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Re: i386 target-help bug?


On Wed, 6 Apr 2011, Paul Koning wrote:

> On Apr 6, 2011, at 4:56 PM, Joseph S. Myers wrote:
> 
> > On Wed, 6 Apr 2011, Paul Koning wrote:
> > 
> >> In i386-gcc 4.5.1, --target-help says that "generic32" and "generic64" 
> >> are valid values for -march= and -mtune.  In fact, those values are 
> >> rejected (even though there seems to be code in i386.c to handle those 
> >> values).
> > 
> > See PR 45731.  This is help for assembler options, not compiler options.
> 
> But mtune= is a compiler switch, so why would --target-help describe 
> "generic64" as a valid choice for that switch when it is not?

Because it is a valid choice for the assembler switch of the same name as 
the compiler switch.  Look at the correct output from a trunk compiler:

The following options are target specific:
[...]
  -mtune=                     Schedule code for given CPU
[...]

Assembler options
=================

Use "-Wa,OPTION" to pass "OPTION" to the assembler.

[...]
  -mtune=CPU              optimize for CPU, CPU is one of:
                           i8086, i186, i286, i386, i486, pentium, pentiumpro,
                           pentiumii, pentiumiii, pentium4, prescott, nocona,
                           core, core2, k6, k6_2, athlon, k8, amdfam10,
                           generic32, generic64
[...]

Using -Wa,-mtune=generic64 works fine.

-- 
Joseph S. Myers
joseph@codesourcery.com


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