On Wed, May 13, 2026 at 12:00 AM H.J. Lu <[email protected]> wrote:
>
> In 64-bit mode, for preserve_none functions, DRAP may use any register
> except AX, R12–R15, DI, SI (argument registers), SP, and BP. Use R11.
> In non-callee-saved functions, R10 and R13 are also available since they
> are not used for parameter passing. In 32-bit mode, preserve_none does
> not affect parameter passing, so the current approach remains valid.
>
> DRAP register is used to restore stack pointer in epilogue for stack
> realignment. Always save and restore DRAP register between prologue
> and epilogue so that stack pointer can be restored.
>
> Tested on Linux/x86-64 and with CPython 3.14.4.
>
> gcc/
>
> PR target/120870
> * config/i386/i386.cc (ix86_save_reg): Return true for DRAP
> register early at entry.
> (find_drap_reg): Use R11_REG in preserve_none functions in
> 64-bit mode.
>
> gcc/testsuite/
>
> PR target/120870
> * gcc.target/i386/pr120870-1.c: New test.
> * gcc.target/i386/pr120870-2.c: Likewise.
+
+__attribute__ ((preserve_none)) void
+tail (long a, long b)
+{
+}
This function doesn't need to be preserve_none, and the test will
still fail with the unpatched compiler.
OK with the above adjustion.
Thanks,
Uros.
