Hello, This is my proposed fix for PR53948. We don't want to put user variables in callee-clobbered registers, but obviously function arguments are OK there. REG_USERVAR_P is set on PARM_DECLs and on user variables, so it can't be used to distinguish between the two.
As it turns out, I can hi-jack a bit for that: 'unchanging' (currently
incorrectly documented as used on REG) for a new macro
REG_FUNCTION_PARM_P. I found one obvious place where this bit can be
used instead of REG_USERVAR_P, and probably there are a few more
places where this is useful (TBD, I'm going to look at all places
where RTL code looks at tree's PARM_DECL later).
Bootstrapped&tested on powerpc64-unknown-linux-gnu.
OK for trunk?
Ciao!
Steven
PR debug/53948
* rtl.h (REG_FUNCTION_PARM_P): New flag on a REG. Re-use 'unchaning'.
* emit-rtl.c (mark_function_parm_reg): New function.
* function.c (assign_parm_setup_reg): Use mark_function_parm_reg
instead of mark_user_reg.
* combine.c (can_change_dest_mode): Preserve REG_FUNCTION_PARM_P.
* web.c (entry_register): Likewise.
* reload1.c (reload): Likewise.
* ira-emit.c (ira_create_new_reg): Likewise.
* reginfo.c (reg_scan_mark_refs): Likewise.
* optabs.c (emit_libcall_block_1): Use REG_FUNCTION_PARM_P instead
of REG_USERVAR_P.
* regstat.c (dump_reg_info): Print REG_FUNCTION_PARM_P.
* doc/rtl.texi (REG_FUNCTION_PARM_P): Document it.
('unchanging' flag): Fix documentation.
PR53948.diff
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