[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition - #127543

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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.

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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
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On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)

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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)

@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!

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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.

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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?

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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?

@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.

So it seems we can move to using FP instead and get rid of this passing via structs.

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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.

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we compile with -fno-omit-frame-pointer.

That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.

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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.

However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.

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What is the status here? Did you land the change mentioned above @janvorli?

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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.

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I will close this PR once PR #128728 is merged.

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@clamp03 I've just merged my PR in.

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@clamp03 I've just merged my PR in.

Thank you so much!

@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.

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Thank you @clamp03!

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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition - #127543
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
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On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
@clamp03
[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
fbd3628
On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
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On ARM32, bundling arguments in a struct forces register passing, ensuring
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition - #127543
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
@clamp03
[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
fbd3628
On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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, 'i');
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// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition - #127543
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
@clamp03
[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
fbd3628
On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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, 'i');
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
@clamp03
[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
fbd3628
On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
@jakobbotsch
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
@JulieLeeMSFT
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
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Thank you @clamp03!
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition - #127543
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition#127543
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On ARM32, bundling arguments in a struct forces register passing, ensuring the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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[clr-interp] Use struct parameter for InvokeUnmanagedCalliWithTransition
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On ARM32, bundling arguments in a struct forces register passing, ensuring
the SP value saved by SAVE_THE_LOWEST_SP matches what stack walking reports.
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Tagging subscribers to this area: @JulieLeeMSFT, @BrzVlad, @janvorli, @kg

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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
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@clamp03, if you get a chance, could you also run interpreter tests on riscv64? If something fails, please file an issue with build and test commands. I will take from there (I was struggling to figure out commands with --bootstrap earlier but code was ported to riscv64 to the extent that 'it just compiles' 😅)
@am11 Okay, I'll check the interpreter tests on riscv64 after May 5th, as we have a holiday until then. Since I don't have an available riscv64 device now, I'll run the tests using QEMU. Thanks!
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@BrzVlad@davidwrighton@janvorli Could you please review this PR? Thank you.
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@BrzVlad
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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@janvorli
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May 6, 2026

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This seems fragile. Wouldn't it be better to save the FP instead and identify the native frame by this, given this wouldn't change and we wouldn't have to bother with updating every time sp changes ? @janvorli ?
@BrzVlad we did that already for other cases, so this just adds another one. I agree it is ugly. Looking again at where we use the saved SP in the current state, there is one place where we pass it into a call that ends up ignoring it (which wasn't the case when we have decided to use this way of mitigating the SP issue) and then the only remaining one is the ResumeAfterCatch. It seems that one can be modified to use FP as you suggested since we compile with -fno-omit-frame-pointer.
So it seems we can move to using FP instead and get rid of this passing via structs.
@janvorli
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@clamp03 let me try the change that @BrzVlad suggested. If that works, we can close this PR as it would not be needed.
@jkotas
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May 7, 2026

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we compile with -fno-omit-frame-pointer.
That's fragile in a different way. -fno-omit-frame-pointer is not a thing on Windows x64, and the optimizations can setup the FP in non-obvious ways.
@janvorli
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May 7, 2026

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@jkotas on Windows, you are right. We can keep using the SP. On Unix, it seems that it is required for the compiler to not to reuse FP for anything else when -fno-omit-frame-pointer is specified and the function in question is not inlined in some other that is compiled without the -fno-omit-frame-pointer. Both LLVM and GCC marks the frame register register as reserved in such case. Copilot has provided me with links to the source locations in LLVM/GCC and also to related abi docs that seem to confirm that.
However, yesterday I have resumed work on changing the ResumeAfterCatch to get rid of the explicit native frames unwinding and using C++ exception like we do on WASM. That would remove the need for storing the SP or FP completely.
@jakobbotsch
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What is the status here? Did you land the change mentioned above @janvorli?
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@jakobbotsch the change is in PR #128728, I am still fixing some issues with it.
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I will close this PR once PR #128728 is merged.
@JulieLeeMSFT
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June 2, 2026 18:11
@janvorli
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@clamp03 I've just merged my PR in.
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@clamp03 I've just merged my PR in.
Thank you so much!
@janvorli + I will check interpreter on arm32 and then revert all struct parameters in interpexec.
@clamp03clamp03
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Jun 9, 2026
@janvorli
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Thank you @clamp03!
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