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Backport for rust#127286 and rust#127260 #175

Merged
merged 5 commits into from
Jul 5, 2024
Merged

Backport for rust#127286 and rust#127260 #175

merged 5 commits into from
Jul 5, 2024

Commits on Jul 5, 2024

  1. [X86] var-permute-*.ll - check memory address math 

    Expose the memory addressing to simplify checking stack spill/restore manipulation codegen

(cherry picked from commit 8270485)
    @RKSimon @DianQK
    RKSimon authored and DianQK committed Jul 5, 2024
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  2. [X86] matchAddressRecursively - don't fold zext(shl(x,c)) -> shl(zext… 

    …(x),c)) if the pattern has multiple uses

Fixes llvm#97533 crash where we hit a case where the root node had referenced the original zext node, which we then deleted - hopefully I can come up with a better solution, but the codegen changes don't look too bad atm (pulls out a shift from some complex LEA nodes that shared the scaled index).

(cherry picked from commit e975ff0)
    @RKSimon @DianQK
    RKSimon authored and DianQK committed Jul 5, 2024
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  3. [Mem2Reg] Add some single store tests (NFC) 

    For llvm#97702.

(cherry picked from commit e7bfd4d)
    @nikic @DianQK
    nikic authored and DianQK committed Jul 5, 2024
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  4. [Mem2Reg] Don't use single store optimization for potentially poison … 

    …value (llvm#97711)

If there is a single store, then loads must either load the stored value
or uninitialized memory (undef). If the stored value may be poison, then
replacing an uninitialized memory load with it would be incorrect. Fall
back to the generic code in that case.

This PR only fixes the case where there is a literal poison store -- the
case where the value is non-trivially poison will still get miscompiled
by phi simplification later, see llvm#96631.

Fixes llvm#97702.

(cherry picked from commit f58930f)
    @nikic @DianQK
    nikic authored and DianQK committed Jul 5, 2024
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  5. [Mem2Reg] Always allow single-store optimization for dominating stores 

    In llvm#97711 the single-store optimization was disabled for the case
where the value is potentially poison, as this may produce incorrect
results for loads of uninitialized memory.

However, this resulted in compile-time regressions. Address these
by still allowing the single-store optimization to occur in cases
where the store dominates the load, as we know that such a load
will always read initialized memory.

(cherry picked from commit daaea12)
    @nikic @DianQK
    nikic authored and DianQK committed Jul 5, 2024
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