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[DAG] Promote ADDCARRY / SUBCARRY 

Add missing case that was not implemented yet.

Differential Revision: https://reviews.llvm.org/D38942

llvm-svn: 320567
This commit is contained in:
Roger Ferrer Ibanez 2017-12-13 10:45:21 +00:00
parent b41dbbe325
commit e8d4e88bab
2 changed files with 84 additions and 1 deletions
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25
llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
View File

@ -772,7 +772,30 @@ SDValue DAGTypeLegalizer::PromoteIntRes_UADDSUBO(SDNode *N, unsigned ResNo) {
SDValue DAGTypeLegalizer::PromoteIntRes_ADDSUBCARRY(SDNode *N, unsigned ResNo) {
if (ResNo == 1)
return PromoteIntRes_Overflow(N);
llvm_unreachable("Not implemented");
// We need to sign-extend the operands so the carry value computed by the
// wide operation will be equivalent to the carry value computed by the
// narrow operation.
// An ADDCARRY can generate carry only if any of the operands has its
// most significant bit set. Sign extension propagates the most significant
// bit into the higher bits which means the extra bit that the narrow
// addition would need (i.e. the carry) will be propagated through the higher
// bits of the wide addition.
// A SUBCARRY can generate borrow only if LHS < RHS and this property will be
// preserved by sign extension.
SDValue LHS = SExtPromotedInteger(N->getOperand(0));
SDValue RHS = SExtPromotedInteger(N->getOperand(1));
EVT ValueVTs[] = {LHS.getValueType(), N->getValueType(1)};
// Do the arithmetic in the wide type.
SDValue Res = DAG.getNode(N->getOpcode(), SDLoc(N), DAG.getVTList(ValueVTs),
LHS, RHS, N->getOperand(2));
// Update the users of the original carry/borrow value.
ReplaceValueWith(SDValue(N, 1), Res.getValue(1));
return SDValue(Res.getNode(), 0);
}
SDValue DAGTypeLegalizer::PromoteIntRes_XMULO(SDNode *N, unsigned ResNo) {

60
llvm/test/CodeGen/ARM/addsubcarry-promotion.ll Normal file
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@ -0,0 +1,60 @@
; RUN: llc -O2 -mtriple armv7a < %s | FileCheck --check-prefix=ARM %s
; RUN: llc -O2 -mtriple thumbv6m < %s | FileCheck --check-prefix=THUMB1 %s
; RUN: llc -O2 -mtriple thumbv8m.base < %s | FileCheck --check-prefix=THUMB1 %s
; RUN: llc -O2 -mtriple thumbv7a < %s | FileCheck --check-prefix=THUMB %s
; RUN: llc -O2 -mtriple thumbv8m.main < %s | FileCheck --check-prefix=THUMB %s
define void @fn1(i32 %a, i32 %b, i32 %c) local_unnamed_addr #0 {
entry:
; ARM: rsb r2, r2, #1
; ARM: adds r0, r1, r0
; ARM: movw r1, #65535
; ARM: sxth r2, r2
; ARM: adc r0, r2, #0
; ARM: tst r0, r1
; ARM: bxeq lr
; ARM: .LBB0_1:
; ARM: b .LBB0_1
; THUMB1: movs r3, #1
; THUMB1: subs r2, r3, r2
; THUMB1: sxth r2, r2
; THUMB1: movs r3, #0
; THUMB1: adds r0, r1, r0
; THUMB1: adcs r3, r2
; THUMB1: lsls r0, r3, #16
; THUMB1: beq .LBB0_2
; THUMB1: .LBB0_1:
; THUMB1: b .LBB0_1
; THUMB: rsb.w r2, r2, #1
; THUMB: adds r0, r0, r1
; THUMB: sxth r2, r2
; THUMB: adc r0, r2, #0
; THUMB: lsls r0, r0, #16
; THUMB: it eq
; THUMB: bxeq lr
; THUMB: .LBB0_1:
; THUMB: b .LBB0_1
%add = add i32 %b, %a
%cmp = icmp ult i32 %add, %b
%conv = zext i1 %cmp to i32
%sub = sub i32 1, %c
%add1 = add i32 %sub, %conv
%conv2 = trunc i32 %add1 to i16
%tobool = icmp eq i16 %conv2, 0
br i1 %tobool, label %if.end, label %for.cond.preheader
for.cond.preheader: ; preds = %entry
br label %for.cond
for.cond: ; preds = %for.cond.preheader, %for.cond
br label %for.cond
if.end: ; preds = %entry
ret void
}