OpenE2K
/
binutils-gdb
12
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

x86: optimize away pointless segment overrides 

When optimizing there's no point keeping the segment overrides when we
warn about their presence in the first place.
This commit is contained in:
Jan Beulich 2020-02-14 14:03:19 +01:00
parent 514a8bb031
commit 92334ad2c6
4 changed files with 31 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
gas/ChangeLog
View File

@ -1,4 +1,11 @@
2020-02-XX Jan Beulich <jbeulich@suse.com>
2020-02-14 Jan Beulich <jbeulich@suse.com>
* config/tc-i386.c (process_operands): Drop ineffectual segment
overrides when optimizing.
* testsuite/gas/i386/lea-optimize.d: New.
* testsuite/gas/i386/i386.exp: Run new test.
2020-02-14 Jan Beulich <jbeulich@suse.com>
* config/tc-i386.c (process_operands): Also check insn prefix
for ineffectual segment override warning. Don't cover possible

11
gas/config/tc-i386.c
View File

@ -7165,10 +7165,17 @@ duplicate:
}
if ((i.seg[0] || i.prefix[SEG_PREFIX])
&& !quiet_warnings
&& i.tm.base_opcode == 0x8d /* lea */
&& !is_any_vex_encoding(&i.tm))
as_warn (_("segment override on `%s' is ineffectual"), i.tm.name);
{
if (!quiet_warnings)
as_warn (_("segment override on `%s' is ineffectual"), i.tm.name);
if (optimize)
{
i.seg[0] = NULL;
i.prefix[SEG_PREFIX] = 0;
}
}
/* If a segment was explicitly specified, and the specified segment
is not the default, use an opcode prefix to select it. If we

1
gas/testsuite/gas/i386/i386.exp
View File

@ -502,6 +502,7 @@ if [expr ([istarget "i*86-*-*"] || [istarget "x86_64-*-*"]) && [gas_32_check]]
run_list_test "optimize-6a" "-I${srcdir}/$subdir -march=+noavx -al"
run_dump_test "optimize-6b"
run_list_test "optimize-7" "-I${srcdir}/$subdir -march=+noavx2 -al"
run_dump_test "lea-optimize"
run_dump_test "align-branch-1a"
run_dump_test "align-branch-1b"
run_dump_test "align-branch-1c"

13
gas/testsuite/gas/i386/lea-optimize.d Normal file
View File

@ -0,0 +1,13 @@
#as: -O -q
#objdump: -dw
#name: i386 LEA-like segment overrride dropping
#source: lea.s
.*: +file format .*
Disassembly of section .text:
0+ <start>:
[ ]*[0-9a-f]+:[ ]+8d 00[ ]+lea[ ]+\(%eax\),%eax
[ ]*[0-9a-f]+:[ ]+8d 00[ ]+lea[ ]+\(%eax\),%eax
#pass