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binutils/SME-0009-aarch64-Check-for-register-aliases-before-mnemonics.patch
eastb233 af51a301bd AArch64: Support SME instructions
2024-03-08 15:14:40 +08:00

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From e4afe464b120e181747b1108a23e0da2d16abd99 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 30 Nov 2021 17:50:24 +0000
Subject: [PATCH 09/10] aarch64: Check for register aliases before mnemonics
Reference: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=2dd3146b4ffcb8528a6e093741ba31636afdf8ae
Previously we would not accept:
A .req B
if A happened to be the name of an instruction. Adding new
instructions could therefore invalidate existing register aliases.
I noticed this with a test that used "zero" as a register alias
for "xzr", where "zero" is now also the name of an SME instruction.
I don't have any evidence that "real" code is doing this, but it
seems at least plausible.
This patch switches things so that we check for register aliases
first. It might slow down parsing slightly, but the difference
is unlikely to be noticeable.
Things like:
b .req + 0
still work, since create_register_alias checks for " .req ",
and with the input scrubber, we'll only keep whitespace after
.req if it's followed by another name. If there's some valid
expression that I haven't thought about that is scrubbed to
" .req ", users could avoid the ambiguity by wrapping .req
in parentheses.
The new test for invalid aliases already passed. I just wanted
something to exercise the !dot condition.
I can't find a way of exercising the (existing) p == base condition,
but I'm not brave enough to say that it can never happen. If it does
happen, get_mnemonic_name would return an empty string.
gas/
* config/tc-aarch64.c (opcode_lookup): Move mnemonic extraction
code to...
(md_assemble): ...here. Check for register aliases first.
* testsuite/gas/aarch64/register_aliases.d,
testsuite/gas/aarch64/register_aliases.s: Test for a register
alias called "zero".
* testsuite/gas/aarch64/register_aliases_invalid.d,
testsuite/gas/aarch64/register_aliases_invalid.l,
testsuite/gas/aarch64/register_aliases_invalid.s: New test.
---
gas/config/tc-aarch64.c | 62 +++++++++----------
gas/testsuite/gas/aarch64/register_aliases.d | 1 +
gas/testsuite/gas/aarch64/register_aliases.s | 3 +-
.../gas/aarch64/register_aliases_invalid.d | 1 +
.../gas/aarch64/register_aliases_invalid.l | 3 +
.../gas/aarch64/register_aliases_invalid.s | 2 +
6 files changed, 38 insertions(+), 34 deletions(-)
create mode 100644 gas/testsuite/gas/aarch64/register_aliases_invalid.d
create mode 100644 gas/testsuite/gas/aarch64/register_aliases_invalid.l
create mode 100644 gas/testsuite/gas/aarch64/register_aliases_invalid.s
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index ea58d9b0..c9677edc 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -5786,25 +5786,18 @@ lookup_mnemonic (const char *start, int len)
}
/* Subroutine of md_assemble, responsible for looking up the primary
- opcode from the mnemonic the user wrote. STR points to the
- beginning of the mnemonic. */
+ opcode from the mnemonic the user wrote. BASE points to the beginning
+ of the mnemonic, DOT points to the first '.' within the mnemonic
+ (if any) and END points to the end of the mnemonic. */
static templates *
-opcode_lookup (char **str)
+opcode_lookup (char *base, char *dot, char *end)
{
- char *end, *base, *dot;
const aarch64_cond *cond;
char condname[16];
int len;
- /* Scan up to the end of the mnemonic, which must end in white space,
- '.', or end of string. */
- dot = 0;
- for (base = end = *str; is_part_of_name(*end); end++)
- if (*end == '.' && !dot)
- dot = end;
-
- if (end == base || dot == base)
+ if (dot == end)
return 0;
inst.cond = COND_ALWAYS;
@@ -5813,23 +5806,13 @@ opcode_lookup (char **str)
if (dot)
{
cond = str_hash_find_n (aarch64_cond_hsh, dot + 1, end - dot - 1);
- if (cond)
- {
- inst.cond = cond->value;
- *str = end;
- }
- else
- {
- *str = dot;
- return 0;
- }
+ if (!cond)
+ return 0;
+ inst.cond = cond->value;
len = dot - base;
}
else
- {
- *str = end;
- len = end - base;
- }
+ len = end - base;
if (inst.cond == COND_ALWAYS)
{
@@ -7918,7 +7901,6 @@ dump_opcode_operands (const aarch64_opcode *opcode)
void
md_assemble (char *str)
{
- char *p = str;
templates *template;
const aarch64_opcode *opcode;
aarch64_inst *inst_base;
@@ -7941,14 +7923,28 @@ md_assemble (char *str)
DEBUG_TRACE ("==============================");
DEBUG_TRACE ("Enter md_assemble with %s", str);
- template = opcode_lookup (&p);
+ /* Scan up to the end of the mnemonic, which must end in whitespace,
+ '.', or end of string. */
+ char *p = str;
+ char *dot = 0;
+ for (; is_part_of_name (*p); p++)
+ if (*p == '.' && !dot)
+ dot = p;
+
+ if (p == str)
+ {
+ as_bad (_("unknown mnemonic -- `%s'"), str);
+ return;
+ }
+
+ if (!dot && create_register_alias (str, p))
+ return;
+
+ template = opcode_lookup (str, dot, p);
if (!template)
{
- /* It wasn't an instruction, but it might be a register alias of
- the form alias .req reg directive. */
- if (!create_register_alias (str, p))
- as_bad (_("unknown mnemonic `%s' -- `%s'"), get_mnemonic_name (str),
- str);
+ as_bad (_("unknown mnemonic `%s' -- `%s'"), get_mnemonic_name (str),
+ str);
return;
}
diff --git a/gas/testsuite/gas/aarch64/register_aliases.d b/gas/testsuite/gas/aarch64/register_aliases.d
index eab63870..8d614b47 100644
--- a/gas/testsuite/gas/aarch64/register_aliases.d
+++ b/gas/testsuite/gas/aarch64/register_aliases.d
@@ -10,3 +10,4 @@ Disassembly of section \.text:
8: f94003b1 ldr x17, \[x29\]
c: f90003b0 str x16, \[x29\]
10: f94003b1 ldr x17, \[x29\]
+ 14: f900001f str xzr, \[x0\]
diff --git a/gas/testsuite/gas/aarch64/register_aliases.s b/gas/testsuite/gas/aarch64/register_aliases.s
index fcd06507..856be569 100644
--- a/gas/testsuite/gas/aarch64/register_aliases.s
+++ b/gas/testsuite/gas/aarch64/register_aliases.s
@@ -3,9 +3,10 @@
fp .req x29
ip0 .req x16
ip1 .req x17
+ zero .req xzr
add ip0, ip0, lr
str ip0, [fp]
ldr ip1, [fp]
str IP0, [fp]
ldr IP1, [fp]
-
+ str zero, [x0]
diff --git a/gas/testsuite/gas/aarch64/register_aliases_invalid.d b/gas/testsuite/gas/aarch64/register_aliases_invalid.d
new file mode 100644
index 00000000..7c453ce0
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/register_aliases_invalid.d
@@ -0,0 +1 @@
+#error_output: register_aliases_invalid.l
diff --git a/gas/testsuite/gas/aarch64/register_aliases_invalid.l b/gas/testsuite/gas/aarch64/register_aliases_invalid.l
new file mode 100644
index 00000000..6350049d
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/register_aliases_invalid.l
@@ -0,0 +1,3 @@
+.*:
+.*: Error: unknown mnemonic `lr\.req' -- `lr\.req x30'
+.*: Error: unknown mnemonic `lr\.a' -- `lr\.a .req x30'
diff --git a/gas/testsuite/gas/aarch64/register_aliases_invalid.s b/gas/testsuite/gas/aarch64/register_aliases_invalid.s
new file mode 100644
index 00000000..2df2eaab
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/register_aliases_invalid.s
@@ -0,0 +1,2 @@
+lr.req x30
+lr.a .req x30
--
2.19.1
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