PowerPC64 --plt-align

This changes the PowerPC64 --plt-align option to perform the usual
alignment of code as suggested by its name, as well as the previous
behaviour of padding so as to reduce boundary crossing.  The old
behaviour is had by using a negative parameter.

The default is also changed to align plt stub code by default to 32
byte boundaries, the point being to get better bctr branch prediction
on power8 and power9 hardware.

bfd/
	* elf64-ppp.c (plt_stub_pad): Handle positive and negative
	plt_stub_align.
ld/
	* ld.texinfo (--plt-align): Describe new behaviour of option.
	* emultempl/ppc64elf.em (params): Default plt_stub_align to 5.
	* testsuite/ld-powerpc/powerpc.exp: Pass --no-plt-align for
	selected tests.
	* testsuite/ld-powerpc/relbrlt.d: Pass --no-plt-align.
	* testsuite/ld-powerpc/elfv2so.d: Adjust expected output.

3 files changed, 18 insertions, 14 deletions

diff --git a/ld/testsuite/ld-powerpc/elfv2so.d b/ld/testsuite/ld-powerpc/elfv2so.d
index 2c1fa32..a577b2a 100644
--- a/ld/testsuite/ld-powerpc/elfv2so.d
+++ b/ld/testsuite/ld-powerpc/elfv2so.d
@@ -12,24 +12,28 @@ Disassembly of section \.text:
 .*:	(e9 82 80 38|38 80 82 e9) 	ld      r12,-32712\(r2\)
 .*:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
 .*:	(4e 80 04 20|20 04 80 4e) 	bctr
+	\.\.\.
 
 .* <.*\.plt_call\.f3>:
 .*:	(f8 41 00 18|18 00 41 f8) 	std     r2,24\(r1\)
 .*:	(e9 82 80 28|28 80 82 e9) 	ld      r12,-32728\(r2\)
 .*:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
 .*:	(4e 80 04 20|20 04 80 4e) 	bctr
+	\.\.\.
 
 .* <.*\.plt_call\.f2>:
 .*:	(f8 41 00 18|18 00 41 f8) 	std     r2,24\(r1\)
 .*:	(e9 82 80 30|30 80 82 e9) 	ld      r12,-32720\(r2\)
 .*:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
 .*:	(4e 80 04 20|20 04 80 4e) 	bctr
+	\.\.\.
 
 .* <.*\.plt_call\.f1>:
 .*:	(f8 41 00 18|18 00 41 f8) 	std     r2,24\(r1\)
 .*:	(e9 82 80 40|40 80 82 e9) 	ld      r12,-32704\(r2\)
 .*:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
 .*:	(4e 80 04 20|20 04 80 4e) 	bctr
+	\.\.\.
 
 .* <f1>:
 .*:	(3c 4c 00 02|02 00 4c 3c) 	addis   r2,r12,2
@@ -37,14 +41,14 @@ Disassembly of section \.text:
 .*:	(7c 08 02 a6|a6 02 08 7c) 	mflr    r0
 .*:	(f8 21 ff e1|e1 ff 21 f8) 	stdu    r1,-32\(r1\)
 .*:	(f8 01 00 30|30 00 01 f8) 	std     r0,48\(r1\)
-.*:	(4b ff ff dd|dd ff ff 4b) 	bl      .*\.plt_call\.f1>
+.*:	(4b ff ff cd|cd ff ff 4b) 	bl      .*\.plt_call\.f1>
 .*:	(e8 62 80 08|08 80 62 e8) 	ld      r3,-32760\(r2\)
-.*:	(4b ff ff c5|c5 ff ff 4b) 	bl      .*\.plt_call\.f2>
+.*:	(4b ff ff a5|a5 ff ff 4b) 	bl      .*\.plt_call\.f2>
 .*:	(e8 41 00 18|18 00 41 e8) 	ld      r2,24\(r1\)
 .*:	(e8 62 80 10|10 80 62 e8) 	ld      r3,-32752\(r2\)
-.*:	(4b ff ff a9|a9 ff ff 4b) 	bl      .*\.plt_call\.f3>
+.*:	(4b ff ff 79|79 ff ff 4b) 	bl      .*\.plt_call\.f3>
 .*:	(e8 41 00 18|18 00 41 e8) 	ld      r2,24\(r1\)
-.*:	(4b ff ff 91|91 ff ff 4b) 	bl      .*\.plt_call\.f4>
+.*:	(4b ff ff 51|51 ff ff 4b) 	bl      .*\.plt_call\.f4>
 .*:	(e8 41 00 18|18 00 41 e8) 	ld      r2,24\(r1\)
 .*:	(e8 01 00 30|30 00 01 e8) 	ld      r0,48\(r1\)
 .*:	(38 21 00 20|20 00 21 38) 	addi    r1,r1,32
diff --git a/ld/testsuite/ld-powerpc/powerpc.exp b/ld/testsuite/ld-powerpc/powerpc.exp
index 0735ab7..ef3b718 100644
--- a/ld/testsuite/ld-powerpc/powerpc.exp
+++ b/ld/testsuite/ld-powerpc/powerpc.exp
@@ -163,26 +163,26 @@ set ppcelftests {
 }
 
 set ppc64elftests {
-    {"TLS static exec (markers)" "-melf64ppc" ""
+    {"TLS static exec (markers)" "-melf64ppc --no-plt-align" ""
      "-a64 --defsym TLSMARK=1"  {tls.s tlslib.s}
      {{objdump -dr tls.d} {objdump -sj.got tls.g} {objdump -sj.tdata tls.t}}
      "tlsm"}
-    {"TLS static exec" "-melf64ppc" "" "-a64"  {tls.s tlslib.s}
+    {"TLS static exec" "-melf64ppc --no-plt-align" "" "-a64"  {tls.s tlslib.s}
      {{objdump -dr tls.d} {objdump -sj.got tls.g} {objdump -sj.tdata tls.t}}
      "tls"}
     {"TLS helper shared library" "-shared -melf64ppc tmpdir/tlslib.o" "" "" {}
      {} "libtlslib.so"}
     {"TLS helper old shared lib" "-shared -melf64ppc" "" "-a64" {oldtlslib.s}
      {} "liboldlib.so"}
-    {"TLS dynamic exec" "-melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/libtlslib.so" "" "" {}
+    {"TLS dynamic exec" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/libtlslib.so" "" "" {}
      {{readelf -WSsrl tlsexe.r} {objdump -dr tlsexe.d}
       {objdump -sj.got tlsexe.g} {objdump -sj.tdata tlsexe.t}}
      "tlsexe"}
-    {"TLS dynamic old" "-melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/liboldlib.so" "" "" {}
+    {"TLS dynamic old" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/liboldlib.so" "" "" {}
      {{readelf -WSsrl tlsexe.r} {objdump -dr tlsexe.d}
       {objdump -sj.got tlsexe.g} {objdump -sj.tdata tlsexe.t}}
      "tlsexeold"}
-    {"TLS shared" "-shared -melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o" "" "" {}
+    {"TLS shared" "-shared -melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o" "" "" {}
      {{readelf -WSsrl tlsso.r} {objdump -dr tlsso.d}
       {objdump -sj.got tlsso.g} {objdump -sj.tdata tlsso.t}}
      "tls.so"}
@@ -190,17 +190,17 @@ set ppc64elftests {
      {{objdump -dr tlstoc.d} {objdump -sj.got tlstoc.g}
       {objdump -sj.tdata tlstoc.t}}
      "tlstoc"}
-    {"TLSTOC dynamic exec" "-melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/libtlslib.so" ""
+    {"TLSTOC dynamic exec" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/libtlslib.so" ""
      "" {}
      {{readelf -WSsrl tlsexetoc.r} {objdump -dr tlsexetoc.d}
       {objdump -sj.got tlsexetoc.g} {objdump -sj.tdata tlsexetoc.t}}
      "tlsexetoc"}
-    {"TLSTOC dynamic old" "-melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/liboldlib.so" ""
+    {"TLSTOC dynamic old" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/liboldlib.so" ""
      "" {}
      {{readelf -WSsrl tlsexetoc.r} {objdump -dr tlsexetoc.d}
       {objdump -sj.got tlsexetoc.g} {objdump -sj.tdata tlsexetoc.t}}
      "tlsexetocold"}
-    {"TLSTOC shared" "-shared -melf64ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o" "" "" {}
+    {"TLSTOC shared" "-shared -melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o" "" "" {}
      {{readelf -WSsrl tlstocso.r} {objdump -dr tlstocso.d}
       {objdump -sj.got tlstocso.g} {objdump -sj.tdata tlstocso.t}}
      "tlstoc.so"}
@@ -221,7 +221,7 @@ set ppc64elftests {
      "tlsopt4"}
     {"TLS DLL" "-shared -melf64ppc --version-script tlsdll.ver" "" "-a64" {tlsdll.s}
      {} "tlsdll.so"}
-    {"TLS opt 5" "-melf64ppc -shared --gc-sections --no-plt-localentry tmpdir/tlsdll.so" "" "-a64"  {tlsopt5.s}
+    {"TLS opt 5" "-melf64ppc --no-plt-align -shared --gc-sections --no-plt-localentry tmpdir/tlsdll.so" "" "-a64"  {tlsopt5.s}
      {{objdump -dr tlsopt5.d} {readelf -wf tlsopt5.wf}}
      "tlsopt5"}
     {"sym@tocbase" "-shared -melf64ppc" "" "-a64" {symtocbase-1.s symtocbase-2.s}
diff --git a/ld/testsuite/ld-powerpc/relbrlt.d b/ld/testsuite/ld-powerpc/relbrlt.d
index a5f2437..a00b1ff 100644
--- a/ld/testsuite/ld-powerpc/relbrlt.d
+++ b/ld/testsuite/ld-powerpc/relbrlt.d
@@ -1,6 +1,6 @@
 #source: relbrlt.s
 #as: -a64
-#ld: -melf64ppc --no-ld-generated-unwind-info --emit-relocs
+#ld: -melf64ppc --no-plt-align --no-ld-generated-unwind-info --emit-relocs
 #objdump: -Dr
 
 .*