On 31/03/16 14:11, Ramana Radhakrishnan wrote:
> Hi,
>
> In this PR we have a situation where we aren't really detecting
> weak references vs weak definitions. If one has a weak definition
> that binds locally there's no reason not to put out PC relative
> relocations.
>
> However if you have a genuine weak reference that is
> known not to bind locally it makes very little sense
> to put out an entry into the literal pool which doesn't always
> work with DSOs and shared objects.
>
> Tested aarch64-none-linux-gnu bootstrap and regression test with no
> regressions
>
> This is not a regression and given what we've seen recently with protected
> symbols and binds_locally_p I'd rather this were queued for GCC 7.
>
> Ok ?
>
Yes, this looks fine. Sorry for the delay replying.
R.
> regards
> Ramana
>
> gcc/
>
> * config/aarch64/aarch64.c (aarch64_classify_symbol): Typo in comment fixed.
> Only force to memory if it is a weak external reference.
>
>
> gcc/testsuite
>
> * gcc.target/aarch64/pr63874.c: New test.
>
>
> pr63874.txt
>
>
> commit e41d4bd6abbee99628909d4af612504844dee640
> Author: Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
> Date: Thu Mar 31 13:47:33 2016 +0100
>
> fix PR63874
>
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index cf1239d..6782316 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -9387,15 +9387,18 @@ aarch64_classify_symbol (rtx x, rtx offset)
> switch (aarch64_cmodel)
> {
> case AARCH64_CMODEL_TINY:
> - /* When we retreive symbol + offset address, we have to make sure
> + /* When we retrieve symbol + offset address, we have to make sure
> the offset does not cause overflow of the final address. But
> we have no way of knowing the address of symbol at compile time
> so we can't accurately say if the distance between the PC and
> symbol + offset is outside the addressible range of +/-1M in the
> TINY code model. So we rely on images not being greater than
> 1M and cap the offset at 1M and anything beyond 1M will have to
> - be loaded using an alternative mechanism. */
> - if (SYMBOL_REF_WEAK (x)
> + be loaded using an alternative mechanism. Furthermore if the
> + symbol is a weak reference to something that isn't known to
> + resolve to a symbol in this module, then force to memory. */
> + if ((SYMBOL_REF_WEAK (x)
> + && !aarch64_symbol_binds_local_p (x))
> || INTVAL (offset) < -1048575 || INTVAL (offset) > 1048575)
> return SYMBOL_FORCE_TO_MEM;
> return SYMBOL_TINY_ABSOLUTE;
> @@ -9403,7 +9406,8 @@ aarch64_classify_symbol (rtx x, rtx offset)
> case AARCH64_CMODEL_SMALL:
> /* Same reasoning as the tiny code model, but the offset cap here is
> 4G. */
> - if (SYMBOL_REF_WEAK (x)
> + if ((SYMBOL_REF_WEAK (x)
> + && !aarch64_symbol_binds_local_p (x))
> || !IN_RANGE (INTVAL (offset), HOST_WIDE_INT_C (-4294967263),
> HOST_WIDE_INT_C (4294967264)))
> return SYMBOL_FORCE_TO_MEM;
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr63874.c
> b/gcc/testsuite/gcc.target/aarch64/pr63874.c
> new file mode 100644
> index 0000000..1a745a0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr63874.c
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +/* { dg-skip-if "Not applicable for mcmodel=large" { aarch64*-*-* } {
> "-mcmodel=large" } { "" } } */
> +
> +extern void __attribute__((weak)) foo_weakref (void);
> +void __attribute__((weak, noinline)) bar (void)
> +{
> + return;
> +}
> +void (*f) (void);
> +void (*g) (void);
> +
> +int
> +main (void)
> +{
> + f = &foo_weakref;
> + g = &bar;
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "adr*foo_weakref" } } */
> +/* { dg-final { scan-assembler-not "\\.(word|xword)\tbar" } } */
>
