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Fixes two issue in SimplifyDemandedBits of sext_in_reg: 

1) We should not try to simplify if the sext has multiple uses
2) There is no need to simplify is the source value is already sign-extended.

Patch by Gil Rapaport <gil.rapaport@intel.com>

Differential Revision: http://reviews.llvm.org/D6949

llvm-svn: 229659
This commit is contained in:
Michael Kuperstein 2015-02-18 09:43:40 +00:00
parent b7e5909a42
commit af9befa6b7
3 changed files with 27 additions and 24 deletions
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27
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
View File

@ -793,19 +793,26 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
APInt MsbMask = APInt::getHighBitsSet(BitWidth, 1); APInt MsbMask = APInt::getHighBitsSet(BitWidth, 1);
// If we only care about the highest bit, don't bother shifting right. // If we only care about the highest bit, don't bother shifting right.
if (MsbMask == DemandedMask) { if (MsbMask == NewMask) {
unsigned ShAmt = ExVT.getScalarType().getSizeInBits(); unsigned ShAmt = ExVT.getScalarType().getSizeInBits();
SDValue InOp = Op.getOperand(0); SDValue InOp = Op.getOperand(0);
unsigned VTBits = Op->getValueType(0).getScalarType().getSizeInBits();
bool AlreadySignExtended =
TLO.DAG.ComputeNumSignBits(InOp) >= VTBits-ShAmt+1;
// However if the input is already sign extended we expect the sign
// extension to be dropped altogether later and do not simplify.
if (!AlreadySignExtended) {
// Compute the correct shift amount type, which must be getShiftAmountTy
// for scalar types after legalization.
EVT ShiftAmtTy = Op.getValueType();
if (TLO.LegalTypes() && !ShiftAmtTy.isVector())
ShiftAmtTy = getShiftAmountTy(ShiftAmtTy);
// Compute the correct shift amount type, which must be getShiftAmountTy SDValue ShiftAmt = TLO.DAG.getConstant(BitWidth - ShAmt, ShiftAmtTy);
// for scalar types after legalization. return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl,
EVT ShiftAmtTy = Op.getValueType(); Op.getValueType(), InOp,
if (TLO.LegalTypes() && !ShiftAmtTy.isVector()) ShiftAmt));
ShiftAmtTy = getShiftAmountTy(ShiftAmtTy); }
SDValue ShiftAmt = TLO.DAG.getConstant(BitWidth - ShAmt, ShiftAmtTy);
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl,
Op.getValueType(), InOp, ShiftAmt));
} }
// Sign extension. Compute the demanded bits in the result that are not // Sign extension. Compute the demanded bits in the result that are not

4
llvm/test/CodeGen/X86/vector-blend.ll
View File

@ -419,8 +419,8 @@ define <8 x i64> @vsel_i648(<8 x i64> %v1, <8 x i64> %v2) {
; ;
; SSE41-LABEL: vsel_i648: ; SSE41-LABEL: vsel_i648:
; SSE41: # BB#0: # %entry ; SSE41: # BB#0: # %entry
; SSE41-NEXT: pblendw {{.*#+}} xmm0 = xmm0[0,1,2,3],xmm4[4,5,6,7] ; SSE41-NEXT: blendpd {{.*#+}} xmm0 = xmm0[0],xmm4[1]
; SSE41-NEXT: pblendw {{.*#+}} xmm2 = xmm2[0,1,2,3],xmm6[4,5,6,7] ; SSE41-NEXT: blendpd {{.*#+}} xmm2 = xmm2[0],xmm6[1]
; SSE41-NEXT: movaps %xmm5, %xmm1 ; SSE41-NEXT: movaps %xmm5, %xmm1
; SSE41-NEXT: movaps %xmm7, %xmm3 ; SSE41-NEXT: movaps %xmm7, %xmm3
; SSE41-NEXT: retq ; SSE41-NEXT: retq

20
llvm/test/CodeGen/X86/vselect-avx.ll
View File

@ -59,19 +59,15 @@ bb:
; ;
; <rdar://problem/18819506> ; <rdar://problem/18819506>
; Note: For now, hard code ORIG_MASK and SHRUNK_MASK registers, because we
; cannot express that ORIG_MASK must not be equal to ORIG_MASK. Otherwise,
; even a faulty pattern would pass!
;
; CHECK-LABEL: test3: ; CHECK-LABEL: test3:
; Compute the original mask. ; Compute the mask.
; CHECK: vpcmpeqd {{%xmm[0-9]+}}, {{%xmm[0-9]+}}, [[ORIG_MASK:%xmm0]] ; CHECK: vpcmpeqd {{%xmm[0-9]+}}, {{%xmm[0-9]+}}, [[MASK:%xmm[0-9]+]]
; Shrink the bit of the mask. ; Do not shrink the bit of the mask.
; CHECK-NEXT: vpslld $31, [[ORIG_MASK]], [[SHRUNK_MASK:%xmm3]] ; CHECK-NOT: vpslld $31, [[MASK]], {{%xmm[0-9]+}}
; Use the shrunk mask in the blend. ; Use the mask in the blend.
; CHECK-NEXT: vblendvps [[SHRUNK_MASK]], %xmm{{[0-9]+}}, %xmm{{[0-9]+}}, %xmm{{[0-9]+}} ; CHECK-NEXT: vblendvps [[MASK]], %xmm{{[0-9]+}}, %xmm{{[0-9]+}}, %xmm{{[0-9]+}}
; Use the original mask in the and. ; Use the mask in the and.
; CHECK-NEXT: vpand LCPI2_2(%rip), [[ORIG_MASK]], {{%xmm[0-9]+}} ; CHECK-NEXT: vpand LCPI2_2(%rip), [[MASK]], {{%xmm[0-9]+}}
; CHECK: retq ; CHECK: retq
define void @test3(<4 x i32> %induction30, <4 x i16>* %tmp16, <4 x i16>* %tmp17, <4 x i16> %tmp3, <4 x i16> %tmp12) { define void @test3(<4 x i32> %induction30, <4 x i16>* %tmp16, <4 x i16>* %tmp17, <4 x i16> %tmp3, <4 x i16> %tmp12) {
%tmp6 = srem <4 x i32> %induction30, <i32 3, i32 3, i32 3, i32 3> %tmp6 = srem <4 x i32> %induction30, <i32 3, i32 3, i32 3, i32 3>