[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.

8 files changed, 183 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 {
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.dd b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.dd
new file mode 100644
index 0000000..86ad7a9
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.dd
@@ -0,0 +1,50 @@
+
+.*
+
+Disassembly of section \.text:
+
+00041000 <\.pic\.f3>:
+   41000:	3c190004 	lui	t9,0x4
+   41004:	27391060 	addiu	t9,t9,4192
+   41008:	c8000015 	bc	41060 <f3>
+   4100c:	00000000 	nop
+
+00041010 <\.pic\.f2>:
+   41010:	3c190004 	lui	t9,0x4
+   41014:	2739104c 	addiu	t9,t9,4172
+   41018:	c800000c 	bc	4104c <f2>
+	\.\.\.
+
+00041028 <\.pic\.f1>:
+   41028:	3c190004 	lui	t9,0x4
+   4102c:	27391030 	addiu	t9,t9,4144
+
+00041030 <f1>:
+   41030:	3c1c0002 	lui	gp,0x2
+   41034:	279c6fd0 	addiu	gp,gp,28624
+   41038:	0399e021 	addu	gp,gp,t9
+   4103c:	0c010418 	jal	41060 <f3>
+   41040:	00000000 	nop
+   41044:	03e00009 	jr	ra
+   41048:	00000000 	nop
+
+0004104c <f2>:
+   4104c:	3c1c0002 	lui	gp,0x2
+   41050:	279c6fb4 	addiu	gp,gp,28596
+   41054:	0399e021 	addu	gp,gp,t9
+   41058:	03e00009 	jr	ra
+   4105c:	00000000 	nop
+
+00041060 <f3>:
+   41060:	00021400 	sll	v0,v0,0x10
+   41064:	00431021 	addu	v0,v0,v1
+	\.\.\.
+
+00041070 <__start>:
+   41070:	0c01040a 	jal	41028 <\.pic\.f1>
+   41074:	00000000 	nop
+   41078:	0c010404 	jal	41010 <\.pic\.f2>
+   4107c:	00000000 	nop
+   41080:	0c010400 	jal	41000 <\.pic\.f3>
+   41084:	00000000 	nop
+	\.\.\.
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.nd b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.nd
new file mode 100644
index 0000000..5264505
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.nd
@@ -0,0 +1,9 @@
+#...
+.*: 00041000 +16 +FUNC +LOCAL +DEFAULT .* \.pic\.f3
+.*: 00068000 +0 +NOTYPE +LOCAL +DEFAULT +ABS _gp
+.*: 00041028 +8 +FUNC +LOCAL +DEFAULT .* \.pic\.f1
+.*: 00041010 +16 +FUNC +LOCAL +DEFAULT .* \.pic\.f2
+.*: 00041060 +8 +FUNC  +GLOBAL +DEFAULT .* f3
+.*: 00041070 +24 +FUNC +GLOBAL +DEFAULT .* __start
+.*: 0004104c +20 +FUNC +GLOBAL +DEFAULT .* f2
+.*: 00041030 +28 +FUNC +GLOBAL +DEFAULT .* f1
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.s b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.s
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1-r6.s
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-1a-r6.s b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1a-r6.s
new file mode 100644
index 0000000..340004b
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-1a-r6.s
@@ -0,0 +1,28 @@
+	.abicalls
+	.global	f1
+	.global	f2
+	.global	f3
+	.ent	f1
+f1:
+	.set	noreorder
+	.cpload	$25
+	.set	reorder
+	.option	pic0
+	jal	f3
+	.option	pic2
+	jr	$31
+	.end	f1
+
+	.ent	f2
+f2:
+	.set	noreorder
+	.cpload	$25
+	.set	reorder
+	jr	$31
+	.end	f2
+
+	.ent	f3
+f3:
+	sll	$2,16
+	addu	$2,$2,$3
+	.end	f3
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.dd b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.dd
new file mode 100644
index 0000000..80dac37
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.dd
@@ -0,0 +1,36 @@
+# GOT layout:
+#
+# -32752: lazy resolution function
+# -32748: reserved for module pointer
+# -32744: the GOT page entry
+# -32740: foo's GOT entry
+# -32736: ext's GOT entry
+
+.*
+
+Disassembly of section \.text:
+
+00000800 <foo>:
+ 800:	3c1c0001 	lui	gp,0x1
+ 804:	279c7bf0 	addiu	gp,gp,31728
+ 808:	0399e021 	addu	gp,gp,t9
+ 80c:	8f99801c 	lw	t9,-32740\(gp\)
+ 810:	8f828018 	lw	v0,-32744\(gp\)
+ 814:	24420000 	addiu	v0,v0,0
+ 818:	d8190000 	jrc	t9
+
+0000081c <bar>:
+ 81c:	3c1c0001 	lui	gp,0x1
+ 820:	279c7bd4 	addiu	gp,gp,31700
+ 824:	0399e021 	addu	gp,gp,t9
+ 828:	8f998020 	lw	t9,-32736\(gp\)
+ 82c:	d8190000 	jrc	t9
+#...
+Disassembly of section \.MIPS\.stubs:
+
+00000c00 <_MIPS_STUBS_>:
+ c00:	8f998010 	lw	t9,-32752\(gp\)
+ c04:	03e07825 	move	t7,ra
+ c08:	2418[0-9a-f]+ 	li	t8,[0-9]+
+ c0c:	f8190000 	jalrc	t9
+	\.\.\.
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.gd b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.gd
new file mode 100644
index 0000000..af046ee
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.gd
@@ -0,0 +1,21 @@
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_MIPS_ABI_FP: Hard float \(32-bit CPU, 64-bit FPU\)
+
+Primary GOT:
+ Canonical gp value: 000183f0
+
+ Reserved entries:
+   Address     Access  Initial Purpose
+  00010400 -32752\(gp\) 00000000 Lazy resolver
+  00010404 -32748\(gp\) 80000000 Module pointer \(GNU extension\)
+
+ Local entries:
+   Address     Access  Initial
+  00010408 -32744\(gp\) 00010000
+
+ Global entries:
+   Address     Access  Initial Sym\.Val\. Type    Ndx Name
+  0001040c -32740\(gp\) 00000800 00000800 FUNC      6 foo
+  00010410 -32736\(gp\) 00000c00 00000c00 FUNC    UND ext
diff --git a/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.s b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.s
new file mode 100644
index 0000000..fb8eb81
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/pic-and-nonpic-3a-r6.s
@@ -0,0 +1,26 @@
+	.abicalls
+	.set	nomips16
+	.global	foo
+	.ent	foo
+foo:
+	.set noreorder
+	.cpload	$25
+	.set reorder
+	lw	$25,%call16(foo)($28)
+	lw	$2,%got(data)($28)
+	addiu	$2,$2,%lo(data)
+	jrc	$25
+	.end	foo
+
+	.global	bar
+	.ent	bar
+bar:
+	.set noreorder
+	.cpload	$25
+	.set reorder
+	lw	$25,%call16(ext)($28)
+	jrc	$25
+	.end	bar
+
+	.data
+data:	.word	0x12345678