[all-commits] [llvm/llvm-project] 3fb8c5: [X86] Fix invalid instructions on x32 with large s...

[mconst via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3fb8c5b43195d6e11ff0557d07e75700343d369f
      https://github.com/llvm/llvm-project/commit/3fb8c5b43195d6e11ff0557d07e75700343d369f
  Author: mconst <mconst at gmail.com>
  Date:   2025-01-23 (Thu, 23 Jan 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86FrameLowering.cpp
    M llvm/test/CodeGen/X86/stack-clash-extra-huge.ll
    M llvm/test/CodeGen/X86/stack-clash-huge.ll

  Log Message:
  -----------
  [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.



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