MIPS/opcodes: Fix alias annotation for branch instructions

Correct issues with INSN2_ALIAS annotation for branch instructions:

- regular MIPS BEQZ/L and BNEZ/L assembly instructions are idioms for
  BEQ/L and BNE/L respectively with the `rs' operand equal to $0,

- microMIPS 32-bit BEQZ and BNEZ assembly instructions are idioms for
  BEQ and BNE respectively with the `rt' operand equal to $0,

- regular MIPS BAL assembly instruction is an idiom for architecture
  levels of up to the MIPSr5 ISA and a machine instruction on its own
  from the MIPSr6 ISA up.

Add missing annotation to BEQZ/L and BNEZ/L accordingly then and add a
new entry for BAL for the MIPSr6 ISA, correcting a disassembly bug:

$ mips-linux-gnu-objdump -m mips:isa64r6 -M no-aliases -d bal.o

bal.o:     file format elf32-tradlittlemips

Disassembly of section .text:

00000000 <foo>:
   0:	04110000 	0x4110000
	...
$

Add test cases accordingly.

Parts for regular MIPS BEQZ/L and BNEZ/L instructions from Sagar Patel.

2022-03-06  Maciej W. Rozycki  <macro@orcam.me.uk>

	binutils/
	* testsuite/binutils-all/mips/mips1-branch-alias.d: New test.
	* testsuite/binutils-all/mips/mips1-branch-noalias.d: New test.
	* testsuite/binutils-all/mips/mips2-branch-alias.d: New test.
	* testsuite/binutils-all/mips/mips2-branch-noalias.d: New test.
	* testsuite/binutils-all/mips/mips32r6-branch-alias.d: New test.
	* testsuite/binutils-all/mips/mips32r6-branch-noalias.d: New
	test.
	* testsuite/binutils-all/mips/micromips-branch-alias.d: New
	test.
	* testsuite/binutils-all/mips/micromips-branch-noalias.d: New
	test.
	* testsuite/binutils-all/mips/mips-branch-alias.s: New test
	source.
	* testsuite/binutils-all/mips/micromips-branch-alias.s: New test
	source.
	* testsuite/binutils-all/mips/mips.exp: Run the new tests.

2022-03-06  Sagar Patel  <sagarmp@cs.unc.edu>
	    Maciej W. Rozycki  <macro@orcam.me.uk>

	opcodes/
	* mips-opc.c (mips_builtin_opcodes): Fix INSN2_ALIAS annotation
	for "bal", "beqz", "beqzl", "bnez" and "bnezl" instructions.
	* micromips-opc.c (micromips_opcodes): Likewise for "beqz" and
	"bnez" instructions.

11 files changed, 181 insertions, 0 deletions

diff --git a/binutils/testsuite/binutils-all/mips/micromips-branch-alias.d b/binutils/testsuite/binutils-all/mips/micromips-branch-alias.d
new file mode 100644
index 0000000..3a5a879
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/micromips-branch-alias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -d --prefix-addresses --show-raw-insn
+#name: microMIPS branch instruction alias disassembly
+#source: micromips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 9400 0000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4040 0000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 40e0 0000 	bc	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 9401 0000 	beqz	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> b401 0000 	bnez	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4060 0000 	bal	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4260 0000 	bals	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/micromips-branch-alias.s b/binutils/testsuite/binutils-all/mips/micromips-branch-alias.s
new file mode 100644
index 0000000..3d27bb4
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/micromips-branch-alias.s
@@ -0,0 +1,17 @@
+	.text
+	.set	mips32r3
+	.set	noat
+	.set	noreorder
+	.set	micromips
+foo:
+	beq	$0, $0, . + 4
+	bgez	$0, . + 4
+	beqzc	$0, . + 4
+	beqz	$1, . + 4
+	bnez	$1, . + 4
+	bgezal	$0, . + 4
+	bgezals	$0, . + 4
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align	4, 0
+	.space	16
diff --git a/binutils/testsuite/binutils-all/mips/micromips-branch-noalias.d b/binutils/testsuite/binutils-all/mips/micromips-branch-noalias.d
new file mode 100644
index 0000000..3c9fa7d
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/micromips-branch-noalias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -M no-aliases -d --prefix-addresses --show-raw-insn
+#name: microMIPS branch canonical alias disassembly
+#source: micromips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 9400 0000 	beq	zero,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4040 0000 	bgez	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 40e0 0000 	beqzc	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 9401 0000 	beq	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> b401 0000 	bne	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4060 0000 	bgezal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 4260 0000 	bgezals	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 0000 0000 	sll	zero,zero,0x0
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips-branch-alias.s b/binutils/testsuite/binutils-all/mips/mips-branch-alias.s
new file mode 100644
index 0000000..dfde3c0
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips-branch-alias.s
@@ -0,0 +1,18 @@
+	.text
+	.set	noat
+	.set	noreorder
+	.set	mips2
+foo:
+	beq	$0, $0, . + 4
+	bgez	$0, . + 4
+	bgezal	$0, . + 4
+	bltzal	$0, . + 4
+	beqz	$1, . + 4
+	bnez	$1, . + 4
+
+	beqzl	$1, . + 4
+	bnezl	$1, . + 4
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align	4, 0
+	.space	16
diff --git a/binutils/testsuite/binutils-all/mips/mips.exp b/binutils/testsuite/binutils-all/mips/mips.exp
index 3d818f8..b6fe11d 100644
--- a/binutils/testsuite/binutils-all/mips/mips.exp
+++ b/binutils/testsuite/binutils-all/mips/mips.exp
@@ -238,6 +238,14 @@ run_dump_test_o32 "mips16-extend-insn" noarch
 run_dump_test_o32 "mips16e2-extend-insn" noarch
 run_dump_test_o32 "mips16-alias" noarch
 run_dump_test_o32 "mips16-noalias" noarch
+run_dump_test_o32 "mips1-branch-alias"
+run_dump_test_o32 "mips1-branch-noalias"
+run_dump_test_o32 "mips2-branch-alias"
+run_dump_test_o32 "mips2-branch-noalias"
+run_dump_test_o32 "mips32r6-branch-alias"
+run_dump_test_o32 "mips32r6-branch-noalias"
+run_dump_test_o32 "micromips-branch-alias"
+run_dump_test_o32 "micromips-branch-noalias"
 
 run_dump_test_o32 "mips-note-2"
 run_dump_test_n32 "mips-note-2-n32"
diff --git a/binutils/testsuite/binutils-all/mips/mips1-branch-alias.d b/binutils/testsuite/binutils-all/mips/mips1-branch-alias.d
new file mode 100644
index 0000000..467775f
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips1-branch-alias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -m mips:3000 -d --prefix-addresses --show-raw-insn
+#name: MIPS1 branch instruction alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bal	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	bltzal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 10200000 	beqz	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bnez	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	0x50200000
+[0-9a-f]+ <[^>]*> 54200000 	0x54200000
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips1-branch-noalias.d b/binutils/testsuite/binutils-all/mips/mips1-branch-noalias.d
new file mode 100644
index 0000000..b3fa8a0
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips1-branch-noalias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -M no-aliases -m mips:3000 -d --prefix-addresses --show-raw-insn
+#name: MIPS1 branch canonical alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	beq	zero,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	bgez	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bgezal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	bltzal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 10200000 	beq	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bne	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	0x50200000
+[0-9a-f]+ <[^>]*> 54200000 	0x54200000
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips2-branch-alias.d b/binutils/testsuite/binutils-all/mips/mips2-branch-alias.d
new file mode 100644
index 0000000..f1fbeea
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips2-branch-alias.d
@@ -0,0 +1,18 @@
+#PROG: objcopy
+#objdump: -m mips:6000 -d --prefix-addresses --show-raw-insn
+#name: MIPS2 branch instruction alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bal	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	bltzal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 10200000 	beqz	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bnez	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	beqzl	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 54200000 	bnezl	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips2-branch-noalias.d b/binutils/testsuite/binutils-all/mips/mips2-branch-noalias.d
new file mode 100644
index 0000000..0f819e8
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips2-branch-noalias.d
@@ -0,0 +1,18 @@
+#PROG: objcopy
+#objdump: -M no-aliases -m mips:6000 -d --prefix-addresses --show-raw-insn
+#name: MIPS2 branch canonical alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	beq	zero,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	bgez	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bgezal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	bltzal	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 10200000 	beq	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bne	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	beql	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 54200000 	bnel	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 00000000 	sll	zero,zero,0x0
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips32r6-branch-alias.d b/binutils/testsuite/binutils-all/mips/mips32r6-branch-alias.d
new file mode 100644
index 0000000..aebbb26
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips32r6-branch-alias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -m mips:isa32r6 -d --prefix-addresses --show-raw-insn
+#name: MIPS32r6 branch instruction alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	b	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bal	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	nal
+[0-9a-f]+ <[^>]*> 10200000 	beqz	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bnez	at,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	0x50200000
+[0-9a-f]+ <[^>]*> 54200000 	0x54200000
+	\.\.\.
diff --git a/binutils/testsuite/binutils-all/mips/mips32r6-branch-noalias.d b/binutils/testsuite/binutils-all/mips/mips32r6-branch-noalias.d
new file mode 100644
index 0000000..d7d512f
--- /dev/null
+++ b/binutils/testsuite/binutils-all/mips/mips32r6-branch-noalias.d
@@ -0,0 +1,17 @@
+#PROG: objcopy
+#objdump: -M no-aliases -m mips:isa32r6 -d --prefix-addresses --show-raw-insn
+#name: MIPS32r6 branch canonical alias disassembly
+#source: mips-branch-alias.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 10000000 	beq	zero,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04010000 	bgez	zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04110000 	bal	[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 04100000 	nal
+[0-9a-f]+ <[^>]*> 10200000 	beq	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 14200000 	bne	at,zero,[0-9a-f]+ <[^>]*>
+[0-9a-f]+ <[^>]*> 50200000 	0x50200000
+[0-9a-f]+ <[^>]*> 54200000 	0x54200000
+	\.\.\.