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x86: adjust NOP generation after potential non-insn

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Just like avoiding to do certain transformations potentially affected by
stand-alone prefixes or direct data emission, also avoid emitting
optimized NOPs right afterwards; insert a plain old NOP first in such
cases.
This commit is contained in:
Jan Beulich 2023-12-01 08:29:11 +01:00
parent ce69d08114
commit 0aa5d0c9e9
2 changed files with 13 additions and 1 deletions
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8
gas/config/tc-i386.c
View File

@ -1529,6 +1529,14 @@ i386_generate_nops (fragS *fragP, char *where, offsetT count, int limit)
else if (fragP->fr_type != rs_machine_dependent)
fragP->fr_var = count;
/* Emit a plain NOP first when the last thing we saw may not have been
a proper instruction (e.g. a stand-alone prefix or .byte). */
if (!fragP->tc_frag_data.last_insn_normal)
{
*where++ = 0x90;
--count;
}
if ((count / max_single_nop_size) > max_number_of_nops)
{
/* Generate jump over NOPs. */

6
gas/config/tc-i386.h
View File

@ -321,6 +321,7 @@ struct i386_tc_frag_data
unsigned int branch_type : 3;
unsigned int cpunop : 1;
unsigned int isanop : 1;
unsigned int last_insn_normal : 1;
};
/* We need to emit the right NOP pattern in .align frags. This is
@ -347,7 +348,10 @@ struct i386_tc_frag_data
(FRAGP)->tc_frag_data.cmp_size = 0; \
(FRAGP)->tc_frag_data.classified = 0; \
(FRAGP)->tc_frag_data.branch_type = 0; \
(FRAGP)->tc_frag_data.mf_type = 0; \
(FRAGP)->tc_frag_data.mf_type = 0; \
(FRAGP)->tc_frag_data.last_insn_normal \
= (seg_info(now_seg)->tc_segment_info_data.last_insn.kind \
== last_insn_other); \
} \
while (0)