Simon Pilgrim d1592a966b [X86] X86FixupVectorConstantsPass - use scheduler model to avoid regressions (#140028) ...

When attempting to replace a full vector constant load with an instruction that uses a smaller constant, check the scheduler model to ensure the instruction isn't slower.

Throughput must not regress, but allow a small increase in latency based on how much constant data we're saving (I've used a simple estimate of 1 cycle per 128-bits of data saved).

NOTE: this currently ignores hoisted constant loads where the slower instruction might be acceptable.

Fixes #135998

2025-05-28 11:02:37 +01:00

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