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IRGen: fix swifterror attribute mismatch for WebAssembly #39359

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Merged
merged 1 commit into from
May 28, 2022
Merged

IRGen: fix swifterror attribute mismatch for WebAssembly #39359

merged 1 commit into from
May 28, 2022

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MaxDesiatov
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On WebAssembly, tail optional arguments are not allowed because Wasm requires callee and caller signature to be the same. So LLVM adds dummy arguments for swiftself and swifterror. If there is swiftself but is no swifterror in a swiftcc function or invocation, then LLVM adds dummy swifterror parameter or argument. To count up how many dummy arguments should be added, we need to mark it as swifterror even though it's not in register.

Related to SR-9307.

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@kateinoigakukun I'm following your previous changes and comments here. I hope the description makes sense. Do you think there's a way to add any tests for this, or will tests require the driver change to be merged first to enable testing the WASI/Wasm triple?

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@swift-ci please smoke test

@MaxDesiatov MaxDesiatov marked this pull request as ready for review September 18, 2021 20:32
@MaxDesiatov MaxDesiatov mentioned this pull request Sep 18, 2021
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@kateinoigakukun
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kateinoigakukun commented Sep 18, 2021 •
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@MaxDesiatov IRGen things can be tested without the driver change. (But we need to fix the current CI failure at first. Now I'm working on it)

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@kateinoigakukun now that community CI failure is fixed, how do we set IGM.ShouldUseSwiftError to different values for testing? Or having another look at the diff, maybe we should modify isSwiftErrorLoweredInRegister function instead here?

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@swift-ci please smoke test

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DougGregor commented Dec 10, 2021 •
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(EDIT: Re-running Windows tests due to an unrelated error)

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DougGregor requested changes Dec 10, 2021
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Can you add an IRGen test to verify that the extra parameter is there for wasm?

lib/IRGen/IRGenModule.cpp
// This mismatch of attributes would be issue when lowering to WebAssembly.
// While lowering, LLVM counts how many dummy params are necessary to match
// callee and caller signature. So we need to add them correctly.
if (functionName == "swift_willThrow") {
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Could we model this with a flag in the RuntimeFunctions.def DSL? The specific function name check feels brittle.

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@MaxDesiatov MaxDesiatov Dec 11, 2021 •
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This would require some refinement of such DSL, right? Currently it doesn't allow setting attributes on parameters. What would be the best way to specify these attributes in RuntimeFunctions.def then?

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Sorry, I missed your reply in my flood of GitHub notifications. I think we can do this refactoring, but it shouldn't hold up this PR. Re-running testing and switching to "accept", sorry.

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@swift-ci please test Windows

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@swift-ci please test

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MaxDesiatov commented May 24, 2022 •
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swifterror argument for call has mismatched parameter
%swift.error** %6
  call swiftcc void @swift_willThrow(i8* swiftself undef, %swift.error** noalias nocapture readonly dereferenceable(4) %6) #5
in function $sSYsSeRzSb8RawValueSYRtzrlE4fromxs7Decoder_p_tKcfC

this macOS failure is related I guess?

@kateinoigakukun have you seen this error before?

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Hmm weird. I perhaps missed somewhere that calls the function. Let me investigate

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@swift-ci please test

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@swift-ci please test

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kateinoigakukun commented May 28, 2022 •
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OK, I forgot that swifterror is not supported on x86. I've fixed it and CI is now green ✅

@kateinoigakukun kateinoigakukun merged commit e9fb909 into main May 28, 2022
@kateinoigakukun kateinoigakukun deleted the maxd/wasm-swifterror branch May 28, 2022 14:11
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@MaxDesiatov @kateinoigakukun @DougGregor