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SubjectRe: [patch 02/2] allow gcc4 to optimize unit-at-a-time
On Wed, Dec 28, 2005 at 01:28:15PM +0100, Sam Ravnborg wrote:
> On Wed, Dec 28, 2005 at 07:04:35AM -0500, Jakub Jelinek wrote:
> > > +# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use
> > > +# a lot more stack due to the lack of sharing of stacklots:
> > > +CFLAGS += $(shell if [ $(GCC_VERSION) -lt 0400 ] ; then echo "-fno-unit-at-a-time"; fi ;)
> >
> > -fno-unit-at-a-time option has been introduced in GCC 3.4 (and 3.3-hammer
> > branch). So unless the minimum supported GCC version to compile kernel is
> > 3.4+, you need to replace
> > echo "-fno-unit-at-a-time"
> > with
> > $(call cc-option,-fno-unit-at-a-time)
> The test "$(GCC_VERSION) -lt 0400" takes care of this.

No.
-fno-unit-at-a-time should be used with GCCs that
a) support it
b) are older than GCC 4.0

The "$(GCC_VERSION) -lt 0400" test cares of b),
$(call cc-option,-fno-unit-at-a-time) cares of a).

Jakub
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