Skip to content

[wasm R2R] Align 8-byte stack locals and keep frames 16-aligned #129815

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
AndyAyersMS merged 1 commit into from
Jun 25, 2026
Merged

[wasm R2R] Align 8-byte stack locals and keep frames 16-aligned #129815

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 15 additions & 4 deletions src/coreclr/jit/lclvars.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5753,7 +5753,9 @@ int Compiler::lvaAllocLocalAndSetVirtualOffset(unsigned lclNum, unsigned size, i
noway_assert(lclNum != BAD_VAR_NUM);

LclVarDsc* lcl = lvaGetDesc(lclNum);
#ifdef TARGET_64BIT
#if defined(TARGET_64BIT) || defined(TARGET_WASM)
// Align >=8 byte locals to 8 bytes.
//
// Before final frame layout, assume the worst case, that every >=8 byte local will need
// maximum padding to be aligned. This is because we generate code based on the stack offset
// computed during tentative frame layout. These offsets cannot get bigger during final
Expand Down Expand Up @@ -5825,7 +5827,7 @@ int Compiler::lvaAllocLocalAndSetVirtualOffset(unsigned lclNum, unsigned size, i
}
#endif
}
#endif // TARGET_64BIT
#endif // TARGET_64BIT || TARGET_WASM

/* Reserve space on the stack by bumping the frame size */

Expand Down Expand Up @@ -6046,8 +6048,17 @@ void Compiler::lvaAlignFrame()
}
}
#elif defined(TARGET_WASM)
// TODO-WASM: decide what the stack alignment strategy should be. In the native ABI, the alignment is 16, but that
// may be suboptimal for the managed ABI, since it may imply zeroing the padding slots.
// Keep the stack aligned to STACK_ALIGN.
if ((compLclFrameSize % STACK_ALIGN) != 0)
{
lvaIncrementFrameSize(STACK_ALIGN - (compLclFrameSize % STACK_ALIGN));
}
else if (lvaDoneFrameLayout != FINAL_FRAME_LAYOUT)
{
// Reserve a full STACK_ALIGN so the offsets computed now are upper bounds.
lvaIncrementFrameSize(STACK_ALIGN);
}
assert((compLclFrameSize % STACK_ALIGN) == 0);
#else
NYI("TARGET specific lvaAlignFrame");
#endif
Expand Down
Loading