VTA merge - cmdline

[Mark Mitchell]

Alexandre Oliva wrote:

>> -fmin-insn-uid should be a --param.

> Where's documentation that explains when a flag should be good old -f
> and when it should be the new (and IMHO redundant) --param?

--param should be used for tuning parameters for the compiler, i.e.,
where we would otherwise be tempted to use "magic constants".  Most
users shouldn't care about them.  In contrast, -f options are ones we
expect users to actually want to use, and we expect numerical parameters
thereto to correspond to something users would understand.

"min-insn-uid" sure doesn't sound like something most users would grok;
it's a purely internal detail of the compiler.  That's in contrast with
something like the maximum number of times to unroll a loop (understood
by a skilled engineer, and observable in the assembly output) or the
maximum number of iterations allowed for some pass (understood at least
at the level of "bigger numbers makes compiler take longer and hopefully
generate better code" and presumably observable in the assembly output).

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713