Hi,
Gentle ping https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596212.html
BR,
Kewen
on 2022/6/6 14:20, Kewen.Lin via Gcc-patches wrote:
> Hi,
>
> PR105459 exposes one issue in inline_call handling that when it
> decides to copy FP flags from callee to caller and rebuild the
> optimization node for caller fndecl, it's possible that the target
> option node is also necessary to be rebuilt. Without updating
> target option node early, it can make nodes share the same target
> option node wrongly, later when we want to unshare it somewhere
> (like in target hook) it can get unexpected results, like ICE on
> uninitialized secondary member of target globals exposed in this PR.
>
> Commit r12-3721 makes it get exact fp_expression info and causes
> more optimization chances then exposes this issue. Commit r11-5855
> introduces two target options to shadow flag_excess_precision and
> flag_unsafe_math_optimizations and shows the need to rebuild target
> node in inline_call when optimization node changes.
>
> As commented in PR105459, I tried to postpone init_function_start
> in cgraph_node::expand, but abandoned it since I thought it just
> concealed the issue. And I also tried to adjust the target node
> when current function switching, but failed since we get the NULL
> cfun and fndecl in WPA phase.
>
> Bootstrapped and regtested on x86_64-redhat-linux, powerpc64-linux-gnu
> P8 and powerpc64le-linux-gnu P9.
>
> Any thoughts? Is it OK for trunk?
>
> BR,
> Kewen
> -----
>
> PR tree-optimization/105459
>
> gcc/ChangeLog:
>
> * ipa-inline-transform.cc (inline_call): Rebuild target option node
> once optimization node gets rebuilt.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/lto/pr105459_0.c: New test.
> ---
> gcc/ipa-inline-transform.cc | 50 +++++++++++++++++++++++++--
> gcc/testsuite/gcc.dg/lto/pr105459_0.c | 35 +++++++++++++++++++
> 2 files changed, 83 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/lto/pr105459_0.c
>
> diff --git a/gcc/ipa-inline-transform.cc b/gcc/ipa-inline-transform.cc
> index 07288e57c73..edba58377f4 100644
> --- a/gcc/ipa-inline-transform.cc
> +++ b/gcc/ipa-inline-transform.cc
> @@ -52,6 +52,7 @@ along with GCC; see the file COPYING3. If not see
> #include "ipa-modref.h"
> #include "symtab-thunks.h"
> #include "symtab-clones.h"
> +#include "target.h"
>
> int ncalls_inlined;
> int nfunctions_inlined;
> @@ -469,8 +470,53 @@ inline_call (struct cgraph_edge *e, bool update_original,
> }
>
> /* Reload global optimization flags. */
> - if (reload_optimization_node && DECL_STRUCT_FUNCTION (to->decl) == cfun)
> - set_cfun (cfun, true);
> + if (reload_optimization_node)
> + {
> + /* Only need to check and update target option node
> + when target_option_default_node is not NULL. */
> + if (target_option_default_node)
> + {
> + /* Save the current context for optimization and target option
> + node. */
> + tree old_optimize
> + = build_optimization_node (&global_options, &global_options_set);
> + tree old_target_opt
> + = build_target_option_node (&global_options, &global_options_set);
> +
> + /* Restore optimization with new optimizatin node. */
> + tree new_optimize = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (to->decl);
> + if (old_optimize != new_optimize)
> + cl_optimization_restore (&global_options, &global_options_set,
> + TREE_OPTIMIZATION (new_optimize));
> +
> + /* Restore target option with the one from caller fndecl. */
> + tree cur_target_opt = DECL_FUNCTION_SPECIFIC_TARGET (to->decl);
> + if (!cur_target_opt)
> + cur_target_opt = target_option_default_node;
> + cl_target_option_restore (&global_options, &global_options_set,
> + TREE_TARGET_OPTION (cur_target_opt));
> +
> + /* Update target option as optimization changes. */
> + targetm.target_option.override ();
> +
> + /* Rebuild target option node for caller fndecl and replace
> + with it if the node changes. */
> + tree new_target_opt
> + = build_target_option_node (&global_options, &global_options_set);
> + if (cur_target_opt != new_target_opt)
> + DECL_FUNCTION_SPECIFIC_TARGET (to->decl) = new_target_opt;
> +
> + /* Restore the context with previous saved nodes. */
> + if (old_optimize != new_optimize)
> + cl_optimization_restore (&global_options, &global_options_set,
> + TREE_OPTIMIZATION (old_optimize));
> + cl_target_option_restore (&global_options, &global_options_set,
> + TREE_TARGET_OPTION (old_target_opt));
> + }
> +
> + if (DECL_STRUCT_FUNCTION (to->decl) == cfun)
> + set_cfun (cfun, true);
> + }
>
> /* If aliases are involved, redirect edge to the actual destination and
> possibly remove the aliases. */
> diff --git a/gcc/testsuite/gcc.dg/lto/pr105459_0.c
> b/gcc/testsuite/gcc.dg/lto/pr105459_0.c
> new file mode 100644
> index 00000000000..c799e6ef23d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/lto/pr105459_0.c
> @@ -0,0 +1,35 @@
> +/* { dg-lto-do link } */
> +/* { dg-lto-options { { -flto -O1 } } } */
> +
> +double m;
> +int n;
> +
> +__attribute__ ((optimize ("-funsafe-math-optimizations")))
> +void
> +bar (int x)
> +{
> + n = x;
> + m = n;
> +}
> +
> +__attribute__ ((flatten))
> +void
> +foo (int x)
> +{
> + bar (x);
> +}
> +
> +void
> +quux (void)
> +{
> + ++n;
> +}
> +
> +int
> +main (void)
> +{
> + foo (0);
> + quux ();
> +
> + return 0;
> +}
> --
> 2.27.0
