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[RISCV] Miscompilation of inline assembly #100779
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@llvm/issue-subscribers-backend-risc-v Author: None (shkoo)
It looks like LLC is miscompiling passing a register load to inline assembly:
Running llc on this crashes with assertions enabled (https://godbolt.org/z/1zWaoxKKE). Without assertions, it generates incorrect code (https://godbolt.org/z/43c4W44nY); notice that it silently discards the load of the low bits of using_inout: # @<!-- -->using_inout
lui a0, %hi(_ZN5repro9MY_BUFFER17hb0f674501d5980a6E)
ecall
ret This regression looks like it happened somewhere between llvm 17 (https://godbolt.org/z/o6eWGx68o) and llvm 18 (https://godbolt.org/z/fMMd9Gf3W). For more background, see rust-lang/rust#128212 |
…s register in a non-memory constraint. If the register is used by a non-memory constraint we should disable the fold. Otherwise, we may leave CommonOffset unassigned. Fixes llvm#100779.
/cherry-pick c901b73 |
…s register in a non-memory constraint. (llvm#100790) If the register is used by a non-memory constraint we should disable the fold. Otherwise, we may leave CommonOffset unassigned. Fixes llvm#100779. (cherry picked from commit c901b73)
/pull-request #100843 |
…s register in a non-memory constraint. (llvm#100790) If the register is used by a non-memory constraint we should disable the fold. Otherwise, we may leave CommonOffset unassigned. Fixes llvm#100779. (cherry picked from commit c901b73)
It looks like LLC is miscompiling passing a register load to inline assembly:
Running llc on this crashes with assertions enabled (https://godbolt.org/z/1zWaoxKKE).
Without assertions, it generates incorrect code (https://godbolt.org/z/43c4W44nY); notice that it silently discards the load of the low bits of
_ZN5repro9MY_BUFFER17hb0f674501d5980a6E
causing an incorrect value to be loaded in registera0
:This regression looks like it happened somewhere between llvm 17 (https://godbolt.org/z/o6eWGx68o) and llvm 18 (https://godbolt.org/z/fMMd9Gf3W).
For more background, see rust-lang/rust#128212
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