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    SubjectRe: [2.6 patch] blackfin: "extern inline" -> "static inline"
    On Thu, Oct 25, 2007 at 04:20:20PM -0400, Mike Frysinger wrote:
    > On 10/25/07, Adrian Bunk <bunk@kernel.org> wrote:
    > > On Thu, Oct 25, 2007 at 04:07:45PM -0400, Mike Frysinger wrote:
    > > > On 10/25/07, Adrian Bunk <bunk@kernel.org> wrote:
    > > > > On Thu, Oct 25, 2007 at 12:16:40PM -0400, Mike Frysinger wrote:
    > > > > > On 10/25/07, Adrian Bunk <bunk@kernel.org> wrote:
    > > > > > > On Wed, Oct 24, 2007 at 08:06:14PM -0700, H. Peter Anvin wrote:
    > > > > > > > Mike Frysinger wrote:
    > > > > > > >> we'll have to either use the gcc attributes to force old inline
    > > > > > > >> behavior or use the gcc flag to force it
    > > > > > > >
    > > > > > > > We should probably have an extern_inline define then, assuming this is a
    > > > > > > > function that does exist in a linkable version already -- otherwise "static
    > > > > > > > inline" is correct.
    > > > > > >
    > > > > > > Since we #define inline to be __attribute__((always_inline))
    > > > > > > "extern inline" with the old semantics would only behave differently
    > > > > > > if someone took the address of one of these string functions.
    > > > > >
    > > > > > that isnt what we intended ;)
    > > > > >
    > > > > > > Does this happen anywhere in the blackfin port?
    > > > > >
    > > > > > gcc is also free to ignore the optimized inline in favor of an
    > > > > > external reference
    > > > >
    > > > > It is not since we #define inline to be __attribute__((always_inline)).
    > > >
    > > > as i said, that was not what we intended ... and actually,
    > > > always_inline does not mean always inline ... it is still possible to
    > > > get gcc to not inline things when building debug versions.
    > >
    > > Do you have any example for your claim "to get gcc to not inline things
    > > when building debug versions"?
    >
    > $ cat test.c
    > __attribute__((always_inline)) int foo(void) { return 0; }
    > int main(void){ return foo(); }
    > $ gcc -g test.c -o test
    > $ readelf -s test | grep FUNC | grep -v _
    > 61: 00000000004004b8 11 FUNC GLOBAL DEFAULT 13 foo
    > 68: 00000000004004c3 11 FUNC GLOBAL DEFAULT 13 main
    >
    > looks pretty straightforward to me

    That a function gets emitted for a non-static inline function is
    expected (and unrelated to the static inline cases).

    But if you replace "__attribute__((always_inline))" with
    "inline __attribute__((always_inline))" as we do in the kernel,
    foo() is no longer called from main().

    And if you make it "static inline __attribute__((always_inline))" (which
    is what "static inline" in the kernel expands to), there's no longer a
    function "foo" in the binary.

    > -mike

    cu
    Adrian

    --

    "Is there not promise of rain?" Ling Tan asked suddenly out
    of the darkness. There had been need of rain for many days.
    "Only a promise," Lao Er said.
    Pearl S. Buck - Dragon Seed

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