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BR 3392590: add warning for valid but obsolete instructions

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Just becase one is compiling for an old CPU doesn't mean one wants to
use obsolete instructions that would not be forward compatible. Rename
the "obsolete" warning to "obsolete-removed" and create a new
"obsolete-valid" warning to go with it (-w[+-]obsolete controls both
options, as usual.)

Suggested-by: C. Masloch <pushbx@38.de>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin (Intel) 2019-08-09 14:21:42 -07:00
parent 63cacad271
commit fb11889040
2 changed files with 25 additions and 6 deletions
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22
asm/assemble.c
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@ -782,21 +782,31 @@ int64_t assemble(int32_t segment, int64_t start, int bits, insn *instruction)
/* Matches! */
if (unlikely(itemp_has(temp, IF_OBSOLETE))) {
/*
* If IF_OBSOLETE is set, warn unless we have *exactly*
* the correct CPU level set.
* If IF_OBSOLETE is set, warn the user. Different
* warning classes for "obsolete but valid for this
* specific CPU" and "obsolete and gone."
*
*!obsolete [on] instruction obsolete for the target CPU
*! warns if an instruction which has been removed
*!obsolete-removed [on] instruction obsolete and removed on the target CPU
*! warns for an instruction which has been removed
*! from the architecture, and is no longer included
*! in the CPU definition given in the \c{[CPU]}
*! directive, for example \c{POP CS}, the opcode for
*! which, \c{0Fh}, instead is an opcode prefix on
*! CPUs newer than the first generation 8086.
*
*!obsolete-valid [on] instruction obsolete but valid on the target CPU
*! warns for an instruction which has been removed
*! from the architecture, but is still valid on the
*! specific CPU given in the \c{CPU} directive. Code
*! using these instructions is not forward compatible.
*/
if (iflag_cmp_cpu_level(&insns_flags[temp->iflag_idx], &cpu)) {
nasm_warn(WARN_OBSOLETE,
"obsolete instruction invalid on the target CPU");
nasm_warn(WARN_OBSOLETE_REMOVED,
"instruction obsolete and removed on the target CPU");
} else {
nasm_warn(WARN_OBSOLETE_VALID,
"instruction obsolete but valid on the target CPU");
}
}

9
test/obsolete.asm Normal file
View File

@ -0,0 +1,9 @@
bits 16
cpu 8086
pop cs
mov cs,ax
cpu 386
pop cs
mov cs,ax