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[AVR] Optimize 16-bit comparison with constant

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Reviewed By: dylanmckay

Differential Revision: https://reviews.llvm.org/D93976
This commit is contained in:
Ben Shi 2021-01-24 00:38:57 +08:00
parent 77d1393c15
commit 0d8fd96903
3 changed files with 91 additions and 3 deletions
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36
lib/Target/AVR/AVRISelLowering.cpp
View File

@ -455,6 +455,36 @@ static AVRCC::CondCodes intCCToAVRCC(ISD::CondCode CC) {
}
}
/// Returns appropriate CP/CPI/CPC nodes code for the given 8/16-bit operands.
SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS,
SelectionDAG &DAG, SDLoc DL) const {
assert((LHS.getSimpleValueType() == RHS.getSimpleValueType()) &&
"LHS and RHS have different types");
assert(((LHS.getSimpleValueType() == MVT::i16) ||
(LHS.getSimpleValueType() == MVT::i8)) && "invalid comparison type");
SDValue Cmp;
if (LHS.getSimpleValueType() == MVT::i16 && dyn_cast<ConstantSDNode>(RHS)) {
// Generate a CPI/CPC pair if RHS is a 16-bit constant.
SDValue LHSlo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, LHS,
DAG.getIntPtrConstant(0, DL));
SDValue LHShi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, LHS,
DAG.getIntPtrConstant(1, DL));
SDValue RHSlo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, RHS,
DAG.getIntPtrConstant(0, DL));
SDValue RHShi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, RHS,
DAG.getIntPtrConstant(1, DL));
Cmp = DAG.getNode(AVRISD::CMP, DL, MVT::Glue, LHSlo, RHSlo);
Cmp = DAG.getNode(AVRISD::CMPC, DL, MVT::Glue, LHShi, RHShi, Cmp);
} else {
// Generate ordinary 16-bit comparison.
Cmp = DAG.getNode(AVRISD::CMP, DL, MVT::Glue, LHS, RHS);
}
return Cmp;
}
/// Returns appropriate AVR CMP/CMPC nodes and corresponding condition code for
/// the given operands.
SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
@ -567,7 +597,7 @@ SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
DAG.getIntPtrConstant(1, DL));
Cmp = DAG.getNode(AVRISD::TST, DL, MVT::Glue, Top);
} else {
Cmp = DAG.getNode(AVRISD::CMP, DL, MVT::Glue, LHSlo, RHSlo);
Cmp = getAVRCmp(LHSlo, RHSlo, DAG, DL);
Cmp = DAG.getNode(AVRISD::CMPC, DL, MVT::Glue, LHShi, RHShi, Cmp);
}
} else if (VT == MVT::i64) {
@ -605,7 +635,7 @@ SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
DAG.getIntPtrConstant(1, DL));
Cmp = DAG.getNode(AVRISD::TST, DL, MVT::Glue, Top);
} else {
Cmp = DAG.getNode(AVRISD::CMP, DL, MVT::Glue, LHS0, RHS0);
Cmp = getAVRCmp(LHS0, RHS0, DAG, DL);
Cmp = DAG.getNode(AVRISD::CMPC, DL, MVT::Glue, LHS1, RHS1, Cmp);
Cmp = DAG.getNode(AVRISD::CMPC, DL, MVT::Glue, LHS2, RHS2, Cmp);
Cmp = DAG.getNode(AVRISD::CMPC, DL, MVT::Glue, LHS3, RHS3, Cmp);
@ -619,7 +649,7 @@ SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
: DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8,
LHS, DAG.getIntPtrConstant(1, DL)));
} else {
Cmp = DAG.getNode(AVRISD::CMP, DL, MVT::Glue, LHS, RHS);
Cmp = getAVRCmp(LHS, RHS, DAG, DL);
}
} else {
llvm_unreachable("Invalid comparison size");

2
lib/Target/AVR/AVRISelLowering.h
View File

@ -138,6 +138,8 @@ public:
private:
SDValue getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC, SDValue &AVRcc,
SelectionDAG &DAG, SDLoc dl) const;
SDValue getAVRCmp(SDValue LHS, SDValue RHS, SelectionDAG &DAG,
SDLoc dl) const;
SDValue LowerShifts(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerDivRem(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;

56
test/CodeGen/AVR/cmp.ll
View File

@ -36,6 +36,22 @@ if.end:
ret void
}
define void @cmpimm16(i16 %a) {
; CHECK-LABEL: cmpimm16:
; CHECK: cpi
; CHECK-NEXT: cpc
%cmp = icmp eq i16 %a, 4567
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @f3(i16 %a)
br label %if.end
if.else:
tail call void @f4(i16 %a)
br label %if.end
if.end:
ret void
}
declare void @f5(i32)
declare void @f6(i32)
define void @cmp32(i32 %a, i32 %b) {
@ -56,6 +72,24 @@ if.end:
ret void
}
define void @cmpimm32(i32 %a) {
; CHECK-LABEL: cmpimm32:
; CHECK: cpi
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
%cmp = icmp eq i32 %a, 6789343
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @f5(i32 %a)
br label %if.end
if.else:
tail call void @f6(i32 %a)
br label %if.end
if.end:
ret void
}
declare void @f7(i64)
declare void @f8(i64)
define void @cmp64(i64 %a, i64 %b) {
@ -80,6 +114,28 @@ if.end:
ret void
}
define void @cmpimm64(i64 %a) {
; CHECK-LABEL: cmpimm64:
; CHECK: cpi
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
; CHECK-NEXT: cpc
%cmp = icmp eq i64 %a, 234566452
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @f7(i64 %a)
br label %if.end
if.else:
tail call void @f8(i64 %a)
br label %if.end
if.end:
ret void
}
declare void @f9()
declare void @f10()