bfd: aarch64: Optimize BTI stubs PR30076

Don't insert a second stub if the target is already compatible with
an indirect branch.

3 files changed, 207 insertions, 0 deletions

diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 80662de7e44..ec55bf49931 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -463,6 +463,7 @@ run_dump_test "undef-tls"
 
 run_dump_test "bti-far-1"
 run_dump_test "bti-far-2"
+run_dump_test "bti-far-opt"
 
 if { ![skip_sframe_tests] } {
   run_dump_test "sframe-simple-1"
diff --git a/ld/testsuite/ld-aarch64/bti-far-opt.d b/ld/testsuite/ld-aarch64/bti-far-opt.d
new file mode 100644
index 00000000000..ff20d0c2825
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/bti-far-opt.d
@@ -0,0 +1,153 @@
+#name: Check linker stubs with indirect calls handle BTI when target has BTI.
+#source: bti-far-opt.s
+#target: [check_shared_lib_support]
+#as: -mabi=lp64
+#ld: -shared -T bti-far.ld
+#objdump: -dr
+
+[^:]*: *file format elf64-.*aarch64
+
+
+Disassembly of section \.plt:
+
+0000000000018000 <\.plt>:
+   18000:	d503245f 	bti	c
+   18004:	a9bf7bf0 	stp	x16, x30, \[sp, #-16\]!
+   18008:	900000d0 	adrp	x16, 30000 <_GLOBAL_OFFSET_TABLE_>
+   1800c:	f9400e11 	ldr	x17, \[x16, #24\]
+   18010:	91006210 	add	x16, x16, #0x18
+   18014:	d61f0220 	br	x17
+   18018:	d503201f 	nop
+   1801c:	d503201f 	nop
+
+0000000000018020 <foo@plt>:
+   18020:	900000d0 	adrp	x16, 30000 <_GLOBAL_OFFSET_TABLE_>
+   18024:	f9401211 	ldr	x17, \[x16, #32\]
+   18028:	91008210 	add	x16, x16, #0x20
+   1802c:	d61f0220 	br	x17
+   18030:	14000004 	b	18040 <__foo_bti_veneer\+0x8>
+   18034:	d503201f 	nop
+
+0000000000018038 <__foo_bti_veneer>:
+   18038:	d503245f 	bti	c
+   1803c:	17fffff9 	b	18020 <foo@plt>
+
+Disassembly of section \.text:
+
+0000000000020000 <_start>:
+   20000:	97ffe008 	bl	18020 <foo@plt>
+   20004:	9400000f 	bl	20040 <___veneer>
+   20008:	94000001 	bl	2000c <baz>
+
+000000000002000c <baz>:
+   2000c:	d503201f 	nop
+
+0000000000020010 <baz_bti_>:
+   20010:	d503241f 	bti
+
+0000000000020014 <baz_bti_c>:
+   20014:	d503245f 	bti	c
+
+0000000000020018 <baz_bti_j>:
+   20018:	d503249f 	bti	j
+
+000000000002001c <baz_bti_jc>:
+   2001c:	d50324df 	bti	jc
+
+0000000000020020 <baz_paciasp>:
+   20020:	d503233f 	paciasp
+
+0000000000020024 <baz_pacibsp>:
+   20024:	d503237f 	pacibsp
+   20028:	1400000c 	b	20058 <___veneer\+0x18>
+   2002c:	d503201f 	nop
+
+0000000000020030 <___bti_veneer>:
+   20030:	d503245f 	bti	c
+   20034:	17fffff6 	b	2000c <baz>
+
+0000000000020038 <___bti_veneer>:
+   20038:	d503245f 	bti	c
+   2003c:	17fffff5 	b	20010 <baz_bti_>
+
+0000000000020040 <___veneer>:
+   20040:	90091910 	adrp	x16, 12340000 <foo>
+   20044:	9101e210 	add	x16, x16, #0x78
+   20048:	d61f0200 	br	x16
+	\.\.\.
+
+Disassembly of section \.far:
+
+0000000012340000 <foo>:
+    12340000:	94000018 	bl	12340060 <___veneer>
+    12340004:	9400003d 	bl	123400f8 <___veneer>
+    12340008:	9400002a 	bl	123400b0 <___veneer>
+    1234000c:	94000023 	bl	12340098 <___veneer>
+    12340010:	9400002e 	bl	123400c8 <___veneer>
+    12340014:	94000033 	bl	123400e0 <___veneer>
+    12340018:	9400001a 	bl	12340080 <___veneer>
+
+000000001234001c <bar>:
+    1234001c:	1400000b 	b	12340048 <__foo_veneer>
+    12340020:	14000010 	b	12340060 <___veneer>
+    12340024:	14000035 	b	123400f8 <___veneer>
+    12340028:	14000022 	b	123400b0 <___veneer>
+    1234002c:	1400001b 	b	12340098 <___veneer>
+    12340030:	14000026 	b	123400c8 <___veneer>
+    12340034:	1400002b 	b	123400e0 <___veneer>
+    12340038:	14000012 	b	12340080 <___veneer>
+    1234003c:	00000000 	udf	#0
+    12340040:	14000034 	b	12340110 <___veneer\+0x18>
+    12340044:	d503201f 	nop
+
+0000000012340048 <__foo_veneer>:
+    12340048:	90f6e6d0 	adrp	x16, 18000 <\.plt>
+    1234004c:	9100e210 	add	x16, x16, #0x38
+    12340050:	d61f0200 	br	x16
+	\.\.\.
+
+0000000012340060 <___veneer>:
+    12340060:	90f6e710 	adrp	x16, 20000 <_start>
+    12340064:	9100c210 	add	x16, x16, #0x30
+    12340068:	d61f0200 	br	x16
+	\.\.\.
+
+0000000012340078 <___bti_veneer>:
+    12340078:	d503245f 	bti	c
+    1234007c:	17ffffe8 	b	1234001c <bar>
+
+0000000012340080 <___veneer>:
+    12340080:	90f6e710 	adrp	x16, 20000 <_start>
+    12340084:	91009210 	add	x16, x16, #0x24
+    12340088:	d61f0200 	br	x16
+	\.\.\.
+
+0000000012340098 <___veneer>:
+    12340098:	90f6e710 	adrp	x16, 20000 <_start>
+    1234009c:	91006210 	add	x16, x16, #0x18
+    123400a0:	d61f0200 	br	x16
+	\.\.\.
+
+00000000123400b0 <___veneer>:
+    123400b0:	90f6e710 	adrp	x16, 20000 <_start>
+    123400b4:	91005210 	add	x16, x16, #0x14
+    123400b8:	d61f0200 	br	x16
+	\.\.\.
+
+00000000123400c8 <___veneer>:
+    123400c8:	90f6e710 	adrp	x16, 20000 <_start>
+    123400cc:	91007210 	add	x16, x16, #0x1c
+    123400d0:	d61f0200 	br	x16
+	\.\.\.
+
+00000000123400e0 <___veneer>:
+    123400e0:	90f6e710 	adrp	x16, 20000 <_start>
+    123400e4:	91008210 	add	x16, x16, #0x20
+    123400e8:	d61f0200 	br	x16
+	\.\.\.
+
+00000000123400f8 <___veneer>:
+    123400f8:	90f6e710 	adrp	x16, 20000 <_start>
+    123400fc:	9100e210 	add	x16, x16, #0x38
+    12340100:	d61f0200 	br	x16
+	\.\.\.
diff --git a/ld/testsuite/ld-aarch64/bti-far-opt.s b/ld/testsuite/ld-aarch64/bti-far-opt.s
new file mode 100644
index 00000000000..516b901f20f
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/bti-far-opt.s
@@ -0,0 +1,53 @@
+	.text
+	.global	_start
+	.type	_start, %function
+_start:
+	bl foo
+	bl bar
+	bl baz
+baz:
+	nop
+baz_bti_:
+	bti
+baz_bti_c:
+	bti c
+baz_bti_j:
+	bti j
+baz_bti_jc:
+	bti jc
+baz_paciasp:
+	paciasp
+baz_pacibsp:
+	pacibsp
+
+	.section	.far,"ax",@progbits
+	.global	foo
+	.type	foo, %function
+foo:
+	bl baz
+	bl baz_bti_
+	bl baz_bti_c
+	bl baz_bti_j
+	bl baz_bti_jc
+	bl baz_paciasp
+	bl baz_pacibsp
+bar:
+	b foo
+	b baz
+	b baz_bti_
+	b baz_bti_c
+	b baz_bti_j
+	b baz_bti_jc
+	b baz_paciasp
+	b baz_pacibsp
+
+	.section	.note.gnu.property,"a"
+	.align	3
+	.word	4
+	.word	16
+	.word	5
+	.string	"GNU"
+	.word	0xc0000000
+	.word	4
+	.word	1
+	.align	3