Re: [RFC][PATCH 21/22] Add Makerules to build %.o and %.os from %.i8

[Joseph Myers <joseph at codesourcery dot com>]

On Tue, 20 Oct 2015, Gary Benson wrote:

> This commit adds make rules to build %.o and %.os files from %.i8
> Infinity note source code.
> 
> In order to ensure the correct preprocessor and assembler are used
> for cross-builds the compilation is done in three stages.  The target
> preprocessor specified at ./configure time is used to preprocess the
> %.i8 source; I8C consumes this preprocessed source and emits assembly
> language; and finally the target assembler specified at ./configure
> time is used to assemble the generated assembly language into object
> code.
> 
> I don't *think* the %.o and %.os files should differ (they don't
> contain "real" code, just PT_NOTE sections) but please tell me if
> I'm wrong and I will add a separate %.S -> %.os rule.

On some platforms the options passed to GCC when compiling a .S file 
affect the options passed to the assembler, which in turn affects the ELF 
header (this applies e.g. to MIPS passing -KPIC).  So I think you do need 
to compile the files separately.

On some platforms, even assembler files with no actual code need to 
contain certain assembler directives to be ABI-compatible with those 
generated by the compiler.  In particular, this applies to ARM; see the 
.eabi_attribute directives in sysdeps/arm/sysdep.h.  If generating a .S 
file, you should make sure it includes <sysdep.h> so that such directives 
are present.

-- 
Joseph S. Myers
joseph@codesourcery.com