MIPS: Add options to control branch ISA checks

Complement commit 9d862524f6ae ("MIPS: Verify the ISA mode and alignment
of branch and jump targets") and add GAS and LD options to control the
checks for invalid branches between ISA modes introduced there, to help
with some handwritten code lacking `.insn' annotation for labels used as
branch targets and code produced by older versions of GCC which suffers
from the issue with branches to code that has been optimized away,
addressed with GCC commit 242424 ("MIPS/GCC: Mark trailing labels with
`.insn'"), <https://gcc.gnu.org/ml/gcc-patches/2016-11/msg01061.html>.

	bfd/
	* elfxx-mips.h (_bfd_mips_elf_insn32): Rename prototype to...
	(_bfd_mips_elf_linker_flags): ... this.  Add another parameter.
	* elfxx-mips.c (mips_elf_link_hash_table): Add
	`ignore_branch_isa' member.
	(mips_elf_perform_relocation): Do not treat an ISA mode mismatch
	in branch relocation calculation as an error if
	`ignore_branch_isa' has been set.
	(_bfd_mips_elf_insn32): Rename to...
	(_bfd_mips_elf_linker_flags): ... this.  Rename the `on'
	parameter to `insn32' and add an `ignore_branch_isa' parameter.
	Handle the new parameter.

	gas/
	* config/tc-mips.c (mips_ignore_branch_isa): New variable.
	(options): Add OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA enum values.
	(md_longopts): Add "mignore-branch-isa" and
	"mno-ignore-branch-isa" options.
	(md_parse_option): Handle OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA.
	(fix_bad_cross_mode_branch_p): Return FALSE if
	`mips_ignore_branch_isa' has been set.
	(md_show_usage): Add `-mignore-branch-isa' and
	`-mno-ignore-branch-isa'.

	* doc/as.texinfo (Target MIPS options): Add
	`-mignore-branch-isa' and `-mno-ignore-branch-isa' options.
	(-mignore-branch-isa, -mno-ignore-branch-isa): New options.
	* doc/c-mips.texi (MIPS Options): Add `-mignore-branch-isa' and
	`-mno-ignore-branch-isa' options.

	* testsuite/gas/mips/branch-local-ignore-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-3.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n32-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n32-3.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n64-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n64-3.d: New test.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* emultempl/mipself.em (ignore_branch_isa): New variable.
	(mips_create_output_section_statements): Rename
	`_bfd_mips_elf_insn32' called to `_bfd_mips_elf_linker_flags',
	add `ignore_branch_isa' argument.
	(PARSE_AND_LIST_PROLOGUE): Add OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA enum values.
	(PARSE_AND_LIST_LONGOPTS): Add "ignore-branch-isa" and
	"no-ignore-branch-isa" options.
	(PARSE_AND_LIST_OPTIONS): Add `--ignore-branch-isa' and
	`--no-ignore-branch-isa'.
	(PARSE_AND_LIST_ARGS_CASES): Handle OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA.

	* ld.texinfo (Options specific to MIPS targets): Add
	`--ignore-branch-isa' and `--no-ignore-branch-isa' options.
	(ld and the MIPS family): Likewise.

	* testsuite/ld-mips-elf/bal-jalx-pic-ignore.d: New test.
	* testsuite/ld-mips-elf/bal-jalx-pic-ignore-n32.d: New test.
	* testsuite/ld-mips-elf/bal-jalx-pic-ignore-n64.d: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-2.d: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-r6-1: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-mips16: New
	test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-micromips: New
	test.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.

7 files changed, 174 insertions, 0 deletions

diff --git a/gas/testsuite/gas/mips/branch-local-ignore-2.d b/gas/testsuite/gas/mips/branch-local-ignore-2.d
new file mode 100644
index 0000000..ddac741
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-2.d
@@ -0,0 +1,29 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS branch local symbol relocation 2 (ignore branch ISA)
+#as: -32 -mignore-branch-isa
+#source: branch-local-2.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 1000ffff 	b	00001014 <bar\+0x4>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 1443ffff 	bne	v0,v1,0000101c <bar\+0xc>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 0451ffff 	bgezal	v0,00001024 <bar\+0x14>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 0450ffff 	bltzal	v0,0000102c <bar\+0x1c>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jalr	zero,ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/branch-local-ignore-3.d b/gas/testsuite/gas/mips/branch-local-ignore-3.d
new file mode 100644
index 0000000..918a2ce
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-3.d
@@ -0,0 +1,23 @@
+#objdump: -dr --prefix-addresses --show-raw-insn -mmips:isa32r6
+#name: MIPS branch local symbol relocation 3 (ignore branch ISA)
+#as: -32 -mignore-branch-isa
+#source: branch-local-3.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> cbffffff 	bc	00001014 <bar\+0x4>
+[ 	]*[0-9a-f]+: R_MIPS_PC26_S2	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> d85fffff 	beqzc	v0,0000101c <bar\+0xc>
+[ 	]*[0-9a-f]+: R_MIPS_PC21_S2	foo
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jr	ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/branch-local-ignore-n32-2.d b/gas/testsuite/gas/mips/branch-local-ignore-n32-2.d
new file mode 100644
index 0000000..080402c
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-n32-2.d
@@ -0,0 +1,29 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS branch local symbol relocation 2 (ignore branch ISA, n32)
+#as: -n32 -march=from-abi -mignore-branch-isa
+#source: branch-local-2.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 10000000 	b	00001018 <bar\+0x8>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 14430000 	bne	v0,v1,00001020 <bar\+0x10>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 04510000 	bgezal	v0,00001028 <bar\+0x18>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 04500000 	bltzal	v0,00001030 <bar\+0x20>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jalr	zero,ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/branch-local-ignore-n32-3.d b/gas/testsuite/gas/mips/branch-local-ignore-n32-3.d
new file mode 100644
index 0000000..a4dbc7f
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-n32-3.d
@@ -0,0 +1,23 @@
+#objdump: -dr --prefix-addresses --show-raw-insn -mmips:isa32r6
+#name: MIPS branch local symbol relocation 3 (ignore branch ISA, n32)
+#as: -n32 -march=from-abi -mignore-branch-isa
+#source: branch-local-3.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> c8000000 	bc	00001018 <bar\+0x8>
+[ 	]*[0-9a-f]+: R_MIPS_PC26_S2	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> d8400000 	beqzc	v0,00001020 <bar\+0x10>
+[ 	]*[0-9a-f]+: R_MIPS_PC21_S2	foo-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jr	ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/branch-local-ignore-n64-2.d b/gas/testsuite/gas/mips/branch-local-ignore-n64-2.d
new file mode 100644
index 0000000..12cd510
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-n64-2.d
@@ -0,0 +1,37 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS branch local symbol relocation 2 (ignore branch ISA, n64)
+#as: -64 -march=from-abi -mignore-branch-isa
+#source: branch-local-2.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 10000000 	b	0000000000001018 <bar\+0x8>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 14430000 	bne	v0,v1,0000000000001020 <bar\+0x10>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 04510000 	bgezal	v0,0000000000001028 <bar\+0x18>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 04500000 	bltzal	v0,0000000000001030 <bar\+0x20>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jalr	zero,ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/branch-local-ignore-n64-3.d b/gas/testsuite/gas/mips/branch-local-ignore-n64-3.d
new file mode 100644
index 0000000..9d6dca9
--- /dev/null
+++ b/gas/testsuite/gas/mips/branch-local-ignore-n64-3.d
@@ -0,0 +1,27 @@
+#objdump: -dr --prefix-addresses --show-raw-insn -mmips:isa32r6
+#name: MIPS branch local symbol relocation 3 (ignore branch ISA, n64)
+#as: -64 -march=from-abi -mignore-branch-isa
+#source: branch-local-3.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> c8000000 	bc	0000000000001018 <bar\+0x8>
+[ 	]*[0-9a-f]+: R_MIPS_PC26_S2	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> d8400000 	beqzc	v0,0000000000001020 <bar\+0x10>
+[ 	]*[0-9a-f]+: R_MIPS_PC21_S2	foo-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[ 	]*[0-9a-f]+: R_MIPS_NONE	\*ABS\*-0x4
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jr	ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/mips.exp b/gas/testsuite/gas/mips/mips.exp
index 4580fbf..5a69542 100644
--- a/gas/testsuite/gas/mips/mips.exp
+++ b/gas/testsuite/gas/mips/mips.exp
@@ -626,16 +626,22 @@ if { [istarget mips*-*-vxworks*] } {
     run_dump_test "branch-weak-7"
     run_dump_test "branch-local-1"
     run_dump_test "branch-local-2"
+    run_dump_test "branch-local-ignore-2"
     run_dump_test "branch-local-3"
+    run_dump_test "branch-local-ignore-3"
     run_dump_test "branch-local-4"
     if $has_newabi {
 	run_dump_test "branch-local-n32-1"
 	run_dump_test "branch-local-n32-2"
+	run_dump_test "branch-local-ignore-n32-2"
 	run_dump_test "branch-local-n32-3"
+	run_dump_test "branch-local-ignore-n32-3"
 	run_dump_test "branch-local-n32-4"
 	run_dump_test "branch-local-n64-1"
 	run_dump_test "branch-local-n64-2"
+	run_dump_test "branch-local-ignore-n64-2"
 	run_dump_test "branch-local-n64-3"
+	run_dump_test "branch-local-ignore-n64-3"
 	run_dump_test "branch-local-n64-4"
     }
     run_dump_test "branch-addend"