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[CIR] [Lowering] [X86_64] VaArg for long double in x86 #1087

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@ChuanqiXu9 ChuanqiXu9 commented Nov 8, 2024

This is the following of #1086. Since I can't create branches to this repo so that I can't start real stacked PRs. After #1086 got merged, the PR will show the real change. This PR is for preview only.

After #1086, when we want to use LongDouble for VAArg, we will be in trouble due to details in X86_64's ABI and this patch tries to address this.

The practical impact the patch is, after this patch, with #1088 and a small following up fix, we can build and run all C's benchmark in SpecCPU 2017. I think it is a milestone.

@ChuanqiXu9 ChuanqiXu9 changed the title Va arg for long double in x86 [CIR] [Lowering] [X86_64] VaArg for long double in x86 Nov 8, 2024
@ChuanqiXu9 ChuanqiXu9 marked this pull request as draft November 8, 2024 03:00
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Since I can't create branches to this repo so that I can't start real stacked PRs

Fixed

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bcardosolopes commented Nov 8, 2024

The practical impact the patch is, after this patch, with #1088 and a small following up fix, we can build and run all C's benchmark in SpecCPU 2017. I think it is a milestone.

Wow, this is amazing. Is that only for x86_64 or did you try other arches?

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I'll take a look after the next PR update (conflicts + stacked approach, or after the other one lands)

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The practical impact the patch is, after this patch, with #1088 and a small following up fix, we can build and run all C's benchmark in SpecCPU 2017. I think it is a milestone.

Wow, this is amazing. Is that only for x86_64 or did you try other arches?

I only tested on X86_64

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Close to create stacked PR

@ChuanqiXu9 ChuanqiXu9 closed this Nov 11, 2024
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@bcardosolopes after I rebased, I noticed the return value of datalayout.getTypeStoreSize(Ty).getFixedValue() goes to 2 from 16 for Long Double. Is this a regression?

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smeenai commented Nov 11, 2024

@bcardosolopes after I rebased, I noticed the return value of datalayout.getTypeStoreSize(Ty).getFixedValue() goes to 2 from 16 for Long Double. Is this a regression?

That might be related to #1089? That reverted a previously landed commit, and there's some discussion there.

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It looks like the case. Thanks.

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Since I can't create branches to this repo so that I can't start real stacked PRs

Fixed

Thanks. BTW, can we add a rule like the upstream that we can only create branches starts with users/.... So that we avoid we push some private branches accidently...

bcardosolopes pushed a commit that referenced this pull request Nov 13, 2024
This patch implements transformations for VAArg in X86_64 ABI **in
shape**. `In shape` means it can't work properly due to the dependent
X86_64 ABI is not robust. e.g., when we want to use VAArg with `long
double`, we need #1087.

This patch literally implement
https://github.com/llvm/llvm-project/blob/d233fedfb0de882353c348cd1ac57dab619efa6d/clang/lib/CodeGen/Targets/X86.cpp#L3015-L3240
in CIR.

There some differences due to the traditional pipeline are converting
AST to LLVM and we're transforming CIR to CIR. And also to get the ABI
Info, I moved `X86_64ABIInfo` to the header.
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3 participants