On October 21, 2018 10:06:06 AM GMT+02:00, Alexandre Oliva <aol...@redhat.com>
wrote:
>The isolate-paths pass is activated by various -f flags, but also by
>-Wnull-dereference. Most of its codegen changes are conditioned on at
>least one of the -f flags, but those that detect, warn about and
>isolate paths that return the address of local variables are enabled
>even if the pass is activated only by -Wnull-dereference.
>
>-W flags should not cause codegen changes, so this patch makes the
>codegen changes conditional on the presence of any of the -f flags
>that activate the pass. Should we have a separate option to activate
>only this kind of transformation?
I don't think this is necessary.
>Regstrapped on x86_64- and i686-linux-gnu. Ok to install?
OK.
Richard.
>
>for gcc/ChangeLog
>
> * gimple-ssa-isolate-paths.c
> (find_implicit_erroneous_behavior): Do not change code if the
> pass is running for warnings only.
> (find_explicit_erroneous_behavior): Likewise.
>---
> gcc/gimple-ssa-isolate-paths.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
>diff --git a/gcc/gimple-ssa-isolate-paths.c
>b/gcc/gimple-ssa-isolate-paths.c
>index e1fab61bedab..880836c21aa7 100644
>--- a/gcc/gimple-ssa-isolate-paths.c
>+++ b/gcc/gimple-ssa-isolate-paths.c
>@@ -431,7 +431,9 @@ find_implicit_erroneous_behavior (void)
> "declared here");
> }
>
>- if (gimple_bb (use_stmt) == bb)
>+ if ((flag_isolate_erroneous_paths_dereference
>+ || flag_isolate_erroneous_paths_attribute)
>+ && gimple_bb (use_stmt) == bb)
> {
> duplicate = isolate_path (bb, duplicate, e,
> use_stmt, lhs, true);
>@@ -553,9 +555,16 @@ find_explicit_erroneous_behavior (void)
> inform (DECL_SOURCE_LOCATION(valbase),
> "declared here");
> }
>- tree zero = build_zero_cst (TREE_TYPE (val));
>- gimple_return_set_retval (return_stmt, zero);
>- update_stmt (stmt);
>+
>+ /* Do not modify code if the user only asked for
>+ warnings. */
>+ if (flag_isolate_erroneous_paths_dereference
>+ || flag_isolate_erroneous_paths_attribute)
>+ {
>+ tree zero = build_zero_cst (TREE_TYPE (val));
>+ gimple_return_set_retval (return_stmt, zero);
>+ update_stmt (stmt);
>+ }
> }
> }
> }
