| Message ID | orv8w4unvg.fsf@lxoliva.fsfla.org |
|---|---|
| State | New |
| Headers | show |
| Series | hardcmp: split before dispatch edge | expand |
On Thu, Mar 24, 2022 at 2:43 AM Alexandre Oliva via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > > If we harden a compare at the end of a block with an edge to the > abnormal dispatch block, it won't have a single successor. Arrange to > split the block at its final stmt so as to have a single succ. > > Regstrapped on x86_64-linux-gnu. Ok to install? OK. > > for gcc/ChangeLog > > PR middle-end/104975 > * gimple-harden-conditionals.cc > (pass_harden_compares::execute): Force split in case of > multiple edges. > > for gcc/testsuite/ChangeLog > > PR middle-end/104975 > * gcc.dg/pr104975.c: New. > --- > gcc/gimple-harden-conditionals.cc | 12 +++++++++--- > gcc/testsuite/gcc.dg/pr104975.c | 20 ++++++++++++++++++++ > 2 files changed, 29 insertions(+), 3 deletions(-) > create mode 100644 gcc/testsuite/gcc.dg/pr104975.c > > diff --git a/gcc/gimple-harden-conditionals.cc b/gcc/gimple-harden-conditionals.cc > index 6a5fc3fb9e1a2..be01f3ea8c44a 100644 > --- a/gcc/gimple-harden-conditionals.cc > +++ b/gcc/gimple-harden-conditionals.cc > @@ -509,10 +509,16 @@ pass_harden_compares::execute (function *fun) > gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT); > > /* We wish to insert a cond_expr after the compare, so arrange > - for it to be at the end of a block if it isn't. */ > - if (!gsi_end_p (gsi_split)) > + for it to be at the end of a block if it isn't, and for it > + to have a single successor in case there's more than > + one, as in PR104975. */ > + if (!gsi_end_p (gsi_split) > + || !single_succ_p (gsi_bb (gsi_split))) > { > - gsi_prev (&gsi_split); > + if (!gsi_end_p (gsi_split)) > + gsi_prev (&gsi_split); > + else > + gsi_split = gsi_last_bb (gsi_bb (gsi_split)); > basic_block obb = gsi_bb (gsi_split); > basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest; > gsi_next (&gsi_split); > diff --git a/gcc/testsuite/gcc.dg/pr104975.c b/gcc/testsuite/gcc.dg/pr104975.c > new file mode 100644 > index 0000000000000..04532fc444340 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/pr104975.c > @@ -0,0 +1,20 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O1 -fharden-compares -fno-inline -fno-ipa-pure-const" } */ > + > +__attribute__ ((pure, returns_twice)) int > +bar (int); > + > +int > +quux (void) > +{ > + return 0; > +} > + > +int > +foo (short int x) > +{ > + x = !x; > + bar (quux ()); > + > + return x; > +} > > > -- > Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ > Free Software Activist GNU Toolchain Engineer > Disinformation flourishes because many people care deeply about injustice > but very few check the facts. Ask me about <https://stallmansupport.org>
diff --git a/gcc/gimple-harden-conditionals.cc b/gcc/gimple-harden-conditionals.cc index 6a5fc3fb9e1a2..be01f3ea8c44a 100644 --- a/gcc/gimple-harden-conditionals.cc +++ b/gcc/gimple-harden-conditionals.cc @@ -509,10 +509,16 @@ pass_harden_compares::execute (function *fun) gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT); /* We wish to insert a cond_expr after the compare, so arrange - for it to be at the end of a block if it isn't. */ - if (!gsi_end_p (gsi_split)) + for it to be at the end of a block if it isn't, and for it + to have a single successor in case there's more than + one, as in PR104975. */ + if (!gsi_end_p (gsi_split) + || !single_succ_p (gsi_bb (gsi_split))) { - gsi_prev (&gsi_split); + if (!gsi_end_p (gsi_split)) + gsi_prev (&gsi_split); + else + gsi_split = gsi_last_bb (gsi_bb (gsi_split)); basic_block obb = gsi_bb (gsi_split); basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest; gsi_next (&gsi_split); diff --git a/gcc/testsuite/gcc.dg/pr104975.c b/gcc/testsuite/gcc.dg/pr104975.c new file mode 100644 index 0000000000000..04532fc444340 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr104975.c @@ -0,0 +1,20 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -fharden-compares -fno-inline -fno-ipa-pure-const" } */ + +__attribute__ ((pure, returns_twice)) int +bar (int); + +int +quux (void) +{ + return 0; +} + +int +foo (short int x) +{ + x = !x; + bar (quux ()); + + return x; +}