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[x86] Teach the target shuffle mask extraction to recognize unary forms

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of normally binary shuffle instructions like PUNPCKL and MOVLHPS.

This detects cases where a single register is used for both operands
making the shuffle behave in a unary way. We detect this and adjust the
mask to use the unary form which allows the existing DAG combine for
shuffle instructions to actually work at all.

As a consequence, this uncovered a number of obvious bugs in the
existing DAG combine which are fixed. It also now canonicalizes several
shuffles even with the existing lowering. These typically are trying to
match the shuffle to the domain of the input where before we only really
modeled them with the floating point variants. All of the cases which
change to an integer shuffle here have something in the integer domain, so
there are no more or fewer domain crosses here AFAICT. Technically, it
might be better to go from a GPR directly to the floating point domain,
but detecting floating point *outputs* despite integer inputs is a lot
more code and seems unlikely to be worthwhile in practice. If folks are
seeing domain-crossing regressions here though, let me know and I can
hack something up to fix it.

Also as a consequence, a bunch of missed opportunities to form pshufb
now can be formed. Notably, splats of i8s now form pshufb.
Interestingly, this improves the existing splat lowering too. We go from
3 instructions to 1. Yes, we may tie up a register, but it seems very
likely to be worth it, especially if splatting the 0th byte (the
common case) as then we can use a zeroed register as the mask.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214625 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-08-02 10:27:38 +00:00
parent 8a64a46c97
commit fb1293fd4c
5 changed files with 50 additions and 61 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
lib/Target/X86/X86ISelLowering.cpp
View File

@ -5133,30 +5133,38 @@ static SDValue getShuffleVectorZeroOrUndef(SDValue V2, unsigned Idx,
}
/// getTargetShuffleMask - Calculates the shuffle mask corresponding to the
/// target specific opcode. Returns true if the Mask could be calculated.
/// Sets IsUnary to true if only uses one source.
/// target specific opcode. Returns true if the Mask could be calculated. Sets
/// IsUnary to true if only uses one source. Note that this will set IsUnary for
/// shuffles which use a single input multiple times, and in those cases it will
/// adjust the mask to only have indices within that single input.
static bool getTargetShuffleMask(SDNode *N, MVT VT,
SmallVectorImpl<int> &Mask, bool &IsUnary) {
unsigned NumElems = VT.getVectorNumElements();
SDValue ImmN;
IsUnary = false;
bool IsFakeUnary = false;
switch(N->getOpcode()) {
case X86ISD::SHUFP:
ImmN = N->getOperand(N->getNumOperands()-1);
DecodeSHUFPMask(VT, cast<ConstantSDNode>(ImmN)->getZExtValue(), Mask);
IsUnary = IsFakeUnary = N->getOperand(0) == N->getOperand(1);
break;
case X86ISD::UNPCKH:
DecodeUNPCKHMask(VT, Mask);
IsUnary = IsFakeUnary = N->getOperand(0) == N->getOperand(1);
break;
case X86ISD::UNPCKL:
DecodeUNPCKLMask(VT, Mask);
IsUnary = IsFakeUnary = N->getOperand(0) == N->getOperand(1);
break;
case X86ISD::MOVHLPS:
DecodeMOVHLPSMask(NumElems, Mask);
IsUnary = IsFakeUnary = N->getOperand(0) == N->getOperand(1);
break;
case X86ISD::MOVLHPS:
DecodeMOVLHPSMask(NumElems, Mask);
IsUnary = IsFakeUnary = N->getOperand(0) == N->getOperand(1);
break;
case X86ISD::PALIGNR:
ImmN = N->getOperand(N->getNumOperands()-1);
@ -5210,6 +5218,14 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
default: llvm_unreachable("unknown target shuffle node");
}
// If we have a fake unary shuffle, the shuffle mask is spread across two
// inputs that are actually the same node. Re-map the mask to always point
// into the first input.
if (IsFakeUnary)
for (int &M : Mask)
if (M >= (int)Mask.size())
M -= Mask.size();
return true;
}
@ -18735,6 +18751,8 @@ static bool combineX86ShuffleChain(SDValue Op, SDValue Root, ArrayRef<int> Mask,
bool Lo = Mask.equals(0, 0);
unsigned Shuffle = FloatDomain ? (Lo ? X86ISD::MOVLHPS : X86ISD::MOVHLPS)
: (Lo ? X86ISD::UNPCKL : X86ISD::UNPCKH);
if (Depth == 1 && Root->getOpcode() == Shuffle)
return false; // Nothing to do!
MVT ShuffleVT = FloatDomain ? MVT::v4f32 : MVT::v2i64;
Op = DAG.getNode(ISD::BITCAST, DL, ShuffleVT, Input);
DCI.AddToWorklist(Op.getNode());
@ -18757,16 +18775,18 @@ static bool combineX86ShuffleChain(SDValue Op, SDValue Root, ArrayRef<int> Mask,
Mask.equals(8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15,
15))) {
bool Lo = Mask[0] == 0;
unsigned Shuffle = Lo ? X86ISD::UNPCKL : X86ISD::UNPCKH;
if (Depth == 1 && Root->getOpcode() == Shuffle)
return false; // Nothing to do!
MVT ShuffleVT;
switch (Mask.size()) {
case 4: ShuffleVT = MVT::v4i32; break;
case 8: ShuffleVT = MVT::v8i32; break;
case 16: ShuffleVT = MVT::v16i32; break;
case 8: ShuffleVT = MVT::v8i16; break;
case 16: ShuffleVT = MVT::v16i8; break;
};
Op = DAG.getNode(ISD::BITCAST, DL, ShuffleVT, Input);
DCI.AddToWorklist(Op.getNode());
Op = DAG.getNode(Lo ? X86ISD::UNPCKL : X86ISD::UNPCKH, DL, ShuffleVT, Op,
Op);
Op = DAG.getNode(Shuffle, DL, ShuffleVT, Op, Op);
DCI.AddToWorklist(Op.getNode());
DCI.CombineTo(Root.getNode(), DAG.getNode(ISD::BITCAST, DL, RootVT, Op),
/*AddTo*/ true);

4
test/CodeGen/X86/avx-basic.ll
View File

@ -72,9 +72,9 @@ entry:
ret <4 x i64> %shuffle
}
; CHECK: movlhps
; CHECK: vpunpcklqdq
; CHECK-NEXT: vextractf128 $1
; CHECK-NEXT: movlhps
; CHECK-NEXT: vpunpcklqdq
; CHECK-NEXT: vinsertf128 $1
define <4 x i64> @C(<4 x i64> %a, <4 x i64> %b) nounwind uwtable readnone ssp {
entry:

6
test/CodeGen/X86/avx-splat.ll
View File

@ -1,9 +1,7 @@
; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=corei7-avx -mattr=+avx | FileCheck %s
; CHECK: vpunpcklbw %xmm
; CHECK-NEXT: vpunpckhbw %xmm
; CHECK-NEXT: vpshufd $85
; CHECK: vpshufb {{.*}} ## xmm0 = xmm0[5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5]
; CHECK-NEXT: vinsertf128 $1
define <32 x i8> @funcA(<32 x i8> %a) nounwind uwtable readnone ssp {
entry:
@ -21,7 +19,7 @@ entry:
}
; CHECK: vmovq
; CHECK-NEXT: vmovlhps %xmm
; CHECK-NEXT: vpunpcklqdq %xmm
; CHECK-NEXT: vinsertf128 $1
define <4 x i64> @funcC(i64 %q) nounwind uwtable readnone ssp {
entry:

8
test/CodeGen/X86/exedepsfix-broadcast.ll
View File

@ -93,10 +93,10 @@ define <4 x double> @ExeDepsFix_broadcastsd256(<4 x double> %arg, <4 x double> %
; CHECK-LABEL: ExeDepsFix_broadcastsd_inreg
; ExeDepsFix works top down, thus it coalesces vmovlhps domain with
; vandps and there is nothing more you can do to match vmaxpd.
; CHECK: vmovlhps
; CHECK: vandps
; ExeDepsFix works top down, thus it coalesces vpunpcklqdq domain with
; vpand and there is nothing more you can do to match vmaxpd.
; CHECK: vpunpcklqdq
; CHECK: vpand
; CHECK: vmaxpd
; CHECK: ret
define <2 x double> @ExeDepsFix_broadcastsd_inreg(<2 x double> %arg, <2 x double> %arg2, i64 %broadcastvalue) {

61
test/CodeGen/X86/vec_splat-3.ll
View File

@ -75,9 +75,8 @@ define <16 x i8> @shuf_16i8_8(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_8:
; CHECK: punpcklbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $0
; CHECK: pxor %[[X:xmm[0-9]+]], %[[X]]
; CHECK-NEXT: pshufb %[[X]], %xmm0
}
define <16 x i8> @shuf_16i8_9(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -85,9 +84,7 @@ define <16 x i8> @shuf_16i8_9(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_9:
; CHECK: punpcklbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $85
; CHECK: pshufb {{.*}} # xmm0 = xmm0[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]
}
define <16 x i8> @shuf_16i8_10(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -95,9 +92,7 @@ define <16 x i8> @shuf_16i8_10(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_10:
; CHECK: punpcklbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $-86
; CHECK: pshufb {{.*}} # xmm0 = xmm0[2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2]
}
define <16 x i8> @shuf_16i8_11(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -105,9 +100,7 @@ define <16 x i8> @shuf_16i8_11(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_11:
; CHECK: punpcklbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $-1
; CHECK: pshufb {{.*}} # xmm0 = xmm0[3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3]
}
@ -124,9 +117,7 @@ define <16 x i8> @shuf_16i8_13(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_13:
; CHECK: punpcklbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $85
; CHECK: pshufb {{.*}} # xmm0 = xmm0[5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5]
}
define <16 x i8> @shuf_16i8_14(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -134,9 +125,7 @@ define <16 x i8> @shuf_16i8_14(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_14:
; CHECK: punpcklbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $-86
; CHECK: pshufb {{.*}} # xmm0 = xmm0[6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6]
}
define <16 x i8> @shuf_16i8_15(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -144,9 +133,7 @@ define <16 x i8> @shuf_16i8_15(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_15:
; CHECK: punpcklbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $-1
; CHECK: pshufb {{.*}} # xmm0 = xmm0[7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7]
}
define <16 x i8> @shuf_16i8_16(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -154,9 +141,7 @@ define <16 x i8> @shuf_16i8_16(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_16:
; CHECK: punpckhbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $0
; CHECK: pshufb {{.*}} # xmm0 = xmm0[8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8]
}
define <16 x i8> @shuf_16i8_17(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -164,9 +149,7 @@ define <16 x i8> @shuf_16i8_17(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_17:
; CHECK: punpckhbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $85
; CHECK: pshufb {{.*}} # xmm0 = xmm0[9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9]
}
define <16 x i8> @shuf_16i8_18(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -174,9 +157,7 @@ define <16 x i8> @shuf_16i8_18(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_18:
; CHECK: punpckhbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $-86
; CHECK: pshufb {{.*}} # xmm0 = xmm0[10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10]
}
define <16 x i8> @shuf_16i8_19(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -184,9 +165,7 @@ define <16 x i8> @shuf_16i8_19(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_19:
; CHECK: punpckhbw
; CHECK-NEXT: punpcklbw
; CHECK-NEXT: pshufd $-1
; CHECK: pshufb {{.*}} # xmm0 = xmm0[11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11]
}
define <16 x i8> @shuf_16i8_20(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -194,9 +173,7 @@ define <16 x i8> @shuf_16i8_20(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_20:
; CHECK: punpckhbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $0
; CHECK: pshufb {{.*}} # xmm0 = xmm0[12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12]
}
define <16 x i8> @shuf_16i8_21(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -204,9 +181,7 @@ define <16 x i8> @shuf_16i8_21(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_21:
; CHECK: punpckhbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $85
; CHECK: pshufb {{.*}} # xmm0 = xmm0[13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13]
}
define <16 x i8> @shuf_16i8_22(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -214,9 +189,7 @@ define <16 x i8> @shuf_16i8_22(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_22:
; CHECK: punpckhbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $-86
; CHECK: pshufb {{.*}} # xmm0 = xmm0[14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14]
}
define <16 x i8> @shuf_16i8_23(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
@ -224,7 +197,5 @@ define <16 x i8> @shuf_16i8_23(<16 x i8> %T0, <16 x i8> %T1) nounwind readnone {
ret <16 x i8> %tmp6
; CHECK-LABEL: shuf_16i8_23:
; CHECK: punpckhbw
; CHECK-NEXT: punpckhbw
; CHECK-NEXT: pshufd $-1
; CHECK: pshufb {{.*}} # xmm0 = xmm0[15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15]
}