[PATCH] XCOFF select section tweak

[Richard Henderson]

On Wed, Sep 11, 2002 at 01:42:45PM -0400, David Edelsohn wrote:
> !   unsigned int align;
> !   unsigned int flags = default_section_type_flags_1 (decl, name, reloc, 1);
> ! 
> !   /* Align to at least UNIT size.  */
> !   if (flags & SECTION_CODE)
> !     align = MIN_UNITS_PER_WORD;
> !   else
> !     /* Increase alignment of large objects if not already stricter.  */
> !     align = MAX ((DECL_ALIGN (decl) / BITS_PER_UNIT),
> ! 		 int_size_in_bytes (TREE_TYPE (decl)) > MIN_UNITS_PER_WORD
> ! 		 ? UNITS_PER_FP_WORD : MIN_UNITS_PER_WORD);
> ! 
> !   return flags | (exact_log2 (align) & SECTION_ENTSIZE);

This won't work.

You'll generate an error for

	double d __attribute__((section("foo"));
	char c __attribute__((section("foo"));

because the alignment of the two decls is different, which will
result in two different flags settings, which will fail the 
check in set_named_section_flags.

Currently there is no way to know beforehand what the maximum
alignment for a section will be.  If you absolutely positively
need to know this the first time you enter a section, you'll
have to emit assembly in multiple parts.  See iris6_asm_file_end
for the bletcherous details of this scheme.


r~