mconst 3fb8c5b431 [X86] Fix invalid instructions on x32 with large stack frames (#124041) ...

`X86FrameLowering::emitSPUpdate()` assumes that 64-bit targets use a
64-bit stack pointer, but that's not true on x32.
When checking the stack pointer size, we need to look at
`Uses64BitFramePtr` rather than `Is64Bit`. This avoids generating
invalid instructions like `add esp, rcx`.

For impossibly-large stack frames (4 GiB or larger with a 32-bit stack
pointer), we were also generating invalid instructions like `mov eax,
5000000000`. The inline stack probe code already had a check for that
situation; I've moved the check into `emitSPUpdate()`, so any attempt to
allocate a 4 GiB stack frame with a 32-bit stack pointer will now trap
rather than adjusting ESP by the wrong amount. This also fixes the
"can't have 32-bit 16GB stack frame" assertion, which used to be
triggerable by user code but is now correct.

To help catch situations like this in the future, I've added
`-verify-machineinstrs` to the stack clash tests that generate large
stack frames.

This fixes the expensive-checks buildbot failure caused by #113219.

2025-01-23 12:37:07 +05:30

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