From 4faaa10f3fabb345aca006ed67a8be97dc924e9c Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Wed, 23 Mar 2022 12:28:53 +0100
Subject: [PATCH] x86: don't attempt to resolve equates and alike from
 i386_parse_name()

PR gas/28977

Perhaps right from its introduction in 4d1bb7955a8b it was wrong for
i386_parse_name() to call parse_register(). This being a hook from the
expression parser, it shouldn't be resolving e.g. equated symbols.
That's relevant only for all other callers of parse_register().

To compensate, in Intel syntax mode check_register() needs calling;
perhaps not doing so was an oversight right when the function was
introduced. This is necessary in particular to force EVEX encoding when
VRex registers are used (but of course also to reject bad uses of
registers, i.e. fully matching what parse_register() needs it for).
---
 gas/config/tc-i386-intel.c      |  7 +++++++
 gas/config/tc-i386.c            |  5 +++--
 gas/testsuite/gas/i386/equ-2.l  | 17 +++++++++++++++++
 gas/testsuite/gas/i386/equ-2.s  | 11 +++++++++++
 gas/testsuite/gas/i386/i386.exp |  1 +
 5 files changed, 39 insertions(+), 2 deletions(-)
 create mode 100644 gas/testsuite/gas/i386/equ-2.l
 create mode 100644 gas/testsuite/gas/i386/equ-2.s

diff --git a/gas/config/tc-i386-intel.c b/gas/config/tc-i386-intel.c
index 42f0afe0e41..d0c30ddbd5d 100644
--- a/gas/config/tc-i386-intel.c
+++ b/gas/config/tc-i386-intel.c
@@ -289,6 +289,13 @@ i386_intel_simplify_register (expressionS *e)
       return 0;
     }
 
+  if (!check_register (&i386_regtab[reg_num]))
+    {
+      as_bad (_("register '%s%s' cannot be used here"),
+	      register_prefix, i386_regtab[reg_num].reg_name);
+      return 0;
+    }
+
   if (!intel_state.in_bracket)
     {
       if (i.op[this_operand].regs)
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index afb8b706bda..aea19aa5d88 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -13000,11 +13000,12 @@ parse_register (char *reg_string, char **end_op)
 int
 i386_parse_name (char *name, expressionS *e, char *nextcharP)
 {
-  const reg_entry *r;
+  const reg_entry *r = NULL;
   char *end = input_line_pointer;
 
   *end = *nextcharP;
-  r = parse_register (name, &input_line_pointer);
+  if (*name == REGISTER_PREFIX || allow_naked_reg)
+    r = parse_real_register (name, &input_line_pointer);
   if (r && end <= input_line_pointer)
     {
       *nextcharP = *input_line_pointer;
diff --git a/gas/testsuite/gas/i386/equ-2.l b/gas/testsuite/gas/i386/equ-2.l
new file mode 100644
index 00000000000..97a24b531b3
--- /dev/null
+++ b/gas/testsuite/gas/i386/equ-2.l
@@ -0,0 +1,17 @@
+.*: Assembler messages:
+.*:8: Error: .*
+#...
+GAS LISTING .*
+
+
+[ 	]*[0-9]+[ 	]+# .*
+[ 	]*[0-9]+[ 	]+equ:
+[ 	]*[0-9]+[ 	]+s = %edx % %ecx
+[ 	]*[0-9]+[ 	]+x = s
+[ 	]*[0-9]+[ 	]+y = s
+[ 	]*[0-9]+[ 	]+z = s
+[ 	]*[0-9]+[ 	]*
+[ 	]*[0-9]+[ 	]+t = %ymm5%%%!%%%%!%%%%%%%%!%ebp%%%%%%%%%%%%%%%%%%M
+[ 	]*[0-9]+[ 	]+a = t
+[ 	]*[0-9]+[ 	]+b = t
+[ 	]*[0-9]+[ 	]+c = t
diff --git a/gas/testsuite/gas/i386/equ-2.s b/gas/testsuite/gas/i386/equ-2.s
new file mode 100644
index 00000000000..87ec9a78d1d
--- /dev/null
+++ b/gas/testsuite/gas/i386/equ-2.s
@@ -0,0 +1,11 @@
+# PR gas/28977
+equ:
+	s = %edx % %ecx
+	x = s
+	y = s
+	z = s
+
+	t = %ymm5%%%!%%%%!%%%%%%%%!%ebp%%%%%%%%%%%%%%%%%%M
+	a = t
+	b = t
+	c = t
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 3c157e9eb1e..96356d3eb11 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -99,6 +99,7 @@ if [gas_32_check] then {
     run_list_test "suffix-bad"
     run_dump_test "immed32"
     run_dump_test "equ"
+    run_list_test "equ-2" "-al"
     run_list_test "equ-bad"
     run_dump_test "divide"
     run_dump_test "quoted"
-- 
2.30.2