MIPS16/GAS: Fix assertion failures with relocations on 16-bit instructions

Complement commit c9775dde3277 ("MIPS16: Add R_MIPS16_PC16_S1 branch
relocation support)" and report an assembly error when a relocation is
required for an instruction, currently a branch only, that has been
forced to use its unextended encoding, either with the use of an
explicit `.t' mnemonic suffix, or by means of `.set noautoextend' being
active, fixing an assertion failure currently caused instead.

	gas/
	* config/tc-mips.c (md_convert_frag): Report an error instead of
	asserting on `ext'.
	* testsuite/gas/mips/mips16-branch-unextended-1.d: New test.
	* testsuite/gas/mips/mips16-branch-unextended-2.d: New test.
	* testsuite/gas/mips/mips16-branch-unextended-1.s: New test
	source.
	* testsuite/gas/mips/mips16-branch-unextended-2.s: New test.
	* testsuite/gas/mips/mips16-branch-unextended.l: New stderr
	output.
	* testsuite/gas/mips/mips.exp: Run the new tests.

8 files changed, 50 insertions, 3 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 742da3e..8a41fc7 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,18 @@
 2016-12-14  Maciej W. Rozycki  <macro@imgtec.com>
 
+	* config/tc-mips.c (md_convert_frag): Report an error instead of
+	asserting on `ext'.
+	* testsuite/gas/mips/mips16-branch-unextended-1.d: New test.
+	* testsuite/gas/mips/mips16-branch-unextended-2.d: New test.
+	* testsuite/gas/mips/mips16-branch-unextended-1.s: New test
+	source.
+	* testsuite/gas/mips/mips16-branch-unextended-2.s: New test.
+	* testsuite/gas/mips/mips16-branch-unextended.l: New stderr
+	output.
+	* testsuite/gas/mips/mips.exp: Run the new tests.
+
+2016-12-14  Maciej W. Rozycki  <macro@imgtec.com>
+
 	* testsuite/gas/mips/mips16-sprel-swap.d: New test.
 	* testsuite/gas/mips/mips16-sprel-swap.s: New test source.
 	* testsuite/gas/mips/mips.exp: Run the new test.
diff --git a/gas/config/tc-mips.c b/gas/config/tc-mips.c
index 4288d96..1241b9c 100644
--- a/gas/config/tc-mips.c
+++ b/gas/config/tc-mips.c
@@ -18369,10 +18369,10 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec, fragS *fragp)
 			    _("unsupported relocation"));
 	      break;
 	    }
-	  if (reloc != BFD_RELOC_NONE)
+	  if (reloc == BFD_RELOC_NONE)
+	    ;
+	  else if (ext)
 	    {
-	      gas_assert (ext);
-
 	      exp.X_op = O_symbol;
 	      exp.X_add_symbol = fragp->fr_symbol;
 	      exp.X_add_number = fragp->fr_offset;
@@ -18387,6 +18387,9 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec, fragS *fragp)
 		 in 2 octets.  */
 	      fixp->fx_no_overflow = 1;
 	    }
+	  else
+	    as_bad_where (fragp->fr_file, fragp->fr_line,
+			  _("invalid unextended operand value"));
 	}
       else
 	mips16_immed (fragp->fr_file, fragp->fr_line, type,
diff --git a/gas/testsuite/gas/mips/mips.exp b/gas/testsuite/gas/mips/mips.exp
index da8d569..d3809e7 100644
--- a/gas/testsuite/gas/mips/mips.exp
+++ b/gas/testsuite/gas/mips/mips.exp
@@ -1298,6 +1298,9 @@ if { [istarget mips*-*-vxworks*] } {
     run_dump_test "mips16-extend"
     run_dump_test "mips16-sprel-swap"
 
+    run_dump_test "mips16-branch-unextended-1"
+    run_dump_test "mips16-branch-unextended-2"
+
     run_dump_test "vxworks1"
     run_dump_test "vxworks1-xgot"
     run_dump_test "vxworks1-el"
diff --git a/gas/testsuite/gas/mips/mips16-branch-unextended-1.d b/gas/testsuite/gas/mips/mips16-branch-unextended-1.d
new file mode 100644
index 0000000..9bccd02
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-branch-unextended-1.d
@@ -0,0 +1,3 @@
+#name: MIPS16 unextended branch instructions with relocation 1
+#as: -32
+#error-output: mips16-branch-unextended.l
diff --git a/gas/testsuite/gas/mips/mips16-branch-unextended-1.s b/gas/testsuite/gas/mips/mips16-branch-unextended-1.s
new file mode 100644
index 0000000..3e59588
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-branch-unextended-1.s
@@ -0,0 +1,8 @@
+	.set	mips16
+	.set	noautoextend
+foo:
+	beqz	$2, baz
+	bnez	$3, baz
+	bteqz	baz
+	btnez	baz
+	b	baz
diff --git a/gas/testsuite/gas/mips/mips16-branch-unextended-2.d b/gas/testsuite/gas/mips/mips16-branch-unextended-2.d
new file mode 100644
index 0000000..b64ee5a
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-branch-unextended-2.d
@@ -0,0 +1,3 @@
+#name: MIPS16 unextended branch instructions with relocation 2
+#as: -32
+#error-output: mips16-branch-unextended.l
diff --git a/gas/testsuite/gas/mips/mips16-branch-unextended-2.s b/gas/testsuite/gas/mips/mips16-branch-unextended-2.s
new file mode 100644
index 0000000..1bc4282
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-branch-unextended-2.s
@@ -0,0 +1,8 @@
+	.set	mips16
+	.set	autoextend
+foo:
+	beqz.t	$2, baz
+	bnez.t	$3, baz
+	bteqz.t	baz
+	btnez.t	baz
+	b.t	baz
diff --git a/gas/testsuite/gas/mips/mips16-branch-unextended.l b/gas/testsuite/gas/mips/mips16-branch-unextended.l
new file mode 100644
index 0000000..611901c
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-branch-unextended.l
@@ -0,0 +1,6 @@
+.*: Assembler messages:
+.*:4: Error: invalid unextended operand value
+.*:5: Error: invalid unextended operand value
+.*:6: Error: invalid unextended operand value
+.*:7: Error: invalid unextended operand value
+.*:8: Error: invalid unextended operand value