LoongArch: add .option directive

In some cases we may want to use different options only for certain
assembly, so the .option directive is added to control the assembler
options.

.option can accept 4 parameters:

push
pop
  Pushes or pops the current option stack. They limit the scope of
  option changes so that they do not affect other parts of the assembly
  file.

relax
norelax
  Enables or disables relaxation.

gas/config/tc-loongarch.c

@@ -541,6 +541,64 @@ s_dtprel (int bytes)
   demand_empty_rest_of_line ();
 }
 
+struct LARCH_option_stack
+{
+  struct LARCH_option_stack *next;
+  struct loongarch_ASEs_option options;
+};
+
+static struct LARCH_option_stack *LARCH_opts_stack = NULL;
+
+/* Handle the .option pseudo-op.
+   The alignment of .align is done by R_LARCH_ALIGN at link time.
+   If the .align directive is within the range controlled by
+   .option norelax, that is, relax is turned off, R_LARCH_ALIGN
+   cannot be generated, which may cause ld to be unable to handle
+   the alignment.  */
+static void
+s_loongarch_option (int x ATTRIBUTE_UNUSED)
+{
+  char *name = input_line_pointer, ch;
+  while (!is_end_of_line[(unsigned char) *input_line_pointer])
+    ++input_line_pointer;
+  ch = *input_line_pointer;
+  *input_line_pointer = '\0';
+
+  if (strcmp (name, "relax") == 0)
+    LARCH_opts.relax = 1;
+  else if (strcmp (name, "norelax") == 0)
+    LARCH_opts.relax = 0;
+  else if (strcmp (name, "push") == 0)
+    {
+      struct LARCH_option_stack *s;
+
+      s = XNEW (struct LARCH_option_stack);
+      s->next = LARCH_opts_stack;
+      s->options = LARCH_opts;
+      LARCH_opts_stack = s;
+    }
+  else if (strcmp (name, "pop") == 0)
+    {
+      struct LARCH_option_stack *s;
+
+      s = LARCH_opts_stack;
+      if (s == NULL)
+	as_bad (_(".option pop with no .option push"));
+      else
+	{
+	  LARCH_opts_stack = s->next;
+	  LARCH_opts = s->options;
+	  free (s);
+	}
+    }
+  else
+    {
+      as_warn (_("unrecognized .option directive: %s"), name);
+    }
+  *input_line_pointer = ch;
+  demand_empty_rest_of_line ();
+}
+
 static const pseudo_typeS loongarch_pseudo_table[] =
 {
   { "dword", cons, 8 },
@@ -548,6 +606,7 @@ static const pseudo_typeS loongarch_pseudo_table[] =
   { "half", cons, 2 },
   { "dtprelword", s_dtprel, 4 },
   { "dtpreldword", s_dtprel, 8 },
+  { "option", s_loongarch_option, 0},
   { NULL, NULL, 0 },
 };
 

gas/testsuite/gas/loongarch/loongarch.exp

@@ -35,5 +35,6 @@ if [istarget loongarch*-*-*] {
 
   if [istarget loongarch64-*-*] {
     run_list_test "illegal-operand"
+    run_list_test "pseudo_op_option_fail"
   }
 }

gas/testsuite/gas/loongarch/pseudo_op_option.d

@@ -0,0 +1,36 @@
+#as: -mrelax
+#objdump: -dr
+#skip: loongarch32-*-*
+
+.*:     file format .*
+
+
+Disassembly of section .text:
+
+0.* <.text>:
+   0:	1a000004 	pcalau12i   	\$a0, 0
+			0: R_LARCH_PCALA_HI20	x
+			0: R_LARCH_RELAX	\*ABS\*
+   4:	02c00084 	addi.d      	\$a0, \$a0, 0
+			4: R_LARCH_PCALA_LO12	x
+			4: R_LARCH_RELAX	\*ABS\*
+   8:	1a000004 	pcalau12i   	\$a0, 0
+			8: R_LARCH_PCALA_HI20	x
+   c:	02c00084 	addi.d      	\$a0, \$a0, 0
+			c: R_LARCH_PCALA_LO12	x
+  10:	1a000004 	pcalau12i   	\$a0, 0
+			10: R_LARCH_PCALA_HI20	x
+			10: R_LARCH_RELAX	\*ABS\*
+  14:	02c00084 	addi.d      	\$a0, \$a0, 0
+			14: R_LARCH_PCALA_LO12	x
+			14: R_LARCH_RELAX	\*ABS\*
+  18:	1a000004 	pcalau12i   	\$a0, 0
+			18: R_LARCH_PCALA_HI20	x
+  1c:	02c00084 	addi.d      	\$a0, \$a0, 0
+			1c: R_LARCH_PCALA_LO12	x
+  20:	1a000004 	pcalau12i   	\$a0, 0
+			20: R_LARCH_PCALA_HI20	x
+			20: R_LARCH_RELAX	\*ABS\*
+  24:	02c00084 	addi.d      	\$a0, \$a0, 0
+			24: R_LARCH_PCALA_LO12	x
+			24: R_LARCH_RELAX	\*ABS\*

gas/testsuite/gas/loongarch/pseudo_op_option.s

@@ -0,0 +1,19 @@
+# Gas enables relax by default.
+# Push and pop can be nested, and each pop restores the options before
+# the most recent push.
+	.text
+.L1:
+	la.pcrel  $a0,x
+
+	.option push
+	.option norelax
+	la.pcrel  $a0,x
+
+	.option push
+	.option relax
+	la.pcrel  $a0,x
+	.option pop
+
+	la.pcrel  $a0,x
+	.option pop
+	la.pcrel  $a0,x

gas/testsuite/gas/loongarch/pseudo_op_option_fail.l

@@ -0,0 +1,2 @@
+.*: Assembler messages:
+.*: Error: \.option pop with no \.option push

gas/testsuite/gas/loongarch/pseudo_op_option_fail.s

@@ -0,0 +1,2 @@
+	.text
+	.option pop