Stream: git-wasmtime

Topic: wasmtime / Issue #1498 Cranelift: clean up generated call...

Wasmtime GitHub notifications bot (Apr 10 2020 at 20:55):

iximeow opened Issue #1498:

In isa/x86/abi.rs we have to save callee-preserved FPRs for some calling conventions. We save these to the stack and reload them before exiting, but at the moment the Cranelift IR operations stack_load and stack_store are not directly encodable. In other parts of a function, stack_load and stack_store would be legalized and then optimized into the assembly we'd like (movdqa [rsp + offset], xmm*), but prologue/epilogue addition happen after both legalization and register allocation.

When stack_load and stack_store can be directly encoded, we can switch to those, remove an explicit stack_address, and simplify x86 callee-preserved FPR machinery.

For more, see this comment and this comment.

Wasmtime GitHub notifications bot (Apr 10 2020 at 20:55):

iximeow labeled Issue #1498:

In isa/x86/abi.rs we have to save callee-preserved FPRs for some calling conventions. We save these to the stack and reload them before exiting, but at the moment the Cranelift IR operations stack_load and stack_store are not directly encodable. In other parts of a function, stack_load and stack_store would be legalized and then optimized into the assembly we'd like (movdqa [rsp + offset], xmm*), but prologue/epilogue addition happen after both legalization and register allocation.

When stack_load and stack_store can be directly encoded, we can switch to those, remove an explicit stack_address, and simplify x86 callee-preserved FPR machinery.

For more, see this comment and this comment.

Wasmtime GitHub notifications bot (Apr 10 2020 at 20:56):

github-actions[bot] commented on Issue #1498:

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Wasmtime GitHub notifications bot (Apr 10 2020 at 20:56):

iximeow edited Issue #1498:

In isa/x86/abi.rs we have to save callee-preserved FPRs for some calling conventions. We save these to the stack and reload them before exiting, but at the moment the Cranelift IR operations stack_load and stack_store are not directly encodable. In other parts of a function, stack_load and stack_store would be legalized and then optimized into the assembly we'd like (movdqa [rsp + offset], xmm*), but prologue/epilogue addition happen after both legalization and register allocation.

When stack_load and stack_store can be directly encoded, we can switch to those, remove an explicit stack_address, and simplify x86 callee-preserved FPR machinery. #1198 adds these encodings.

For more, see this comment and this comment.

Wasmtime GitHub notifications bot (Feb 03 2021 at 18:25):

bjorn3 commented on Issue #1498:

I think this is fixed with the new backend framework.

Wasmtime GitHub notifications bot (Feb 03 2021 at 19:18):

cfallin closed Issue #1498:

In isa/x86/abi.rs we have to save callee-preserved FPRs for some calling conventions. We save these to the stack and reload them before exiting, but at the moment the Cranelift IR operations stack_load and stack_store are not directly encodable. In other parts of a function, stack_load and stack_store would be legalized and then optimized into the assembly we'd like (movdqa [rsp + offset], xmm*), but prologue/epilogue addition happen after both legalization and register allocation.

When stack_load and stack_store can be directly encoded, we can switch to those, remove an explicit stack_address, and simplify x86 callee-preserved FPR machinery. #1198 adds these encodings.

For more, see this comment and this comment.

Last updated: Dec 13 2025 at 19:03 UTC