Re: [PATCH v2] rs6000: Add 2 built-ins to read the Time Base Register on PowerPC

["Tulio Magno Quites Machado Filho" <tuliom at linux dot vnet dot ibm dot com>]

Segher Boessenkool <segher@kernel.crashing.org> writes:

> > > I don't think TARGET_MFCRF is correct.  For example, if you 
> > > use
> > > -mcpu=powerpc64 (which doesn't set this flag) you will get 
> > > code
> > > that does not run on the newer machines.
> >
> > Sorry, but it seems to be working here...
> > I explain how I tested this in the end of the email.
>
> David tells me all current CPUs actually do support the MFTB 
> insns
> just fine, so that there is no problem.

I don't understand the problem.

Let me paste again this snippet of code here:
It was generated using the __builtin_ppc_get_timebase test case 
with the
extra parameters -S -m64 -mcpu=power7. The rest is the same used 
by the
test suite.

.L.main:
	std 31,-8(1)
	stdu 1,-80(1)
	mr 31,1
	mfspr 9, 268
	std 9,56(31)
	li 9,0
	stw 9,48(31)
	b .L2

I've just done this same test for all -mcpu values from power3 
through power7
and both -m32 and -m64. The only value that outputs mftb is power3 
in both
environments.

What am I missing?

--
Tulio Magno