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From: Alexandre Oliva <aoliva@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/aoliva/heads/testme)] hardcfr: optionally disable in leaf functions Date: Thu, 8 Jun 2023 09:17:36 +0000 (GMT) [thread overview] Message-ID: <20230608091736.9B8A4385700B@sourceware.org> (raw) https://gcc.gnu.org/g:3334b477965df23c819f92118bdfd157d2832fbb commit 3334b477965df23c819f92118bdfd157d2832fbb Author: Alexandre Oliva <oliva@adacore.com> Date: Wed Oct 19 20:36:30 2022 -0300 hardcfr: optionally disable in leaf functions Introduce -fhardcfr-skip-leaf to avoid control flow redundancy instrumentation of leaf functions, where the benefit is far more limited. for gcc/ChangeLog * common.opt (fhardcfr-skip-leaf): New. * doc/invoke.texi: Document it. * gimple-harden-control-flow.cc (pass_harden_control_flow_redundancy::execute): Honor it. for gcc/testsuite/ChangeLog * c-c++-common/torture/harden-cfr-skip-leaf.c: New. Diff: --- gcc/common.opt | 4 ++++ gcc/doc/invoke.texi | 8 +++++-- gcc/gimple-harden-control-flow.cc | 27 ++++++++++++++++++++++ .../c-c++-common/torture/harden-cfr-skip-leaf.c | 10 ++++++++ 4 files changed, 47 insertions(+), 2 deletions(-) diff --git a/gcc/common.opt b/gcc/common.opt index 574299edace..feea4920c9d 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -1805,6 +1805,10 @@ fharden-control-flow-redundancy Common Var(flag_harden_control_flow_redundancy) Optimization Harden control flow by recording and checking execution paths. +fhardcfr-skip-leaf +Common Var(flag_harden_control_flow_redundancy_skip_leaf) Optimization +Disable CFR in leaf functions. + fhardcfr-check-returning-calls Common Var(flag_harden_control_flow_redundancy_check_returning_calls) Init(-1) Optimization Check CFR execution paths also before calls followed by returns of their results. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 3d9c5f753a4..2703a914dca 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -635,8 +635,8 @@ Objective-C and Objective-C++ Dialects}. -fsanitize-undefined-trap-on-error -fbounds-check -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]} -fharden-compares -fharden-conditional-branches --fharden-control-flow-redundancy -fhardcfr-check-exceptions --fhardcfr-check-returning-calls +-fharden-control-flow-redundancy -fhardcfr-skip-leaf +-fhardcfr-check-exceptions -fhardcfr-check-returning-calls -fhardcfr-check-noreturn-calls=@r{[}always@r{|}not-always@r{|}nothrow@r{|}never@r{]} -fstack-protector -fstack-protector-all -fstack-protector-strong -fstack-protector-explicit -fstack-check @@ -17263,6 +17263,10 @@ would also have verification issued before the call, but these possibilities are merely theoretical, as these conditions can only be met when using custom compiler plugins. +@opindex fhardcfr-skip-leaf +@item -fhardcfr-skip-leaf +Disable @option{-fharden-control-flow-redundancy} in leaf functions. + @opindex fhardcfr-check-exceptions @opindex fno-hardcfr-check-exceptions @item -fhardcfr-check-exceptions diff --git a/gcc/gimple-harden-control-flow.cc b/gcc/gimple-harden-control-flow.cc index 3e6fe2db479..3998fd0d293 100644 --- a/gcc/gimple-harden-control-flow.cc +++ b/gcc/gimple-harden-control-flow.cc @@ -1114,6 +1114,33 @@ pass_harden_control_flow_redundancy::execute (function *fun) basic_block bb; basic_block bb_eh_cleanup = NULL; + if (flag_harden_control_flow_redundancy_skip_leaf) + { + bool found_calls_p = false; + + FOR_EACH_BB_FN (bb, fun) + { + for (gimple_stmt_iterator gsi = gsi_last_bb (bb); + !gsi_end_p (gsi); gsi_prev (&gsi)) + if (is_a <gcall *> (gsi_stmt (gsi))) + { + found_calls_p = true; + break; + } + if (found_calls_p) + break; + } + + if (!found_calls_p) + { + if (dump_file) + fprintf (dump_file, + "Disabling CFR for leaf function, as requested\n"); + + return 0; + } + } + if (check_at_escaping_exceptions) { int lp_eh_cleanup = -1; diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-skip-leaf.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-skip-leaf.c new file mode 100644 index 00000000000..85ecaa04d04 --- /dev/null +++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-skip-leaf.c @@ -0,0 +1,10 @@ +/* { dg-do run } */ +/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-skip-leaf -fdump-tree-hardcfr -ffat-lto-objects" } */ + +/* Test skipping instrumentation of leaf functions. */ + +#include "harden-cfr.c" + +/* { dg-final { scan-tree-dump-times "__builtin_trap" 0 "hardcfr" } } */ +/* Only main isn't leaf. */ +/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
next reply other threads:[~2023-06-08 9:17 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-08 9:17 Alexandre Oliva [this message] -- strict thread matches above, loose matches on Subject: below -- 2023-06-23 20:13 Alexandre Oliva 2023-06-09 8:07 Alexandre Oliva 2023-06-09 6:17 Alexandre Oliva 2023-06-08 10:59 Alexandre Oliva 2023-06-08 10:43 Alexandre Oliva 2023-06-08 4:48 Alexandre Oliva 2022-10-25 2:52 Alexandre Oliva 2022-10-20 22:32 Alexandre Oliva 2022-10-20 5:46 Alexandre Oliva 2022-10-20 4:09 Alexandre Oliva
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