Re: port-macppc/54827: alloca() is broken in gcc 8 on powerpc

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

The following reply was made to PR port-macppc/54827; it has been noted by GNATS.

From: Valery Ushakov <uwe%stderr.spb.ru@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: matthew green <mrg%eterna.com.au@localhost>
Subject: Re: port-macppc/54827: alloca() is broken in gcc 8 on powerpc
Date: Tue, 21 Jan 2020 17:18:19 +0300

 On Mon, Jan 20, 2020 at 03:30:02 +0000, Valery Ushakov wrote:
 
 > Actually, since we are stomping onto the first local variable I wonder
 > if the one we want is RS6000_STARTING_FRAME_OFFSET that has the
 > (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8 part.
 
 The following diff seems to help though I haven't yet tested variable
 length alloca.  The diff overrides two additional macros that have
 that 16 vs. 8 choice dependent on altivec to always use 16 to match
 our STACK_BOUNDARY.
 
 --- netbsd.h.~1.14.~	2019-10-02 12:53:42.597881037 +0300
 +++ netbsd.h	2020-01-21 16:45:53.231796140 +0300
 @@ -142,6 +142,20 @@
  #undef STACK_BOUNDARY
  #define STACK_BOUNDARY	128
  
 +/* XXX: uwe: override to match STACK_BOUNDARY */
 +#undef RS6000_STARTING_FRAME_OFFSET
 +#define RS6000_STARTING_FRAME_OFFSET					\
 +  (cfun->calls_alloca							\
 +   ? (RS6000_ALIGN (crtl->outgoing_args_size + RS6000_SAVE_AREA, 16))	\
 +   : (RS6000_ALIGN (crtl->outgoing_args_size, 16)			\
 +      + RS6000_SAVE_AREA))
 +
 +/* XXX: uwe: override to match STACK_BOUNDARY */
 +#undef STACK_DYNAMIC_OFFSET
 +#define STACK_DYNAMIC_OFFSET(FUNDECL)					\
 +  RS6000_ALIGN (crtl->outgoing_args_size.to_constant ()			\
 +		+ STACK_POINTER_OFFSET, 16)
 +
  /* Use standard DWARF numbering for DWARF debugging information.  */
  #define RS6000_USE_DWARF_NUMBERING
  
 
 
 -uwe