Re: [RFD] MIPS/gas: Optimisation cannot be set to 0

[Ian Lance Taylor <iant at google dot com>]

"Maciej W. Rozycki" <macro@mips.com> writes:

> Wed Feb 12 14:36:29 1997  Ian Lance Taylor  <ian@cygnus.com>
> 
> 	* config/tc-mips.c (md_parse_option): When debugging, set
> 	mips_optimize to 1, not 0.

My vague recollection of the problem is that at least at that time gcc
would always pass a -O option to the assembler.  When not optimizing,
it would pass -O0.  However, inserting NOPs for MIPS variants which do
not need them does not help debugging.

Clearly failing to provide a way to set mips_optimize to 0 was an
oversight.

>  I have no strong preference, but I think gas should have a mode where its 
> input is assembled intact.  And swapping branches may produce surprising 
> interactions with debugging information.  I am therefore in favour to the 
> first proposal above, but I would like to hear from the others.

I'm not sure I see the relevance of "assembled intact."  The source is
assembled just as the user specified with -O1.  -O1 simply inhibits
adding additional unnecessary nop instructions--nop instructions that
were required for MIPS ISA I but not for later ISAs.

At -O1 branches are not swapped, so debugging is not impaired.

I agree there should be a way to set mips_optimize to 0, but we should
ensure that gcc -O0 does not set mips_optimize to 0 when assembling.

Ian