forked from OSchip/llvm-project
075e5a2e2b
It caused PR34564. > This is a preparatory step for D34515 and also is being recommitted as its > first version caused PR34045. > > This change: > - makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32 > - lowering is done by first converting the boolean value into the carry flag > using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value > using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two > operations does the actual addition. > - for subtraction, given that ISD::SUBCARRY second result is actually a > borrow, we need to invert the value of the second operand and result before > and after using ARMISD::SUBE. We need to invert the carry result of > ARMISD::SUBE to preserve the semantics. > - given that the generic combiner may lower ISD::ADDCARRY and > ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering > as well otherwise i64 operations now would require branches. This implies > updating the corresponding test for unsigned. > - add new combiner to remove the redundant conversions from/to carry flags > to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C > - fixes PR34045 > > Differential Revision: https://reviews.llvm.org/D35192 llvm-svn: 312980 |
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