[binutils-gdb] gas: leave expression symbols alone when processing equates
Jan Beulich
jbeulich@sourceware.org
Fri Mar 7 07:32:11 GMT 2025
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9479e1deba8c30f7756f1d1d8a219d6ee0e570d9
commit 9479e1deba8c30f7756f1d1d8a219d6ee0e570d9
Author: Jan Beulich <jbeulich@suse.com>
Date: Fri Mar 7 08:30:36 2025 +0100
gas: leave expression symbols alone when processing equates
PR gas/32721
In this bogus piece of code distilled from fuzzing and slightly edited:
A=%eax|%!
Y=A
Z=A
or $6,Z
the first of the equates with A on the rhs changes A's section (due to
the use of S_GET_VALUE()), from expression to register, thus yielding Y
in the expression section (and X_op being O_symbol), but Z in the
register section (and X_op being O_register with X_add_value being -1).
There shouldn't be random O_register expressions, though, for targets
setting md_register_arithmetic to false. Plus both Y and Z would better
be exchangeable.
In pseudo_set() wire handling of O_symbol expressions referencing a
symbol in the expression section to that of other stuff ending up in
this section.
Also avoid bogus O_register expressions to be created, for targets
setting md_register_arithmetic to false: S_GET_VALUE() would resolve
any arithmetic, which must not happen for such targets. To be on the
safe side for such targets, also amend resolve_register(). Correct
another earlier oversight there too (affecting at least Z80), by using
the new expr_copy() helper there as well.
Undo 46b9f07dfe79 ("PR 32721, internal error in
tc-i386.c:parse_register"), albeit without losing the simplification it
did.
Diff:
---
gas/config/tc-i386.c | 4 ++--
gas/expr.c | 27 ++++++++++++++++++++++++---
gas/read.c | 3 +++
gas/testsuite/gas/i386/i386.exp | 3 +++
gas/testsuite/gas/i386/pr32721.l | 7 +++++++
gas/testsuite/gas/i386/pr32721.s | 7 +++++++
6 files changed, 46 insertions(+), 5 deletions(-)
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 2aab0e99f01..3879001ee9e 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -16847,9 +16847,9 @@ parse_register (const char *reg_string, char **end_op)
{
const expressionS *e = symbol_get_value_expression (symbolP);
- if (e->X_op == O_register
- && (valueT) e->X_add_number < i386_regtab_size)
+ if (e->X_op == O_register)
{
+ know ((valueT) e->X_add_number < i386_regtab_size);
r = i386_regtab + e->X_add_number;
*end_op = (char *) reg_string + (input_line_pointer - buf);
}
diff --git a/gas/expr.c b/gas/expr.c
index 099be4361b4..bf58fc3a768 100644
--- a/gas/expr.c
+++ b/gas/expr.c
@@ -769,6 +769,16 @@ expr_build_dot (void)
return expr_build_uconstant (abs_section_offset);
}
+/* Copy an expression, preserving X_md. */
+
+static void expr_copy (expressionS *dst, const expressionS *src)
+{
+ unsigned short md = dst->X_md;
+
+ *dst = *src;
+ dst->X_md = md;
+}
+
#ifndef md_register_arithmetic
# define md_register_arithmetic 1
#endif
@@ -1396,8 +1406,17 @@ operand (expressionS *expressionP, enum expr_mode mode)
}
else if (!expr_defer_p (mode) && segment == reg_section)
{
- expressionP->X_op = O_register;
- expressionP->X_add_number = S_GET_VALUE (symbolP);
+ if (md_register_arithmetic)
+ {
+ expressionP->X_op = O_register;
+ expressionP->X_add_number = S_GET_VALUE (symbolP);
+ }
+ else
+ {
+ expr_copy (expressionP,
+ symbol_get_value_expression (symbolP));
+ resolve_register (expressionP);
+ }
}
else
{
@@ -2489,6 +2508,8 @@ void resolve_register (expressionS *expP)
do
{
+ if (!md_register_arithmetic && e->X_add_number)
+ break;
sym = e->X_add_symbol;
acc += e->X_add_number;
e = symbol_get_value_expression (sym);
@@ -2497,7 +2518,7 @@ void resolve_register (expressionS *expP)
if (e->X_op == O_register)
{
- *expP = *e;
+ expr_copy (expP, e);
expP->X_add_number += acc;
}
}
diff --git a/gas/read.c b/gas/read.c
index e451721aff9..2acb4e03a7f 100644
--- a/gas/read.c
+++ b/gas/read.c
@@ -4111,6 +4111,8 @@ pseudo_set (symbolS *symbolP)
case O_symbol:
seg = S_GET_SEGMENT (exp.X_add_symbol);
+ if (seg == expr_section)
+ goto expr;
/* For x=undef+const, create an expression symbol.
For x=x+const, just update x except when x is an undefined symbol
For x=defined+const, evaluate x. */
@@ -4142,6 +4144,7 @@ pseudo_set (symbolS *symbolP)
break;
default:
+ expr:
/* The value is some complex expression. */
S_SET_SEGMENT (symbolP, expr_section);
symbol_set_value_expression (symbolP, &exp);
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 329efc71b01..9b51d4946e2 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -848,6 +848,9 @@ run_list_test "unspec" ""
run_dump_test "fp"
run_dump_test "cond"
run_dump_test pr30248
+if {![is_aout_format]} then {
+ run_list_test pr32721 ""
+}
if {[is_elf_format] || [istarget "*-*-vxworks*"]} then {
run_list_test_stdin "list-1" "-al"
run_list_test_stdin "list-2" "-al"
diff --git a/gas/testsuite/gas/i386/pr32721.l b/gas/testsuite/gas/i386/pr32721.l
new file mode 100644
index 00000000000..54532bc5c3c
--- /dev/null
+++ b/gas/testsuite/gas/i386/pr32721.l
@@ -0,0 +1,7 @@
+.*: Assembler messages:
+.*:1: Error: bad expression
+.*:1: Warning: missing operand; zero assumed
+.*:1: Error: invalid operands .* for `|'
+#?.*: Error: invalid operands .* when setting .*
+#?.*: Error: invalid operands .* when setting .*
+#?.*: Error: invalid operands .* when setting .*
diff --git a/gas/testsuite/gas/i386/pr32721.s b/gas/testsuite/gas/i386/pr32721.s
new file mode 100644
index 00000000000..c66e3710514
--- /dev/null
+++ b/gas/testsuite/gas/i386/pr32721.s
@@ -0,0 +1,7 @@
+ A=%eax|%!
+ Y=A
+ Z=A
+
+ .text
+pr32721:
+ orl $6,Z
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