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[SystemZ] Fix addcarry of usubo (PR42512) 

Only custom lower uaddo+addcarry or usubo+subcarry chains and leave
mixtures like usubo+addcarry or uaddo+subcarry to the generic
legalizer. Otherwise we run into issues because SystemZ uses
different CC values for carries and borrows.

Fixes https://bugs.llvm.org/show_bug.cgi?id=42512.

Differential Revision: https://reviews.llvm.org/D64213

llvm-svn: 365242
This commit is contained in:
Nikita Popov 2019-07-05 20:35:11 +00:00
parent e7e23e3e91
commit a2a09cb606
2 changed files with 29 additions and 0 deletions
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6
llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
View File

@ -3449,11 +3449,17 @@ SDValue SystemZTargetLowering::lowerADDSUBCARRY(SDValue Op,
switch (Op.getOpcode()) {
default: llvm_unreachable("Unknown instruction!");
case ISD::ADDCARRY:
if (Carry.getOpcode() != ISD::UADDO && Carry.getOpcode() != ISD::ADDCARRY)
return SDValue();
BaseOp = SystemZISD::ADDCARRY;
CCValid = SystemZ::CCMASK_LOGICAL;
CCMask = SystemZ::CCMASK_LOGICAL_CARRY;
break;
case ISD::SUBCARRY:
if (Carry.getOpcode() != ISD::USUBO && Carry.getOpcode() != ISD::SUBCARRY)
return SDValue();
BaseOp = SystemZISD::SUBCARRY;
CCValid = SystemZ::CCMASK_LOGICAL;
CCMask = SystemZ::CCMASK_LOGICAL_BORROW;

23
llvm/test/CodeGen/SystemZ/pr42512.ll Normal file
View File

@ -0,0 +1,23 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
define i8 @test(i8 %x) {
; CHECK-LABEL: test:
; CHECK: # %bb.0:
; CHECK-NEXT: slgfi %r0, 1
; CHECK-NEXT: ipm %r0
; CHECK-NEXT: afi %r0, -536870912
; CHECK-NEXT: srl %r0, 31
; CHECK-NEXT: ar %r2, %r0
; CHECK-NEXT: br %r14
%usubo = tail call { i64, i1 } @llvm.usub.with.overflow.i64(i64 undef, i64 1)
%ov = extractvalue { i64, i1 } %usubo, 1
%ovext = zext i1 %ov to i8
%ret = add i8 %x, %ovext
ret i8 %ret
}
; Function Attrs: nounwind readnone speculatable
declare { i64, i1 } @llvm.usub.with.overflow.i64(i64, i64) #0
attributes #0 = { nounwind readnone speculatable }