On 3/28/19 9:52 AM, Martin Liška wrote:
> Hi.
>
> Backporting one documentation fix.
>
> Martin
>
One more patch that I'm going to backport.
Martin
>From a096ce6d9f8e636815af5a237881e1ba443f1b18 Mon Sep 17 00:00:00 2001
From: marxin <marxin@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 8 Mar 2019 12:55:40 +0000
Subject: [PATCH] Backport r269492
gcc/ChangeLog:
2019-03-08 Martin Liska <mli...@suse.cz>
PR target/86952
* config/i386/i386.c (ix86_option_override_internal): Disable
jump tables when retpolines are used.
gcc/testsuite/ChangeLog:
2019-03-08 Martin Liska <mli...@suse.cz>
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.
---
gcc/config/i386/i386.c | 6 +++++
.../gcc.target/i386/indirect-thunk-7.c | 2 +-
.../gcc.target/i386/indirect-thunk-extern-7.c | 2 +-
.../gcc.target/i386/indirect-thunk-inline-7.c | 2 +-
gcc/testsuite/gcc.target/i386/pr86952.c | 23 +++++++++++++++++++
5 files changed, 32 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr86952.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 18dce38640b..96bdb3a78ba 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -6282,6 +6282,12 @@ ix86_option_override_internal (bool main_args_p,
target_option_default_node = target_option_current_node
= build_target_option_node (opts);
+ /* 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/gcc.target/i386/indirect-thunk-7.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-7.c
index 3c72036dbaf..53868f46558 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-extern-7.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-extern-7.c
index 2b9a33e93dc..bc185fe98af 100644
--- a/gcc/testsuite/gcc.target/i386/indirect-thunk-extern-7.c
+++ b/gcc/testsuite/gcc.target/i386/indirect-thunk-extern-7.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk-extern -fno-pic" } */
+/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk-extern -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 ea009245a58..e6f064959a1 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 00000000000..004e167add0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr86952.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mindirect-branch=thunk" } */
+
+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-assembler-not "jmp\[ \t\]\\*" } } */
--
2.21.0
