improve asm copy propagation for MOVE instruction #6641
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CodSpeed Performance ReportMerging #6641 will not alter performanceComparing Summary
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| VirtualOp::ADD(dest, opd1, opd2) => { | ||
| // We don't look for the first operand being a constant and the second | ||
| // one a base register. Such patterns must be canonicalised prior. | ||
| if let Some(&RegContents::Constant(c2)) = reg_contents.get(opd2) { |
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Am I correct in understanding that this is a bug fix? (unrelated to MOVs). We're missing an optimization opportunity here
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This should be the same code, but with a if let to accommodate the fact that this runs inside a retain_mut now.
| }, | ||
| VirtualOp::MOVE(dest, src) => { | ||
| let ver = get_def_version(&latest_version, src); | ||
| if let Some(RegContents::BaseOffset(src, 0)) = reg_contents.get(src) { |
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are you trying to catch something like
a = b
b = a
?? Not sure I understand what is it that you're trying to optimize, and why the existing copy propagation in the assembly generator doesn't apply.
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For example, from the configurable_const test:
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On a = b, this match arm does two things:
1 - first, it indeed checks if a and b are already the same, and it removes the instruction;
2 - but it also propagates that b and a are the same for future optimizations.
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Breaking*orNew Featurelabels where relevant.