[MIPS] Add generation of PLT entries with compact jumps for MIPS R6

Add a new option to get the linker to emit PLTs that use compact
branches instead of delay slot branches.

bfd/
	* elfxx-mips.c (LA25_BC): New macro.
	(mips_elf_link_hash_table)<compact_branches>: New field.
	(STUB_JALRC): New macro.
	(mipsr6_o32_exec_plt0_entry_compact): New array.
	(mipsr6_n32_exec_plt0_entry_compact): Likewise.
	(mipsr6_n64_exec_plt0_entry_compact): Likewise.
	(mipsr6_exec_plt_entry_compact): Likewise.
	(mips_elf_create_la25_stub): Use BC instead of J for stubs
	when compact_branches is true.
	(_bfd_mips_elf_finish_dynamic_symbol): Choose the compact
	PLT for MIPSR6 with compact_branches.  Do not reorder the
	compact branches PLT.  Switch the lazy stub for MIPSR6
	with compact_branches to use JALRC.
	(mips_finish_exec_plt): Choose the compact PLT0 for MIPSR6
	when compact_branches is true.
	(_bfd_mips_elf_compact_branches): New function.
	* elfxx-mips.h (_bfd_mips_elf_compact_branches): New prototype.

ld/
	* emultempl/mipself.em (compact_branches): New static variable.
	(mips_create_output_section_statements): Call
	_bfd_mips_elf_compact_branches.
	(PARSE_AND_LIST_PROLOGUE): Add OPTION_COMPACT_BRANCHES and
	OPTION_NO_COMPACT_BRANCHES.
	(PARSE_AND_LIST_LONGOPTS): Add compact-branches,
	no-compact-branches.
	(PARSE_AND_LIST_OPTIONS): Add --compact-branches,
	--no-compact-branches.
	(PARSE_AND_LIST_ARGS_CASES): Handle the above.
	* ld.texinfo: Document --compact-branches, --no-compact-branches.
	* testsuite/ld-mips-elf/pic-and-nonpic-1-r6.dd: New test.
	* testsuite/ld-mips-elf/pic-and-nonpic-1-r6.nd: New test.
	* testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.dd: New test.
	* testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.gd: New test.
	* testsuite/ld-mips-elf/pic-and-nonpic-1a-r6.s: New test source.
	* testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.s: New test source.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.

1 files changed, 13 insertions, 0 deletions

diff --git a/ld/testsuite/ld-mips-elf/mips-elf.exp b/ld/testsuite/ld-mips-elf/mips-elf.exp
index e2063e5..cbbd9ad 100644
--- a/ld/testsuite/ld-mips-elf/mips-elf.exp
+++ b/ld/testsuite/ld-mips-elf/mips-elf.exp
@@ -523,6 +523,12 @@ if { $linux_gnu } {
 	 {{objdump -dr pic-and-nonpic-1.dd}
 	  {readelf --symbols pic-and-nonpic-1.nd}}
 	 "pic-and-nonpic-1-static1.o"}
+	{"PIC and non-PIC test 1 R6 compact branches (static 1)"
+	 "-melf32btsmip -Tpic-and-nonpic-1.ld --compact-branches" ""
+	 "-32 -EB -mips32r6" {pic-and-nonpic-1a-r6.s pic-and-nonpic-1b.s}
+	 {{objdump -dr pic-and-nonpic-1-r6.dd}
+	  {readelf --symbols pic-and-nonpic-1-r6.nd}}
+	 "pic-and-nonpic-1-r6-static1.o"}
 	{"PIC and non-PIC test 1 (static 2)"
 	 "-melf32btsmip -Tpic-and-nonpic-1.ld tmpdir/pic-and-nonpic-1-rel.o" ""
 	 "" {}
@@ -586,6 +592,13 @@ if { $linux_gnu } {
 	  {readelf --symbols pic-and-nonpic-3b.nd}
 	  {readelf -d pic-and-nonpic-3b.ad}}
 	 "pic-and-nonpic-3b"}
+	{"PIC and non-PIC test 3 R6 compact branches (shared library)"
+	 "-melf32btsmip -shared --compact-branches -Tpic-and-nonpic-3a.ld" ""
+	 "-32 -EB -mips32r6" {pic-and-nonpic-3a-r6.s}
+	 {{readelf --segments pic-and-nonpic-3a.sd}
+	  {readelf -A pic-and-nonpic-3a-r6.gd}
+	  {objdump -dr pic-and-nonpic-3a-r6.dd}}
+	 "pic-and-nonpic-3a-r6.so"}
     }
     run_dump_test_o32 "pic-and-nonpic-3-error" {noarch {as -EB} {ld -EB}}
     run_ld_link_tests {