[committed 1/5] MIPS16/GAS: Improve disallowed relocation operand error diagnostics

["Maciej W. Rozycki" <macro at imgtec dot com>]

Improve disallowed relocation operand error diagnostics for MIPS16 code 
and make it match corresponding regular MIPS and microMIPS handling, 
e.g:

$ cat sltu.s
	sltu	$2, %lo(foo)
$ as -o sltu.o sltu.s
sltu.s: Assembler messages:
sltu.s:1: Error: operand 2 must be constant `sltu $2,%lo(foo)'
$ as -mips16 -o sltu.o sltu.s
sltu.s: Assembler messages:
sltu.s:1: Error: invalid operands `sltu $2,%lo(foo)'
$

To do so call `match_not_constant' from `match_mips16_insn' whenever a 
disallowed relocation operation has been noticed, like `match_const_int'
does, making reporting consistent:

$ as -mips16 -o sltu.o sltu.s
sltu.s: Assembler messages:
sltu.s:1: Error: operand 2 must be constant `sltu $2,%lo(foo)'
$ 

	gas/
	* config/tc-mips.c (match_mips16_insn): Call 
	`match_not_constant' for a disallowed relocation operation.
	* testsuite/gas/mips/mips16-reloc-error.d: New test.
	* testsuite/gas/mips/mips16-reloc-error.l: New stderr output.
	* testsuite/gas/mips/mips16-reloc-error.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new test.
---
binutils-mips16-gas-not-const-err.diff
Index: binutils/gas/config/tc-mips.c
===================================================================
--- binutils.orig/gas/config/tc-mips.c	2017-05-12 08:47:14.978493693 +0100
+++ binutils/gas/config/tc-mips.c	2017-05-12 13:21:55.457157986 +0100
@@ -8259,7 +8259,10 @@ match_mips16_insn (struct mips_cl_insn *
 		 been allowed to take relocation operators.  */
 	      if (offset_reloc[0] != BFD_RELOC_UNUSED
 		  && (ext_operand->size != 16 || c == '8'))
-		return FALSE;
+		{
+		  match_not_constant (&arg);
+		  return FALSE;
+		}
 
 	      relax_char = c;
 	      continue;
Index: binutils/gas/testsuite/gas/mips/mips.exp
===================================================================
--- binutils.orig/gas/testsuite/gas/mips/mips.exp	2017-05-12 08:45:42.614003991 +0100
+++ binutils/gas/testsuite/gas/mips/mips.exp	2017-05-12 13:21:55.470317153 +0100
@@ -967,6 +967,8 @@ if { [istarget mips*-*-vxworks*] } {
 	run_dump_test "mips16-hilo-n32"
     }
     run_dump_test "mips16-hilo-match"
+    run_dump_test "mips16-reloc-error"
+
     run_dump_test "delay"
     run_dump_test "nodelay"
     run_dump_test "mips4010"
Index: binutils/gas/testsuite/gas/mips/mips16-reloc-error.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/mips16-reloc-error.d	2017-05-12 10:44:47.552787860 +0100
@@ -0,0 +1,3 @@
+#name: MIPS16 relocation errors
+#as: -32 -mips64r2
+#error-output: mips16-reloc-error.l
Index: binutils/gas/testsuite/gas/mips/mips16-reloc-error.l
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/mips16-reloc-error.l	2017-05-12 08:50:06.106927914 +0100
@@ -0,0 +1,28 @@
+.*: Assembler messages:
+.*:11: Error: operand 3 must be constant `addiu \$3,\$2,%lo\(bar\)'
+.*:12: Error: operand 3 must be constant `daddiu \$3,\$2,%lo\(bar\)'
+.*:14: Error: operand 2 must be constant `slti \$3,%lo\(bar\)'
+.*:15: Error: operand 2 must be constant `sltiu \$3,%lo\(bar\)'
+.*:17: Error: operand 3 must be constant `sll \$3,\$2,%lo\(bar\)'
+.*:18: Error: operand 3 must be constant `sra \$3,\$2,%lo\(bar\)'
+.*:19: Error: operand 3 must be constant `srl \$3,\$2,%lo\(bar\)'
+.*:20: Error: operand 3 must be constant `dsll \$3,\$2,%lo\(bar\)'
+.*:21: Error: operand 2 must be constant `dsra \$3,%lo\(bar\)'
+.*:22: Error: operand 2 must be constant `dsrl \$3,%lo\(bar\)'
+.*:24: Error: operand 1 must be constant `break %lo\(bar\)'
+.*:25: Error: operand 1 must be constant `sdbbp %lo\(bar\)'
+.*:27: Error: invalid operands `b %lo\(bar\)'
+.*:28: Error: invalid operands `beqz \$3,%lo\(bar\)'
+.*:29: Error: invalid operands `bnez \$3,%lo\(bar\)'
+.*:30: Error: invalid operands `bteqz %lo\(bar\)'
+.*:31: Error: invalid operands `btnez %lo\(bar\)'
+.*:33: Error: invalid operands `jal %lo\(bar\)'
+.*:34: Error: invalid operands `jalx %lo\(bar\)'
+.*:36: Error: operand 3 must be constant `save \$31,\$16,%lo\(bar\)'
+.*:37: Error: operand 3 must be constant `restore \$31,\$16,%lo\(bar\)'
+.*:39: Error: operand 6 must be constant `asmacro 0,0,0,0,0,%lo\(bar\)'
+.*:40: Error: operand 5 must be constant `asmacro 0,0,0,0,%lo\(bar\),0'
+.*:41: Error: operand 4 must be constant `asmacro 0,0,0,%lo\(bar\),0,0'
+.*:42: Error: operand 3 must be constant `asmacro 0,0,%lo\(bar\),0,0,0'
+.*:43: Error: operand 2 must be constant `asmacro 0,%lo\(bar\),0,0,0,0'
+.*:44: Error: operand 1 must be constant `asmacro %lo\(bar\),0,0,0,0,0'
Index: binutils/gas/testsuite/gas/mips/mips16-reloc-error.s
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/mips16-reloc-error.s	2017-05-12 08:50:06.127143451 +0100
@@ -0,0 +1,52 @@
+	.text
+
+	.set	bar, 8
+
+	.ent	foo
+	.set	mips16
+foo:
+	li	$2, %hi(bar)
+	sll	$2, $2, 16
+
+	addiu	$3, $2, %lo(bar)
+	daddiu	$3, $2, %lo(bar)
+
+	slti	$3, %lo(bar)
+	sltiu	$3, %lo(bar)
+
+	sll	$3, $2, %lo(bar)
+	sra	$3, $2, %lo(bar)
+	srl	$3, $2, %lo(bar)
+	dsll	$3, $2, %lo(bar)
+	dsra	$3, %lo(bar)
+	dsrl	$3, %lo(bar)
+
+	break	%lo(bar)
+	sdbbp	%lo(bar)
+
+	b	%lo(bar)
+	beqz	$3, %lo(bar)
+	bnez	$3, %lo(bar)
+	bteqz	%lo(bar)
+	btnez	%lo(bar)
+
+	jal	%lo(bar)
+	jalx	%lo(bar)
+
+	save	$31, $16, %lo(bar)
+	restore	$31, $16, %lo(bar)
+
+	asmacro	0, 0, 0, 0, 0, %lo(bar)
+	asmacro	0, 0, 0, 0, %lo(bar), 0
+	asmacro	0, 0, 0, %lo(bar), 0, 0
+	asmacro	0, 0, %lo(bar), 0, 0, 0
+	asmacro	0, %lo(bar), 0, 0, 0, 0
+	asmacro	%lo(bar), 0, 0, 0, 0, 0
+
+	nop
+	.set	nomips16
+	.end	foo
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align	4, 0
+	.space	16