Handle more than 64 registers - Part 1 #101950
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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This is expected to be zero TP diff, so I will investigate why it is causing 2% regression. Possibly I missed updating something:
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for windows/arm64 crossgen2 collection, here is the distribution. Will take a look |
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The culprit was using |
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src/coreclr/jit/target.h
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| FORCEINLINE explicit operator unsigned int() const | ||
| { | ||
| return (unsigned int)low; | ||
| } |
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This one we ought to remove as well.
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It is currently used only at one place. Ideally, all the *refRegs should be just gpr register set of size 4 bytes, but do not want to mix that change in this PR.
if (ig->igFlags & IGF_BYREF_REGS)
{
// Record the byref regs in front the of the instructions
*castto(id, unsigned*)++ = (unsigned)emitInitByrefRegs;
}
jakobbotsch
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src/coreclr/jit/compiler.hpp
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| #ifdef TARGET_ARM64 | ||
| regNumber regNum = (regNumber)BitScanForward(mask); | ||
| #else | ||
| regNumber regNum = (regNumber)BitOperations::BitScanForward(mask); | ||
| #endif |
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It would be good to avoid these ifdefs by introducing some forwarding BitScanForward in the typedef unsigned __int64 regMaskTP case.
jakobbotsch
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May 10, 2024
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May 10, 2024
Yeah, seems to just be various MSVC regressions due to now having a struct instead of primitive type. Clang seems to do a little bit better. Not much we can do about that I think. |
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We might consider switching Alternatively we could move extra operations to live on some |
I don't mind doing it and was advocate of similar idea back in #98258 because with that, in future, when we add APX support for Intel, enabling the "handling of 64 registers". Edit: With that said, given that #98258 is already out for couple of months now and it is a critical work that is needed to make other progress for SVE, I would like to concentrate on enabling it with as minimal work as needed (just for arm64) and have it enable for other platforms as a follow up PRs once we complete the "predicate register" work. |
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src/coreclr/jit/target.h
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| FORCEINLINE void setLow(uint64_t _low) | ||
| { | ||
| low = _low; | ||
| } |
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I don't think we should have this one (can just assign the full regMaskTP instead)
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Feel free to include it in the follow up
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(FWIW, it seems like bad encapsulation to have low accessible outside this class at all)
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I totally agree with you and was not a fan of having this in the last commit. May be I should just try assigning the whole regMaskTP.
jakobbotsch
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May 10, 2024
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/azp run runtime-coreclr superpmi-diffs |
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/azp run runtime-coreclr superpmi-replay |
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Azure Pipelines successfully started running 1 pipeline(s). |
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May 30, 2024
* Convert regMaskTP for ARM64 to struct with single field * Fix genFirstRegNumFromMaskAndToggle() and genFirstRegNumFromMask() * minor fix * review feedback * fix the TP regression from 1.5% -> 0.5% * Pass by value * jit format * review feedback * Remove FORCEINLINE * Remove setLow()
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The general feedback for #98258 was to come up with smaller PRs concentrated around LSRA. This is part 1 of that.
For Arm64, this PR changes the
typedef unsigned __int64 regMaskTPto `typedefA version of
PopCountandBitOperationshas been added next toregMaskTPstruct definition.Most of the method implementation is pulled from #96196.