Commit f04284cf authored by Simon Pilgrim's avatar Simon Pilgrim
Browse files

[TargetLowering] SimplifyDemandedBits ISD::SRA multi-use handling 

Call SimplifyMultipleUseDemandedBits to peek through extended source args with multiple uses
parent 81f385b0

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

+10 −0
Original line number Diff line number Diff line
@@ -1534,6 +1534,16 @@ bool TargetLowering::SimplifyDemandedBits( 
      if (Known.One[BitWidth - ShAmt - 1])

        // New bits are known one.

        Known.One.setHighBits(ShAmt);



      // Attempt to avoid multi-use ops if we don't need anything from them.

      if (!InDemandedMask.isAllOnesValue() || !DemandedElts.isAllOnesValue()) {

        SDValue DemandedOp0 = SimplifyMultipleUseDemandedBits(

            Op0, InDemandedMask, DemandedElts, TLO.DAG, Depth + 1);

        if (DemandedOp0) {

          SDValue NewOp = TLO.DAG.getNode(ISD::SRA, dl, VT, DemandedOp0, Op1);

          return TLO.CombineTo(Op, NewOp);

        }

      }

    }

    break;

  }

llvm/test/CodeGen/X86/const-shift-of-constmasked.ll

+2 −2
Original line number Diff line number Diff line
@@ -1870,9 +1870,9 @@ define i64 @test_i64_18446744065119617024_mask_ashr_1(i64 %a0) { 
define i64 @test_i64_18446744065119617024_mask_ashr_32(i64 %a0) {

; X32-LABEL: test_i64_18446744065119617024_mask_ashr_32:

; X32:       # %bb.0:

; X32-NEXT:    movl {{[0-9]+}}(%esp), %eax

; X32-NEXT:    movl {{[0-9]+}}(%esp), %edx

; X32-NEXT:    movl %edx, %eax

; X32-NEXT:    andl $-2, %eax

; X32-NEXT:    movl %eax, %edx

; X32-NEXT:    sarl $31, %edx

; X32-NEXT:    retl

;