[llvm] r369561 - [DAGCombiner] Remove mostly redundant calls to AddToWorklist

[Amaury Sechet via llvm-commits]

Author: deadalnix
Date: Wed Aug 21 11:51:08 2019
New Revision: 369561

URL: http://llvm.org/viewvc/llvm-project?rev=369561&view=rev
Log:
[DAGCombiner] Remove mostly redundant calls to AddToWorklist

Summary:
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.

Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66543

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

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=369561&r1=369560&r2=369561&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Aug 21 11:51:08 2019
@@ -1148,7 +1148,6 @@ SDValue DAGCombiner::reassociateOpsCommu
       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 DAGCombiner::PromoteIntShiftOp(S
     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 @@ SDValue DAGCombiner::visitAND(SDNode *N)
       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.

Modified: llvm/trunk/test/CodeGen/X86/fixup-bw-copy.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/fixup-bw-copy.ll?rev=369561&r1=369560&r2=369561&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/fixup-bw-copy.ll (original)
+++ llvm/trunk/test/CodeGen/X86/fixup-bw-copy.ll Wed Aug 21 11:51:08 2019
@@ -52,7 +52,7 @@ define i8 @test_movb_hreg(i16 %a0) {
 ;
 ; 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

Modified: llvm/trunk/test/CodeGen/X86/load-combine.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/load-combine.ll?rev=369561&r1=369560&r2=369561&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/load-combine.ll (original)
+++ llvm/trunk/test/CodeGen/X86/load-combine.ll Wed Aug 21 11:51:08 2019
@@ -1016,7 +1016,7 @@ define i32 @load_i32_by_i8_zaext_loads(i
 ; 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 @@ define i32 @load_i32_by_i8_zsext_loads(i
 ; 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: