From f62d3527db908646a518b1c1412210a3ae645d73 Mon Sep 17 00:00:00 2001 From: Martin Liska Date: Fri, 8 Mar 2019 13:55:40 +0100 Subject: [PATCH] x86: Disable jump tables when retpolines are used (PR target/86952). 2019-03-08 Martin Liska PR target/86952 * config/i386/i386.c (ix86_option_override_internal): Disable jump tables when retpolines are used. 2019-03-08 Martin Liska PR target/86952 * gcc.target/i386/pr86952.c: New test. * gcc.target/i386/indirect-thunk-7.c: Use jump tables to match scanned pattern. * gcc.target/i386/indirect-thunk-inline-7.c: Likewise. From-SVN: r269492 --- gcc/ChangeLog | 6 ++++++ gcc/config/i386/i386.c | 6 ++++++ gcc/testsuite/ChangeLog | 8 ++++++++ gcc/testsuite/gcc.target/i386/indirect-thunk-7.c | 2 +- .../gcc.target/i386/indirect-thunk-inline-7.c | 2 +- gcc/testsuite/gcc.target/i386/pr86952.c | 23 ++++++++++++++++++++++ 6 files changed, 45 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr86952.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index de7bdde..5e737bd 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2019-03-08 Martin Liska + + PR target/86952 + * config/i386/i386.c (ix86_option_override_internal): Disable + jump tables when retpolines are used. + 2019-03-08 Jan Hubicka PR go/63560 diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 2d6a993..319caed 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -4894,6 +4894,12 @@ ix86_option_override_internal (bool main_args_p, opts->x_param_values, opts_set->x_param_values); + /* PR86952: jump table usage with retpolines is slow. + The PR provides some numbers about the slowness. */ + if (ix86_indirect_branch != indirect_branch_keep + && !opts_set->x_flag_jump_tables) + opts->x_flag_jump_tables = 0; + return true; } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 4010924..9d386f6 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,11 @@ +2019-03-08 Martin Liska + + PR target/86952 + * gcc.target/i386/pr86952.c: New test. + * gcc.target/i386/indirect-thunk-7.c: Use jump tables to match + scanned pattern. + * gcc.target/i386/indirect-thunk-inline-7.c: Likewise. + 2019-03-08 Jakub Jelinek PR c++/89585 diff --git a/gcc/testsuite/gcc.target/i386/indirect-thunk-7.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-7.c index 3c72036..53868f4 100644 --- a/gcc/testsuite/gcc.target/i386/indirect-thunk-7.c +++ b/gcc/testsuite/gcc.target/i386/indirect-thunk-7.c @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk -fno-pic" } */ +/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk -fno-pic -fjump-tables" } */ void func0 (void); void func1 (void); diff --git a/gcc/testsuite/gcc.target/i386/indirect-thunk-inline-7.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-inline-7.c index ea00924..e6f0649 100644 --- a/gcc/testsuite/gcc.target/i386/indirect-thunk-inline-7.c +++ b/gcc/testsuite/gcc.target/i386/indirect-thunk-inline-7.c @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk-inline -fno-pic" } */ +/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk-inline -fno-pic -fjump-tables" } */ void func0 (void); void func1 (void); diff --git a/gcc/testsuite/gcc.target/i386/pr86952.c b/gcc/testsuite/gcc.target/i386/pr86952.c new file mode 100644 index 0000000..3ff3e35 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr86952.c @@ -0,0 +1,23 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mindirect-branch=thunk -fdump-tree-switchlower1" } */ + +int global; + +int +foo (int x) +{ + switch (x & 7) + { + case 0: ; return 1722; + case 1: global += 1; return 1060; + case 2: ; return 1990; + case 3: ; return 1242; + case 4: ; return 1466; + case 5: ; return 894; + case 6: ; return 570; + case 7: ; return 572; + default: return 0; + } +} + +/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: 1 2 3 4 5 6 7" "switchlower1" } } */ -- 2.7.4