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Adding the missed optimisation
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@jf-botto
jf-botto committed Sep 28, 2024
1 parent 1393eb5 commit c2352ab
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Showing 3 changed files with 55 additions and 33 deletions.
33 changes: 33 additions & 0 deletions llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4299,6 +4299,36 @@ static SDValue LowerPREFETCH(SDValue Op, SelectionDAG &DAG) {
Op.getOperand(1));
}

// Converts SETCC (AND X Y) Z ULT -> SETCC (AND X (Y & ~(Z - 1)) 0 EQ when Y is
// a power of 2. This is then lowered to ANDS X (Y & ~(Z - 1)) which produces a
// better opt with EmitComparison.
static void SimplifySetCCIntoEq(ISD::CondCode &CC, SDValue &LHS, SDValue &RHS,
SelectionDAG &DAG, const SDLoc DL) {
switch (CC) {
default:
break;
case ISD::SETULT:
if (LHS.getOpcode() == ISD::AND) {
ConstantSDNode *LHSAndConst = dyn_cast<ConstantSDNode>(LHS.getOperand(1));
ConstantSDNode *RHSConst = dyn_cast<ConstantSDNode>(RHS);
if (LHSAndConst && RHSConst && LHSAndConst->hasOneUse() &&
RHSConst->hasOneUse()) {
uint64_t LHSAndConstValue = LHSAndConst->getZExtValue();
uint64_t RHSConstValue = RHSConst->getZExtValue();
if (isPowerOf2_64(RHSConstValue)) {
uint64_t NewMaskValue = LHSAndConstValue & ~(RHSConstValue - 1);
LHS = DAG.getNode(
ISD::AND, DL, LHS.getValueType(), LHS.getOperand(0),
DAG.getConstant(NewMaskValue, DL, LHS.getValueType()));
RHS = DAG.getConstant(0, DL, RHS.getValueType());
CC = ISD::SETEQ;
}
}
}
break;
}
}

SDValue AArch64TargetLowering::LowerFP_EXTEND(SDValue Op,
SelectionDAG &DAG) const {
EVT VT = Op.getValueType();
Expand Down Expand Up @@ -10587,6 +10617,9 @@ SDValue AArch64TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) const {
}

if (LHS.getValueType().isInteger()) {

SimplifySetCCIntoEq(CC, LHS, RHS, DAG, dl);

SDValue CCVal;
SDValue Cmp = getAArch64Cmp(
LHS, RHS, ISD::getSetCCInverse(CC, LHS.getValueType()), CCVal, DAG, dl);
Expand Down
30 changes: 12 additions & 18 deletions llvm/test/CodeGen/AArch64/pr102703.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,8 @@
define i1 @lt2_u8(i8 %0) {
; CHECK-LABEL: lt2_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #2
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xfe
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 2
ret i1 %2
Expand All @@ -15,9 +14,8 @@ define i1 @lt2_u8(i8 %0) {
define i1 @lt4_u8(i8 %0) {
; CHECK-LABEL: lt4_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #4
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xfc
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 4
ret i1 %2
Expand All @@ -26,9 +24,8 @@ define i1 @lt4_u8(i8 %0) {
define i1 @lt8_u8(i8 %0) {
; CHECK-LABEL: lt8_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #8
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xf8
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 8
ret i1 %2
Expand All @@ -37,9 +34,8 @@ define i1 @lt8_u8(i8 %0) {
define i1 @lt16_u8(i8 %0) {
; CHECK-LABEL: lt16_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #16
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xf0
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 16
ret i1 %2
Expand All @@ -48,9 +44,8 @@ define i1 @lt16_u8(i8 %0) {
define i1 @lt32_u8(i8 %0) {
; CHECK-LABEL: lt32_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #32
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xe0
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 32
ret i1 %2
Expand All @@ -59,9 +54,8 @@ define i1 @lt32_u8(i8 %0) {
define i1 @lt64_u8(i8 %0) {
; CHECK-LABEL: lt64_u8:
; CHECK: // %bb.0:
; CHECK-NEXT: and w8, w0, #0xff
; CHECK-NEXT: cmp w8, #64
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w0, #0xc0
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%2 = icmp ult i8 %0, 64
ret i1 %2
Expand Down
25 changes: 10 additions & 15 deletions llvm/test/CodeGen/AArch64/signed-truncation-check.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -287,9 +287,8 @@ define i1 @add_ultcmp_bad_i16_i8_add(i16 %x, i16 %y) nounwind {
; CHECK-LABEL: add_ultcmp_bad_i16_i8_add:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w0, w1
; CHECK-NEXT: and w8, w8, #0xffff
; CHECK-NEXT: cmp w8, #256
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w8, #0xff00
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%tmp0 = add i16 %x, %y
%tmp1 = icmp ult i16 %tmp0, 256 ; 1U << 8
Expand Down Expand Up @@ -328,9 +327,8 @@ define i1 @add_ultcmp_bad_i16_i8_c0notpoweroftwo(i16 %x) nounwind {
; CHECK-LABEL: add_ultcmp_bad_i16_i8_c0notpoweroftwo:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w0, #192
; CHECK-NEXT: and w8, w8, #0xffff
; CHECK-NEXT: cmp w8, #256
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w8, #0xff00
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%tmp0 = add i16 %x, 192 ; (1U << (8-1)) + (1U << (8-1-1))
%tmp1 = icmp ult i16 %tmp0, 256 ; 1U << 8
Expand All @@ -356,9 +354,8 @@ define i1 @add_ultcmp_bad_i16_i8_magic(i16 %x) nounwind {
; CHECK-LABEL: add_ultcmp_bad_i16_i8_magic:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w0, #64
; CHECK-NEXT: and w8, w8, #0xffff
; CHECK-NEXT: cmp w8, #256
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w8, #0xff00
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%tmp0 = add i16 %x, 64 ; 1U << (8-1-1)
%tmp1 = icmp ult i16 %tmp0, 256 ; 1U << 8
Expand All @@ -370,9 +367,8 @@ define i1 @add_ultcmp_bad_i16_i4(i16 %x) nounwind {
; CHECK-LABEL: add_ultcmp_bad_i16_i4:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w0, #8
; CHECK-NEXT: and w8, w8, #0xffff
; CHECK-NEXT: cmp w8, #16
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w8, #0xfff0
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%tmp0 = add i16 %x, 8 ; 1U << (4-1)
%tmp1 = icmp ult i16 %tmp0, 16 ; 1U << 4
Expand All @@ -384,9 +380,8 @@ define i1 @add_ultcmp_bad_i24_i8(i24 %x) nounwind {
; CHECK-LABEL: add_ultcmp_bad_i24_i8:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w0, #128
; CHECK-NEXT: and w8, w8, #0xffffff
; CHECK-NEXT: cmp w8, #256
; CHECK-NEXT: cset w0, lo
; CHECK-NEXT: tst w8, #0xffff00
; CHECK-NEXT: cset w0, eq
; CHECK-NEXT: ret
%tmp0 = add i24 %x, 128 ; 1U << (8-1)
%tmp1 = icmp ult i24 %tmp0, 256 ; 1U << 8
Expand Down

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