[PATCH] D57491: [DAGCombine] Avoid CombineZExtLogicopShiftLoad if there is free ZEXT

[Guozhi Wei via Phabricator via llvm-commits]

Carrot updated this revision to Diff 184519.
Carrot marked an inline comment as done.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57491/new/

https://reviews.llvm.org/D57491

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/pr39098.ll


Index: test/CodeGen/X86/pr39098.ll
===================================================================
--- test/CodeGen/X86/pr39098.ll
+++ test/CodeGen/X86/pr39098.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+define dso_local void @test_cancel2(i40* %p1, i40* %p2) {
+; CHECK:       # %entry
+; CHECK-NEXT:  movl    (%rdi), %eax
+; CHECK-NEXT:  shrl    %eax
+; CHECK-NEXT:  andl    $524287, %eax
+; CHECK-NEXT:  movl    %eax, (%rsi)
+; CHECK-NEXT:  movb    $0, 4(%rsi)
+; CHECK-NEXT:  retq
+entry:
+  %0 = load i40, i40* %p1, align 8
+  %shl414 = shl i40 %0, 19
+  %unsclear415 = and i40 %shl414, 549755813887
+  %shr416 = lshr i40 %unsclear415, 20
+  %unsclear417 = and i40 %shr416, 549755813887
+  store i40 %unsclear417, i40* %p2, align 8
+  ret void
+}
+
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8390,6 +8390,9 @@
 SDValue DAGCombiner::CombineZExtLogicopShiftLoad(SDNode *N) {
   assert(N->getOpcode() == ISD::ZERO_EXTEND);
   EVT VT = N->getValueType(0);
+  EVT OrigVT = N->getOperand(0).getValueType();
+  if (TLI.isZExtFree(OrigVT, VT))
+    return SDValue();
 
   // and/or/xor
   SDValue N0 = N->getOperand(0);


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