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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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