[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.

11 files changed, 236 insertions, 2 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 05af393..6896a72 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,25 @@
+2019-05-21  Matthew Fortune  <matthew.fortune@mips.com>
+	    Faraz Shahbazker  <fshahbazker@wavecomp.com>
+
+	* 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.
+
 2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>
 
 	* testsuite/ld-arm/arm-elf.exp: Add tests
diff --git a/ld/emultempl/mipself.em b/ld/emultempl/mipself.em
index d9eeef3..ec908d7 100644
--- a/ld/emultempl/mipself.em
+++ b/ld/emultempl/mipself.em
@@ -44,6 +44,7 @@ static bfd *stub_bfd;
 
 static bfd_boolean insn32;
 static bfd_boolean ignore_branch_isa;
+static bfd_boolean compact_branches;
 
 static void
 mips_after_parse (void)
@@ -216,7 +217,10 @@ mips_create_output_section_statements (void)
 				${gnu_target});
 
   if (is_mips_elf (link_info.output_bfd))
-    _bfd_mips_elf_init_stubs (&link_info, mips_add_stub_section);
+    {
+      _bfd_mips_elf_compact_branches (&link_info, compact_branches);
+      _bfd_mips_elf_init_stubs (&link_info, mips_add_stub_section);
+    }
 }
 
 /* This is called after we have merged the private data of the input bfds.  */
@@ -269,7 +273,9 @@ enum
     OPTION_INSN32 = 301,
     OPTION_NO_INSN32,
     OPTION_IGNORE_BRANCH_ISA,
-    OPTION_NO_IGNORE_BRANCH_ISA
+    OPTION_NO_IGNORE_BRANCH_ISA,
+    OPTION_COMPACT_BRANCHES,
+    OPTION_NO_COMPACT_BRANCHES
   };
 '
 
@@ -278,6 +284,8 @@ PARSE_AND_LIST_LONGOPTS='
   { "no-insn32", no_argument, NULL, OPTION_NO_INSN32 },
   { "ignore-branch-isa", no_argument, NULL, OPTION_IGNORE_BRANCH_ISA },
   { "no-ignore-branch-isa", no_argument, NULL, OPTION_NO_IGNORE_BRANCH_ISA },
+  { "compact-branches", no_argument, NULL, OPTION_COMPACT_BRANCHES },
+  { "no-compact-branches", no_argument, NULL, OPTION_NO_COMPACT_BRANCHES },
 '
 
 PARSE_AND_LIST_OPTIONS='
@@ -295,6 +303,12 @@ PARSE_AND_LIST_OPTIONS='
   --no-ignore-branch-isa      Reject invalid branch relocations requiring\n\
                               an ISA mode switch\n"
 		   ));
+  fprintf (file, _("\
+  --compact-branches          Generate compact branches/jumps for MIPS R6\n"
+		   ));
+  fprintf (file, _("\
+  --no-compact-branches       Generate delay slot branches/jumps for MIPS R6\n"
+		   ));
 '
 
 PARSE_AND_LIST_ARGS_CASES='
@@ -313,6 +327,14 @@ PARSE_AND_LIST_ARGS_CASES='
     case OPTION_NO_IGNORE_BRANCH_ISA:
       ignore_branch_isa = FALSE;
       break;
+
+    case OPTION_COMPACT_BRANCHES:
+      compact_branches = TRUE;
+      break;
+
+    case OPTION_NO_COMPACT_BRANCHES:
+      compact_branches = FALSE;
+      break;
 '
 
 LDEMUL_AFTER_PARSE=mips_after_parse
diff --git a/ld/ld.texi b/ld/ld.texi
index f47db75..671a2a5 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -3197,6 +3197,13 @@ calculated.  By default or if @samp{--no-ignore-branch-isa} is used
 a check is made causing the loss of an ISA mode transition to produce
 an error.
 
+@kindex --compact-branches
+@item --compact-branches
+@kindex --no-compact-branches
+@item --compact-branches
+These options control the generation of compact instructions by the linker
+in the PLT entries for MIPS R6.
+
 @end table
 
 @c man end
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