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.

1 files changed, 18 insertions, 0 deletions

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
+	\.\.\.