MIPS16/GAS: Disallow EXTEND delay-slot scheduling

Do not allow any explicitly coded EXTEND instruction to be automatically
scheduled into a jump delay slot, as an EXTEND prefix is coupled with
the next regular MIPS16 instruction and therefore swapping it with a
jump would change program's semantics; EXTEND is not architecturally
allowed to be present in a jump delay slot anyway.

	opcodes/
	* mips16-opc.c (mips16_opcodes): Set NODS in `pinfo' for
	"extend".

	gas/
	* testsuite/gas/mips/mips16-extend-swap.d: New test.
	* testsuite/gas/mips/mips16-extend-swap.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new test.

6 files changed, 56 insertions, 1 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index d78c57d..53fa952 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,9 @@
+2016-12-23  Maciej W. Rozycki  <macro@imgtec.com>
+
+	* testsuite/gas/mips/mips16-extend-swap.d: New test.
+	* testsuite/gas/mips/mips16-extend-swap.s: New test source.
+	* testsuite/gas/mips/mips.exp: Run the new test.
+
 2016-12-23  Joe Seymour  <joe.s@somniumtech.com>
 
 	* config/tc-msp430.c (msp430_mcu_data): Sync with data from TI's
diff --git a/gas/testsuite/gas/mips/mips.exp b/gas/testsuite/gas/mips/mips.exp
index cd62e44..c16891a 100644
--- a/gas/testsuite/gas/mips/mips.exp
+++ b/gas/testsuite/gas/mips/mips.exp
@@ -1341,6 +1341,7 @@ if { [istarget mips*-*-vxworks*] } {
     run_list_test "mips16e-save-err" "-march=mips32 -32"
     run_dump_test "mips16-intermix"
     run_dump_test "mips16-extend"
+    run_dump_test "mips16-extend-swap"
     run_dump_test "mips16-sprel-swap"
     run_dump_test "mips16-sdrasp"
 
diff --git a/gas/testsuite/gas/mips/mips16-extend-swap.d b/gas/testsuite/gas/mips/mips16-extend-swap.d
new file mode 100644
index 0000000..eb9dd73
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-extend-swap.d
@@ -0,0 +1,22 @@
+#objdump: -d --prefix-addresses --show-raw-insn
+#name: MIPS16 jump delay slot scheduling for EXTEND instructions
+#as: -32
+
+# Verify that EXTEND instructions are not scheduled into a jump delay slot.
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> f123      	extend	0x123
+[0-9a-f]+ <[^>]*> 1800 0000 	jal	00000000 <foo>
+[0-9a-f]+ <[^>]*> 6500      	nop
+[0-9a-f]+ <[^>]*> f123      	extend	0x123
+[0-9a-f]+ <[^>]*> 1c00 0000 	jalx	00000000 <foo>
+[0-9a-f]+ <[^>]*> 6500      	nop
+[0-9a-f]+ <[^>]*> f123 eb00 	jr	v1
+[0-9a-f]+ <[^>]*> 6500      	nop
+[0-9a-f]+ <[^>]*> f123 e820 	jr	ra
+[0-9a-f]+ <[^>]*> 6500      	nop
+[0-9a-f]+ <[^>]*> f123 eb40 	jalr	v1
+[0-9a-f]+ <[^>]*> 6500      	nop
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/mips16-extend-swap.s b/gas/testsuite/gas/mips/mips16-extend-swap.s
new file mode 100644
index 0000000..c299cf1
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips16-extend-swap.s
@@ -0,0 +1,21 @@
+	.set	mips1
+	.set	mips16
+foo:
+	extend	0x123
+	jal	bar
+
+	extend	0x123
+	jalx	baz
+
+	extend	0x123
+	jr	$3
+
+	extend	0x123
+	jr	$31
+
+	extend	0x123
+	jalr	$3
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align	4, 0
+	.space	16
diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index 9938992..5166be4 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,5 +1,10 @@
 2016-12-23  Maciej W. Rozycki  <macro@imgtec.com>
 
+	* mips16-opc.c (mips16_opcodes): Set NODS in `pinfo' for
+	"extend".
+
+2016-12-23  Maciej W. Rozycki  <macro@imgtec.com>
+
 	* mips-dis.c (set_default_mips_dis_options): Use
 	HAVE_BFD_MIPS_ELF_GET_ABIFLAGS rather than BFD64 to guard the
 	call to `bfd_mips_elf_get_abiflags'.
diff --git a/opcodes/mips16-opc.c b/opcodes/mips16-opc.c
index 758b78f..7d430dd 100644
--- a/opcodes/mips16-opc.c
+++ b/opcodes/mips16-opc.c
@@ -357,7 +357,7 @@ const struct mips_opcode mips16_opcodes[] =
 {"zew",	    "x",	0xe851, 0xf8ff,		MOD_1,			0,		I64,	0,	0 },
   /* Place EXTEND last so that it catches any prefix that didn't match
      anything.  */
-{"extend",  "e",	0xf000, 0xf800,		0,			0,		I1,	0,	0 },
+{"extend",  "e",	0xf000, 0xf800,		NODS,			0,		I1,	0,	0 },
 };
 
 const int bfd_mips16_num_opcodes =