[PATCH] D135844: [AArch64]Regard (shl val, N) as a potential bit-field-positioning op regardless of the number of uses; the rationale is that, 'val' could be used as bit extraction source as long as N (the left shift amount) fits BiggerPattern requirement

[Mingming Liu via Phabricator via llvm-commits]

mingmingl created this revision.
Herald added subscribers: hiraditya, kristof.beyls.
Herald added a project: All.
mingmingl requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D135844

Files:
  llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
  llvm/test/CodeGen/AArch64/bitfield-insert.ll


Index: llvm/test/CodeGen/AArch64/bitfield-insert.ll
===================================================================
--- llvm/test/CodeGen/AArch64/bitfield-insert.ll
+++ llvm/test/CodeGen/AArch64/bitfield-insert.ll
@@ -266,10 +266,9 @@
 ; CHECK-LABEL: test_nouseful_bits:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    and w8, w0, #0xff
+; CHECK-NEXT:    bfi w0, w8, #8, #8
 ; CHECK-NEXT:    lsl w8, w8, #8
-; CHECK-NEXT:    mov w9, w8
-; CHECK-NEXT:    bfxil w9, w0, #0, #8
-; CHECK-NEXT:    bfi w8, w9, #16, #16
+; CHECK-NEXT:    bfi w8, w0, #16, #16
 ; CHECK-NEXT:    mov w0, w8
 ; CHECK-NEXT:    ret
   %conv = zext i8 %a to i32     ;   0  0  0  A
Index: llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -2556,9 +2556,6 @@
   if (!isOpcWithIntImmediate(N, ISD::SHL, ShlImm))
     return false;
 
-  if (!BiggerPattern && !Op.hasOneUse())
-    return false;
-
   EVT VT = N->getValueType(0);
   assert((VT == MVT::i32 || VT == MVT::i64) &&
          "Caller guarantees that type is i32 or i64");


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D135844.467347.patch
Type: text/x-patch
Size: 1173 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20221013/007d0caa/attachment.bin>