From 64d23078e30e54e1bb095962540e4c6138edaf5a Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Wed, 23 Mar 2022 12:31:04 +0100
Subject: [PATCH] x86: improve resolution of register equates

Allow transitive (or recursive) equates to work in addition to direct
ones. The only requirements are that
- the equate being straight of a register, i.e. no expressions involved
  (albeit I'm afraid something like "%eax + 0" will be viewed as %eax),
- at the point of use there's no forward ref left which cannot be
  resolved, yet.
---
 gas/config/tc-i386-intel.c   |  3 +++
 gas/config/tc-i386.c         |  8 ++++++++
 gas/testsuite/gas/i386/equ.d |  6 ++++++
 gas/testsuite/gas/i386/equ.s | 14 ++++++++++++--
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/gas/config/tc-i386-intel.c b/gas/config/tc-i386-intel.c
index d0c30ddbd5d..83d22407429 100644
--- a/gas/config/tc-i386-intel.c
+++ b/gas/config/tc-i386-intel.c
@@ -536,6 +536,9 @@ static int i386_intel_simplify (expressionS *e)
       if (e->X_add_symbol
 	  && !i386_intel_simplify_symbol (e->X_add_symbol))
 	return 0;
+      if (!the_reg && this_operand >= 0
+	  && e->X_op == O_symbol && !e->X_add_number)
+	the_reg = i.op[this_operand].regs;
       if (e->X_op == O_add || e->X_op == O_subtract)
 	{
 	  base = intel_state.base;
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index ec82144ed1b..93eec1c9ed4 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -12974,6 +12974,14 @@ parse_register (char *reg_string, char **end_op)
       input_line_pointer = reg_string;
       c = get_symbol_name (&reg_string);
       symbolP = symbol_find (reg_string);
+      while (symbolP && S_GET_SEGMENT (symbolP) != reg_section)
+	{
+	  const expressionS *e = symbol_get_value_expression(symbolP);
+
+	  if (e->X_op != O_symbol || e->X_add_number)
+	    break;
+	  symbolP = e->X_add_symbol;
+	}
       if (symbolP && S_GET_SEGMENT (symbolP) == reg_section)
 	{
 	  const expressionS *e = symbol_get_value_expression (symbolP);
diff --git a/gas/testsuite/gas/i386/equ.d b/gas/testsuite/gas/i386/equ.d
index 0f270a6ccdf..d7c863f4560 100644
--- a/gas/testsuite/gas/i386/equ.d
+++ b/gas/testsuite/gas/i386/equ.d
@@ -13,6 +13,8 @@ Disassembly of section .text:
 [ 0-9a-f]+:[ 	0-9a-f]+test[ 	]+%ecx,%ecx
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+%fs:\(%ecx,%ecx,4\),%ecx
 [ 0-9a-f]+:[ 	0-9a-f]+fadd[ 	]+%st\(1\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fmul[ 	]+%st\(1\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fsub[ 	]+%st\(1\),%st
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+\$0xfffffffe,%eax
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+0xfffffffe,%eax
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+\$0x0,%eax[ 	0-9a-f]+:[ 	a-zA-Z0-9_]+xtrn
@@ -21,7 +23,11 @@ Disassembly of section .text:
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+%gs:\(%edx,%edx,8\),%edx
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+%gs:\(%edx,%edx,8\),%edx
 [ 0-9a-f]+:[ 	0-9a-f]+fadd[ 	]+%st\(1\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fmul[ 	]+%st\(1\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fsub[ 	]+%st\(1\),%st
 [ 0-9a-f]+:[ 	0-9a-f]+fadd[ 	]+%st\(7\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fmul[ 	]+%st\(7\),%st
+[ 0-9a-f]+:[ 	0-9a-f]+fsub[ 	]+%st\(7\),%st
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+0x4\(%edx\),%eax
 [ 0-9a-f]+:[ 	0-9a-f]+mov[ 	]+0x4\(%edx\),%eax
 #pass
diff --git a/gas/testsuite/gas/i386/equ.s b/gas/testsuite/gas/i386/equ.s
index e15148a741d..c7c4e604f03 100644
--- a/gas/testsuite/gas/i386/equ.s
+++ b/gas/testsuite/gas/i386/equ.s
@@ -13,8 +13,12 @@ _start:
  .equ s, %fs
 	testl	r, r
 	movl	s:(r,r,4), r
+ .equ z, y
+ .equ y, x
  .equ x, %st(1)
 	fadd	x
+	fmul	y
+	fsub	z
 
  .if r <> %ecx
  .err
@@ -37,8 +41,14 @@ _start:
 	mov	r, s:[r+r*8]
 	mov	r, s:[8*r+r]
 	fadd	x
- .equ x, st(7)
-	fadd	x
+	fmul	y
+	fsub	z
+ .equ c, b
+ .equ b, a
+ .equ a, st(7)
+	fadd	a
+	fmul	b
+	fsub	c
  .equ r, edx + 4
 	mov	eax, [r]
 	mov	eax, [r]
-- 
2.30.2