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[AArch64] Combine to UMULL if top bits are known zero
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Given mul(zext(a), b), we can convert to a umull so long as we know that
the top bits of b are zero. This uses MaskedValueIsZero to detect that
case for NEON UMULL patterns.

Differential Revision: https://reviews.llvm.org/D140287
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@davemgreen
davemgreen committed Dec 20, 2022
1 parent ecaab10 commit 3c0c24e
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Showing 3 changed files with 74 additions and 72 deletions.
34 changes: 34 additions & 0 deletions llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
View file
Expand Up @@ -4567,8 +4567,42 @@ static unsigned selectUmullSmull(SDNode *&N0, SDNode *&N1, SelectionDAG &DAG,
return AArch64ISD::SMULL;
}
}

// Select UMULL if we can replace the other operand with an extend.
if (IsN0ZExt || IsN1ZExt) {
EVT VT = N0->getValueType(0);
APInt Mask = APInt::getHighBitsSet(VT.getScalarSizeInBits(),
VT.getScalarSizeInBits() / 2);
if (DAG.MaskedValueIsZero(SDValue(IsN0ZExt ? N1 : N0, 0), Mask)) {
EVT HalfVT;
switch (VT.getSimpleVT().SimpleTy) {
case MVT::v2i64:
HalfVT = MVT::v2i32;
break;
case MVT::v4i32:
HalfVT = MVT::v4i16;
break;
case MVT::v8i16:
HalfVT = MVT::v8i8;
break;
default:
return 0;
}
// Truncate and then extend the result.
SDValue NewExt = DAG.getNode(ISD::TRUNCATE, DL, HalfVT,
SDValue(IsN0ZExt ? N1 : N0, 0));
NewExt = DAG.getZExtOrTrunc(NewExt, DL, VT);
if (IsN0ZExt)
N1 = NewExt.getNode();
else
N0 = NewExt.getNode();
return AArch64ISD::UMULL;
}
}

if (!IsN1SExt && !IsN1ZExt)
return 0;

// Look for (s/zext A + s/zext B) * (s/zext C). We want to turn these
// into (s/zext A * s/zext C) + (s/zext B * s/zext C)
if (IsN1SExt && isAddSubSExt(N0, DAG)) {
Expand Down
20 changes: 8 additions & 12 deletions llvm/test/CodeGen/AArch64/aarch64-dup-ext.ll
View file
Expand Up @@ -116,17 +116,13 @@ entry:
define <2 x i64> @dupzext_v2i16_v2i64(i16 %src, <2 x i16> %b) {
; CHECK-LABEL: dupzext_v2i16_v2i64:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi d1, #0x00ffff0000ffff
; CHECK-NEXT: // kill: def $w0 killed $w0 def $x0
; CHECK-NEXT: and x8, x0, #0xffff
; CHECK-NEXT: movi d1, #0x00ffff0000ffff
; CHECK-NEXT: dup v2.2d, x8
; CHECK-NEXT: and v0.8b, v0.8b, v1.8b
; CHECK-NEXT: ushll v0.2d, v0.2s, #0
; CHECK-NEXT: fmov x9, d0
; CHECK-NEXT: mov x10, v0.d[1]
; CHECK-NEXT: mul x9, x8, x9
; CHECK-NEXT: mul x8, x8, x10
; CHECK-NEXT: fmov d0, x9
; CHECK-NEXT: mov v0.d[1], x8
; CHECK-NEXT: xtn v2.2s, v2.2d
; CHECK-NEXT: umull v0.2d, v2.2s, v0.2s
; CHECK-NEXT: ret
entry:
%in = zext i16 %src to i64
Expand Down Expand Up @@ -225,12 +221,12 @@ define void @typei1_orig(i64 %a, ptr %p, ptr %q) {
define <8 x i16> @typei1_v8i1_v8i16(i1 %src, <8 x i1> %b) {
; CHECK-LABEL: typei1_v8i1_v8i16:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v1.8b, #1
; CHECK-NEXT: and w8, w0, #0x1
; CHECK-NEXT: movi v1.8b, #1
; CHECK-NEXT: dup v2.8h, w8
; CHECK-NEXT: and v0.8b, v0.8b, v1.8b
; CHECK-NEXT: dup v1.8h, w8
; CHECK-NEXT: ushll v0.8h, v0.8b, #0
; CHECK-NEXT: mul v0.8h, v1.8h, v0.8h
; CHECK-NEXT: xtn v2.8b, v2.8h
; CHECK-NEXT: umull v0.8h, v2.8b, v0.8b
; CHECK-NEXT: ret
entry:
%in = zext i1 %src to i16
Expand Down
92 changes: 32 additions & 60 deletions llvm/test/CodeGen/AArch64/aarch64-smull.ll
View file
Expand Up @@ -932,9 +932,9 @@ define <4 x i64> @amull2_i32(<4 x i32> %arg1, <4 x i32> %arg2) {
define <8 x i16> @umull_and_v8i16(<8 x i8> %src1, <8 x i16> %src2) {
; CHECK-LABEL: umull_and_v8i16:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: ushll v0.8h, v0.8b, #0
; CHECK-NEXT: bic v1.8h, #255, lsl #8
; CHECK-NEXT: mul v0.8h, v0.8h, v1.8h
; CHECK-NEXT: xtn v1.8b, v1.8h
; CHECK-NEXT: umull v0.8h, v0.8b, v1.8b
; CHECK-NEXT: ret
entry:
%in1 = zext <8 x i8> %src1 to <8 x i16>
Expand All @@ -946,9 +946,9 @@ entry:
define <8 x i16> @umull_and_v8i16_c(<8 x i8> %src1, <8 x i16> %src2) {
; CHECK-LABEL: umull_and_v8i16_c:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: ushll v0.8h, v0.8b, #0
; CHECK-NEXT: bic v1.8h, #255, lsl #8
; CHECK-NEXT: mul v0.8h, v1.8h, v0.8h
; CHECK-NEXT: xtn v1.8b, v1.8h
; CHECK-NEXT: umull v0.8h, v1.8b, v0.8b
; CHECK-NEXT: ret
entry:
%in1 = zext <8 x i8> %src1 to <8 x i16>
Expand Down Expand Up @@ -989,9 +989,9 @@ define <8 x i16> @umull_smaller_v8i16(<8 x i4> %src1, <8 x i16> %src2) {
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v2.8b, #15
; CHECK-NEXT: bic v1.8h, #255, lsl #8
; CHECK-NEXT: xtn v1.8b, v1.8h
; CHECK-NEXT: and v0.8b, v0.8b, v2.8b
; CHECK-NEXT: ushll v0.8h, v0.8b, #0
; CHECK-NEXT: mul v0.8h, v0.8h, v1.8h
; CHECK-NEXT: umull v0.8h, v0.8b, v1.8b
; CHECK-NEXT: ret
entry:
%in1 = zext <8 x i4> %src1 to <8 x i16>
Expand All @@ -1004,9 +1004,9 @@ define <4 x i32> @umull_and_v4i32(<4 x i16> %src1, <4 x i32> %src2) {
; CHECK-LABEL: umull_and_v4i32:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v2.2d, #0x0000ff000000ff
; CHECK-NEXT: ushll v0.4s, v0.4h, #0
; CHECK-NEXT: and v1.16b, v1.16b, v2.16b
; CHECK-NEXT: mul v0.4s, v0.4s, v1.4s
; CHECK-NEXT: xtn v1.4h, v1.4s
; CHECK-NEXT: umull v0.4s, v0.4h, v1.4h
; CHECK-NEXT: ret
entry:
%in1 = zext <4 x i16> %src1 to <4 x i32>
Expand All @@ -1019,12 +1019,13 @@ define <8 x i32> @umull_and_v8i32(<8 x i16> %src1, <8 x i32> %src2) {
; CHECK-LABEL: umull_and_v8i32:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v3.2d, #0x0000ff000000ff
; CHECK-NEXT: ushll v4.4s, v0.4h, #0
; CHECK-NEXT: ushll2 v0.4s, v0.8h, #0
; CHECK-NEXT: and v5.16b, v1.16b, v3.16b
; CHECK-NEXT: and v1.16b, v2.16b, v3.16b
; CHECK-NEXT: mul v1.4s, v0.4s, v1.4s
; CHECK-NEXT: mul v0.4s, v4.4s, v5.4s
; CHECK-NEXT: ext v4.16b, v0.16b, v0.16b, #8
; CHECK-NEXT: and v2.16b, v2.16b, v3.16b
; CHECK-NEXT: and v1.16b, v1.16b, v3.16b
; CHECK-NEXT: xtn v1.4h, v1.4s
; CHECK-NEXT: xtn v2.4h, v2.4s
; CHECK-NEXT: umull v0.4s, v0.4h, v1.4h
; CHECK-NEXT: umull v1.4s, v4.4h, v2.4h
; CHECK-NEXT: ret
entry:
%in1 = zext <8 x i16> %src1 to <8 x i32>
Expand All @@ -1037,11 +1038,11 @@ define <8 x i32> @umull_and_v8i32_dup(<8 x i16> %src1, i32 %src2) {
; CHECK-LABEL: umull_and_v8i32_dup:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: ushll v1.4s, v0.4h, #0
; CHECK-NEXT: ushll2 v3.4s, v0.8h, #0
; CHECK-NEXT: ext v1.16b, v0.16b, v0.16b, #8
; CHECK-NEXT: dup v2.4s, w8
; CHECK-NEXT: mul v0.4s, v1.4s, v2.4s
; CHECK-NEXT: mul v1.4s, v3.4s, v2.4s
; CHECK-NEXT: xtn v2.4h, v2.4s
; CHECK-NEXT: umull v0.4s, v0.4h, v2.4h
; CHECK-NEXT: umull v1.4s, v1.4h, v2.4h
; CHECK-NEXT: ret
entry:
%in1 = zext <8 x i16> %src1 to <8 x i32>
Expand All @@ -1056,16 +1057,9 @@ define <2 x i64> @umull_and_v2i64(<2 x i32> %src1, <2 x i64> %src2) {
; CHECK-LABEL: umull_and_v2i64:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v2.2d, #0x000000000000ff
; CHECK-NEXT: ushll v0.2d, v0.2s, #0
; CHECK-NEXT: fmov x10, d0
; CHECK-NEXT: and v1.16b, v1.16b, v2.16b
; CHECK-NEXT: fmov x9, d1
; CHECK-NEXT: mov x8, v1.d[1]
; CHECK-NEXT: mov x11, v0.d[1]
; CHECK-NEXT: mul x9, x10, x9
; CHECK-NEXT: mul x8, x11, x8
; CHECK-NEXT: fmov d0, x9
; CHECK-NEXT: mov v0.d[1], x8
; CHECK-NEXT: xtn v1.2s, v1.2d
; CHECK-NEXT: umull v0.2d, v0.2s, v1.2s
; CHECK-NEXT: ret
entry:
%in1 = zext <2 x i32> %src1 to <2 x i64>
Expand All @@ -1078,26 +1072,13 @@ define <4 x i64> @umull_and_v4i64(<4 x i32> %src1, <4 x i64> %src2) {
; CHECK-LABEL: umull_and_v4i64:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: movi v3.2d, #0x000000000000ff
; CHECK-NEXT: ushll v4.2d, v0.2s, #0
; CHECK-NEXT: ushll2 v0.2d, v0.4s, #0
; CHECK-NEXT: fmov x14, d4
; CHECK-NEXT: ext v4.16b, v0.16b, v0.16b, #8
; CHECK-NEXT: and v2.16b, v2.16b, v3.16b
; CHECK-NEXT: fmov x11, d0
; CHECK-NEXT: mov x9, v0.d[1]
; CHECK-NEXT: and v0.16b, v1.16b, v3.16b
; CHECK-NEXT: fmov x10, d2
; CHECK-NEXT: fmov x13, d0
; CHECK-NEXT: mov x8, v2.d[1]
; CHECK-NEXT: mov x12, v0.d[1]
; CHECK-NEXT: mul x10, x11, x10
; CHECK-NEXT: mov x15, v4.d[1]
; CHECK-NEXT: mul x11, x14, x13
; CHECK-NEXT: mul x8, x9, x8
; CHECK-NEXT: fmov d1, x10
; CHECK-NEXT: mul x9, x15, x12
; CHECK-NEXT: fmov d0, x11
; CHECK-NEXT: mov v1.d[1], x8
; CHECK-NEXT: mov v0.d[1], x9
; CHECK-NEXT: and v1.16b, v1.16b, v3.16b
; CHECK-NEXT: xtn v1.2s, v1.2d
; CHECK-NEXT: xtn v2.2s, v2.2d
; CHECK-NEXT: umull v0.2d, v0.2s, v1.2s
; CHECK-NEXT: umull v1.2d, v4.2s, v2.2s
; CHECK-NEXT: ret
entry:
%in1 = zext <4 x i32> %src1 to <4 x i64>
Expand All @@ -1109,21 +1090,12 @@ entry:
define <4 x i64> @umull_and_v4i64_dup(<4 x i32> %src1, i64 %src2) {
; CHECK-LABEL: umull_and_v4i64_dup:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: ushll2 v1.2d, v0.4s, #0
; CHECK-NEXT: and x8, x0, #0xff
; CHECK-NEXT: ushll v0.2d, v0.2s, #0
; CHECK-NEXT: fmov x9, d1
; CHECK-NEXT: fmov x11, d0
; CHECK-NEXT: mov x10, v1.d[1]
; CHECK-NEXT: mov x12, v0.d[1]
; CHECK-NEXT: mul x9, x9, x8
; CHECK-NEXT: mul x11, x11, x8
; CHECK-NEXT: mul x10, x10, x8
; CHECK-NEXT: mul x8, x12, x8
; CHECK-NEXT: fmov d1, x9
; CHECK-NEXT: fmov d0, x11
; CHECK-NEXT: mov v1.d[1], x10
; CHECK-NEXT: mov v0.d[1], x8
; CHECK-NEXT: ext v1.16b, v0.16b, v0.16b, #8
; CHECK-NEXT: dup v2.2d, x8
; CHECK-NEXT: xtn v2.2s, v2.2d
; CHECK-NEXT: umull v0.2d, v0.2s, v2.2s
; CHECK-NEXT: umull v1.2d, v1.2s, v2.2s
; CHECK-NEXT: ret
entry:
%in1 = zext <4 x i32> %src1 to <4 x i64>
Expand Down

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