From c0f190a0484b56e6d546e13b101b3662b253d6ea Mon Sep 17 00:00:00 2001
From: Amaury Sechet <deadalnix@gmail.com>
Date: Wed, 21 Aug 2019 18:51:08 +0000
Subject: [PATCH] [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

llvm-svn: 369561
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 3 +--
 llvm/test/CodeGen/X86/fixup-bw-copy.ll        | 2 +-
 llvm/test/CodeGen/X86/load-combine.ll         | 4 ++--
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 2672f20..3033635 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1148,7 +1148,6 @@ SDValue DAGCombiner::reassociateOpsCommutative(unsigned Opc, const SDLoc &DL,
       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(SDValue Op) {
     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.
diff --git a/llvm/test/CodeGen/X86/fixup-bw-copy.ll b/llvm/test/CodeGen/X86/fixup-bw-copy.ll
index ed15ec3..16a70e0 100644
--- a/llvm/test/CodeGen/X86/fixup-bw-copy.ll
+++ b/llvm/test/CodeGen/X86/fixup-bw-copy.ll
@@ -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
diff --git a/llvm/test/CodeGen/X86/load-combine.ll b/llvm/test/CodeGen/X86/load-combine.ll
index 99e444e..1d08ee0 100644
--- a/llvm/test/CodeGen/X86/load-combine.ll
+++ b/llvm/test/CodeGen/X86/load-combine.ll
@@ -1016,7 +1016,7 @@ define i32 @load_i32_by_i8_zaext_loads(i8* %arg, i32 %arg1) {
 ; 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(i8* %arg, i32 %arg1) {
 ; 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:
-- 
2.7.4