[PATCH] D122915: [AArch64] UBFM fold in the MIPeepholeOpt.

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 updated this revision to Diff 420516.
bcl5980 added a comment.

Fix #54696 in tryBitfieldInsertOpFromOr


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D122915/new/

https://reviews.llvm.org/D122915

Files:
  llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
  llvm/test/CodeGen/AArch64/aarch64-lsr-bfi.ll


Index: llvm/test/CodeGen/AArch64/aarch64-lsr-bfi.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/aarch64-lsr-bfi.ll
@@ -0,0 +1,43 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=aarch64-none-linux-gnu < %s -o -| FileCheck %s
+
+define i32 @lsr_bfi(i32 %a) {
+; CHECK-LABEL: lsr_bfi:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    lsr w8, w0, #20
+; CHECK-NEXT:    bfi w0, w8, #4, #4
+; CHECK-NEXT:    ret
+  %and1 = and i32 %a, -241
+  %1 = lshr i32 %a, 16
+  %shl = and i32 %1, 240
+  %or = or i32 %shl, %and1
+  ret i32 %or
+}
+
+define i32 @negative_lsr_bfi0(i32 %a) {
+; CHECK-LABEL: negative_lsr_bfi0:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    and w0, w0, #0xffffff0f
+; CHECK-NEXT:    ret
+  %and1 = and i32 %a, -241
+  %1 = lshr i32 %a, 28
+  %shl = and i32 %1, 240
+  %or = or i32 %shl, %and1
+  ret i32 %or
+}
+
+define i32 @negative_lsr_bfi1(i32 %a) {
+; CHECK-LABEL: negative_lsr_bfi1:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    lsr w8, w0, #16
+; CHECK-NEXT:    lsr w9, w8, #4
+; CHECK-NEXT:    bfi w0, w9, #4, #4
+; CHECK-NEXT:    add w0, w0, w8
+; CHECK-NEXT:    ret
+  %and1 = and i32 %a, -241
+  %1 = lshr i32 %a, 16
+  %shl = and i32 %1, 240
+  %or = or i32 %shl, %and1
+  %add = add i32 %or, %1
+  ret i32 %add
+}
Index: llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -2714,8 +2714,16 @@
     // shift the needed bits into place.
     SDLoc DL(N);
     unsigned ShiftOpc = (VT == MVT::i32) ? AArch64::UBFMWri : AArch64::UBFMXri;
+    uint64_t LsrImm = LSB;
+    if (Src->hasOneUse() &&
+        isOpcWithIntImmediate(Src.getNode(), ISD::SRL, LsrImm) &&
+        (LsrImm + LSB) < BitWidth) {
+      Src = Src->getOperand(0);
+      LsrImm += LSB;
+    }
+
     SDNode *LSR = CurDAG->getMachineNode(
-        ShiftOpc, DL, VT, Src, CurDAG->getTargetConstant(LSB, DL, VT),
+        ShiftOpc, DL, VT, Src, CurDAG->getTargetConstant(LsrImm, DL, VT),
         CurDAG->getTargetConstant(BitWidth - 1, DL, VT));
 
     // BFXIL is an alias of BFM, so translate to BFM operands.


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