On Fri, Jan 16, 2015 at 04:04:27PM +0100, Martin Liška wrote:
> Hello.
>
> This patch adds support for __attribute__((no_icf)) that prevents a function
> being merged with a different one.
>
> Tested on x86_64-linux-pc.
>
> Ready for trunk?
> Thanks,
> Martin
> From 234fc8018f9810e2adf6d975d6d0051631ef8c02 Mon Sep 17 00:00:00 2001
> From: mliska <mli...@suse.cz>
> Date: Fri, 16 Jan 2015 14:35:23 +0100
> Subject: [PATCH] IPA ICF: add no_icf attribute.
>
> gcc/c-family/ChangeLog:
>
> 2015-01-16 Martin Liska <mli...@suse.cz>
>
> * c-common.c (handle_noicf_attribute): New function.
>
> gcc/ChangeLog:
>
> 2015-01-16 Martin Liska <mli...@suse.cz>
>
> * doc/extend.texi (no_icf): Add new attribute description.
> * ipa-icf.c (sem_item_optimizer::merge_classes): Handle cases
> where the pass attempts to merge a function with no_icf attribute.
>
> gcc/testsuite/ChangeLog:
>
> 2015-01-16 Martin Liska <mli...@suse.cz>
>
> * gcc.dg/ipa/ipa-icf-33.c: New test.
> ---
> gcc/c-family/c-common.c | 21 +++++++++++++++++++++
> gcc/doc/extend.texi | 6 ++++++
> gcc/ipa-icf.c | 8 ++++++++
> gcc/testsuite/gcc.dg/ipa/ipa-icf-33.c | 27 +++++++++++++++++++++++++++
> 4 files changed, 62 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/ipa/ipa-icf-33.c
>
> diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
> index eb132c5..3c18d1c 100644
> --- a/gcc/c-family/c-common.c
> +++ b/gcc/c-family/c-common.c
> @@ -330,6 +330,7 @@ static tree handle_no_sanitize_undefined_attribute (tree
> *, tree, tree, int,
> static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
> static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
> static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
> +static tree handle_noicf_attribute (tree *, tree, tree, int, bool *);
> static tree handle_leaf_attribute (tree *, tree, tree, int, bool *);
> static tree handle_always_inline_attribute (tree *, tree, tree, int,
> bool *);
> @@ -664,6 +665,8 @@ const struct attribute_spec c_common_attribute_table[] =
> handle_noinline_attribute, false },
> { "noclone", 0, 0, true, false, false,
> handle_noclone_attribute, false },
> + { "no_icf", 0, 0, true, false, false,
> + handle_noicf_attribute, false },
> { "leaf", 0, 0, true, false, false,
> handle_leaf_attribute, false },
> { "always_inline", 0, 0, true, false, false,
> @@ -6853,6 +6856,24 @@ handle_noclone_attribute (tree *node, tree name,
> return NULL_TREE;
> }
>
> +/* Handle a "no_icf" attribute; arguments as in
> + struct attribute_spec.handler. */
> +
> +static tree
> +handle_noicf_attribute (tree *node, tree name,
> + tree ARG_UNUSED (args),
> + int ARG_UNUSED (flags), bool *no_add_attrs)
> +{
> + if (TREE_CODE (*node) != FUNCTION_DECL)
> + {
> + warning (OPT_Wattributes, "%qE attribute ignored", name);
> + *no_add_attrs = true;
> + }
> +
> + return NULL_TREE;
> +}
> +
> +
> /* Handle a "always_inline" attribute; arguments as in
> struct attribute_spec.handler. */
>
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index bf6d710..ba921e9 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -2195,6 +2195,7 @@ attribute specification inside double parentheses. The
> following
> attributes are currently defined for functions on all targets:
> @code{aligned}, @code{alloc_size}, @code{alloc_align}, @code{assume_aligned},
> @code{noreturn}, @code{returns_twice}, @code{noinline}, @code{noclone},
> +@code{no_icf},
> @code{always_inline}, @code{flatten}, @code{pure}, @code{const},
> @code{nothrow}, @code{sentinel}, @code{format}, @code{format_arg},
> @code{no_instrument_function}, @code{no_split_stack},
> @@ -3475,6 +3476,11 @@ cloning---a mechanism that produces specialized copies
> of functions
> and which is (currently) performed by interprocedural constant
> propagation.
>
> +@item no_icf
> +@cindex @code{no_icf} function attribute
> +This function attribute prevents a functions from being merged with another
s/functions/function/
> +semantically equivalent function.
> +
> @item nonnull (@var{arg-index}, @dots{})
> @cindex @code{nonnull} function attribute
> The @code{nonnull} attribute specifies that some function parameters should
> diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
> index bbd5724..4b70900 100644
> --- a/gcc/ipa-icf.c
> +++ b/gcc/ipa-icf.c
> @@ -2372,6 +2372,14 @@ sem_item_optimizer::merge_classes (unsigned int
> prev_class_count)
> source->asm_name (), alias->asm_name ());
> }
>
> + if (lookup_attribute ("no_icf", DECL_ATTRIBUTES (alias->decl)))
> + {
> + if (dump_file)
> + fprintf (dump_file, "Merge operation is skipped due to no_icf
> attribute.\n\n");
Note that this line is too long.
> + continue;
> + }
> +
> if (dump_file && (dump_flags & TDF_DETAILS))
> {
> source->dump_to_file (dump_file);
> diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-icf-33.c
> b/gcc/testsuite/gcc.dg/ipa/ipa-icf-33.c
> new file mode 100644
> index 0000000..d7e814d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/ipa/ipa-icf-33.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O0 -fipa-icf -fdump-ipa-icf" } */
> +
> +#include <stdio.h>
> +
> +static int
> +__attribute__ ((no_icf))
> +foo()
> +{
> + return 2;
> +}
> +
> +static int
> +__attribute__ ((no_icf))
> +bar()
> +{
> + return 2;
> +}
> +
> +int main()
> +{
> + return foo() - bar();
> +}
> +
> +/* { dg-final { scan-ipa-dump "Equal symbols: 1" "icf" } } */
> +/* { dg-final { scan-ipa-dump "Equal symbols: 1" "icf" } } */
> +/* { dg-final { cleanup-ipa-dump "icf" } } */
> --
> 2.1.2
>
Marek
