[all-commits] [llvm/llvm-project] 55611d: [X86] Fix musttail miscompilation when arguments a...

[Mariusz Masztalerczuk via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 55611ddbaec24686d5702255fbd6033b38dd9ea4
      https://github.com/llvm/llvm-project/commit/55611ddbaec24686d5702255fbd6033b38dd9ea4
  Author: Mariusz Masztalerczuk <mariusz at masztalerczuk.com>
  Date:   2026-06-10 (Wed, 10 Jun 2026)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLoweringCall.cpp
    M llvm/test/CodeGen/X86/hipe-cc64.ll
    M llvm/test/CodeGen/X86/musttail-tailcc.ll
    M llvm/test/CodeGen/X86/sibcall.ll
    M llvm/test/CodeGen/X86/swifttailcc-store-ret-address-aliasing-stack-slot.ll

  Log Message:
  -----------
  [X86] Fix musttail miscompilation when arguments are passed on the stack (#199691)

After commit 782bf6a, a musttail call with matching CC was always
treated as a sibcall, which skips the stores of outgoing stack
arguments. Any non-forwarded stack argument was silently dropped.

Only treat musttail as a sibcall when every argument is in a register;
otherwise fall back to full tail-call lowering.

Fix #199224

---------

Co-authored-by: Reid Kleckner <rkleckner at nvidia.com>



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