "[DAGCombiner] Remove ostl redundant calls to AddToWorklist" to "[DAGCombiner] Remove mostly redundant calls to AddToWorklist".

These calls change the order in which some nodes are processed and so have an effect on codegen.

The change in fixup-bw-copy.ll is due to (and (load anyext)) gets transformed into (load zext) while previously the and was removed by SimplifyDemandedBits, so the (load anyext) remained.


Repository:
  rL LLVM

https://reviews.llvm.org/D66543

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/fixup-bw-copy.ll
  test/CodeGen/X86/load-combine.ll


Index: test/CodeGen/X86/load-combine.ll
===================================================================
--- test/CodeGen/X86/load-combine.ll
+++ test/CodeGen/X86/load-combine.ll
@@ -1016,7 +1016,7 @@
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; CHECK-NEXT:    movl 12(%ecx,%eax), %eax
+; CHECK-NEXT:    movl 12(%eax,%ecx), %eax
 ; CHECK-NEXT:    retl
 ;
 ; CHECK64-LABEL: load_i32_by_i8_zaext_loads:
@@ -1072,7 +1072,7 @@
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; CHECK-NEXT:    movl 12(%ecx,%eax), %eax
+; CHECK-NEXT:    movl 12(%eax,%ecx), %eax
 ; CHECK-NEXT:    retl
 ;
 ; CHECK64-LABEL: load_i32_by_i8_zsext_loads:
Index: test/CodeGen/X86/fixup-bw-copy.ll
===================================================================
--- test/CodeGen/X86/fixup-bw-copy.ll
+++ test/CodeGen/X86/fixup-bw-copy.ll
@@ -52,7 +52,7 @@
 ;
 ; X32-LABEL: test_movb_hreg:
 ; X32:       # %bb.0:
-; X32-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X32-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
 ; X32-NEXT:    addb %al, %ah
 ; X32-NEXT:    movb %ah, %al
 ; X32-NEXT:    retl
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1148,7 +1148,6 @@
       SDValue OpNode = DAG.getNode(Opc, SDLoc(N0), VT, N0.getOperand(0), N1);
       if (!OpNode.getNode())
         return SDValue();
-      AddToWorklist(OpNode.getNode());
       return DAG.getNode(Opc, DL, VT, OpNode, N0.getOperand(1));
     }
   }
@@ -1462,7 +1461,6 @@
     SDValue RV =
         DAG.getNode(ISD::TRUNCATE, DL, VT, DAG.getNode(Opc, DL, PVT, N0, N1));
 
-    AddToWorklist(N0.getNode());
     if (Replace)
       ReplaceLoadWithPromotedLoad(Op.getOperand(0).getNode(), N0.getNode());
 
@@ -5213,6 +5211,7 @@
       return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }
+
   // similarly fold (and (X (load ([non_ext|any_ext|zero_ext] V))), c) ->
   // (X (load ([non_ext|zero_ext] V))) if 'and' only clears top bits which must
   // already be zero by virtue of the width of the base type of the load.


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