From: Jan Beulich Date: Fri, 1 Dec 2023 07:29:11 +0000 (+0100) Subject: x86: adjust NOP generation after potential non-insn X-Git-Tag: binutils-2_42~758 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0aa5d0c9e90a2bf26a99a0354ef500e971341de8;p=thirdparty%2Fbinutils-gdb.git x86: adjust NOP generation after potential non-insn 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. --- diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c index e984923ec35..4f3864f2ba7 100644 --- a/gas/config/tc-i386.c +++ b/gas/config/tc-i386.c @@ -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. */ diff --git a/gas/config/tc-i386.h b/gas/config/tc-i386.h index c3022149fbe..6d6f0b93681 100644 --- a/gas/config/tc-i386.h +++ b/gas/config/tc-i386.h @@ -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)