Enhance powerpc ld -r --relax

One of the ill effects of ld -r is to mash together sections.  That
can result in reduced icache performance at runtime due to unexpected
movement of code.  Another problem is that sections can become too
large to link on targets that have limited relative addressing.  ld -r
--relax attempts to overcome the large section problem for branches by
inserting trampolines, but the powerpc support added lots of
unnecessary trampolines.  This patch trims them somewhat.

bfd/
	* elf32-ppc.c (ppc_elf_relax_section): Ignore common or undef locals.
	Avoid trashing toff with added when used as a symbol index.
	Ignore R_PPC_PLTREL24 addends in unused example code.  Avoid
	creating unnecessary fixups when relocatable.
ld/
	* testsuite/ld-powerpc/big.s: New file.
	* testsuite/ld-powerpc/relaxrl.d: New test.
	* testsuite/ld-powerpc/powerpc.exp: Run new test.
	* testsuite/ld-powerpc/relaxr.d: Adjust.

5 files changed, 47 insertions, 18 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index ecbbf48..0b3058b 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,10 @@
+2018-07-25  Alan Modra  <amodra@gmail.com>
+
+	* testsuite/ld-powerpc/big.s: New file.
+	* testsuite/ld-powerpc/relaxrl.d: New test.
+	* testsuite/ld-powerpc/powerpc.exp: Run new test.
+	* testsuite/ld-powerpc/relaxr.d: Adjust.
+
 2018-07-24  Nick Clifton  <nickc@redhat.com>
 
 	* po/fr.po: Updated French translation.
diff --git a/ld/testsuite/ld-powerpc/big.s b/ld/testsuite/ld-powerpc/big.s
new file mode 100644
index 0000000..e372c97
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/big.s
@@ -0,0 +1,2 @@
+ .text
+ .space 32*1024*1024
diff --git a/ld/testsuite/ld-powerpc/powerpc.exp b/ld/testsuite/ld-powerpc/powerpc.exp
index 0359ba2..cfeb277 100644
--- a/ld/testsuite/ld-powerpc/powerpc.exp
+++ b/ld/testsuite/ld-powerpc/powerpc.exp
@@ -160,6 +160,9 @@ set ppcelftests {
     {"relocatable relaxing" "-melf32ppc -r --relax" "" "-a32" "relax.s"
      {{objdump -dr relaxr.d}}
      "rrelax"}
+    {"relocatable relaxing large" "-melf32ppc -r --relax" "" "-a32" "relax.s big.s"
+     {{objdump -dr relaxrl.d}}
+     "rrelax"}
 }
 
 set ppc64elftests {
diff --git a/ld/testsuite/ld-powerpc/relaxr.d b/ld/testsuite/ld-powerpc/relaxr.d
index 3ce2751..1b3a3c1 100644
--- a/ld/testsuite/ld-powerpc/relaxr.d
+++ b/ld/testsuite/ld-powerpc/relaxr.d
@@ -4,23 +4,13 @@
 Disassembly of section .text:
 
 00000000 <_start>:
-   0:	(48 00 00 15|15 00 00 48) 	bl      14 <_start\+0x14>
-   4:	(48 00 00 21|21 00 00 48) 	bl      24 <_start\+0x24>
-   8:	(48 00 00 0d|0d 00 00 48) 	bl      14 <_start\+0x14>
-			8: R_PPC_NONE	\*ABS\*
-   c:	(48 00 00 19|19 00 00 48) 	bl      24 <_start\+0x24>
-			c: R_PPC_NONE	\*ABS\*
+   0:	(48 00 00 01|01 00 00 48) 	bl      0 <_start>
+			0: R_PPC_REL24	near
+   4:	(48 00 00 01|01 00 00 48) 	bl      4 <_start\+0x4>
+			4: R_PPC_REL24	far
+   8:	(48 00 00 01|01 00 00 48) 	bl      8 <_start\+0x8>
+			8: R_PPC_REL24	near
+   c:	(48 00 00 01|01 00 00 48) 	bl      c <_start\+0xc>
+			c: R_PPC_REL24	far
   10:	(48 00 00 00|00 00 00 48) 	b       10 <_start\+0x10>
 			10: R_PPC_REL24	_start
-  14:	(3d 80 00 00|00 00 80 3d) 	lis     r12,0
-			1(6|4): R_PPC_ADDR16_HA	near
-  18:	(39 8c 00 00|00 00 8c 39) 	addi    r12,r12,0
-			1(a|8): R_PPC_ADDR16_LO	near
-  1c:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
-  20:	(4e 80 04 20|20 04 80 4e) 	bctr
-  24:	(3d 80 00 00|00 00 80 3d) 	lis     r12,0
-			2(6|4): R_PPC_ADDR16_HA	far
-  28:	(39 8c 00 00|00 00 8c 39) 	addi    r12,r12,0
-			2(a|8): R_PPC_ADDR16_LO	far
-  2c:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
-  30:	(4e 80 04 20|20 04 80 4e) 	bctr
diff --git a/ld/testsuite/ld-powerpc/relaxrl.d b/ld/testsuite/ld-powerpc/relaxrl.d
new file mode 100644
index 0000000..8557e3f
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/relaxrl.d
@@ -0,0 +1,27 @@
+
+.*:     file format .*
+
+Disassembly of section .text:
+
+0+ <_start>:
+ +0:	(48 00 00 15|15 00 00 48) 	bl      14 <_start\+0x14>
+ +4:	(48 00 00 21|21 00 00 48) 	bl      24 <_start\+0x24>
+ +8:	(48 00 00 0d|0d 00 00 48) 	bl      14 <_start\+0x14>
+			8: R_PPC_NONE	\*ABS\*
+ +c:	(48 00 00 19|19 00 00 48) 	bl      24 <_start\+0x24>
+			c: R_PPC_NONE	\*ABS\*
+ +10:	(48 00 00 00|00 00 00 48) 	b       10 <_start\+0x10>
+			10: R_PPC_REL24	_start
+ +14:	(3d 80 00 00|00 00 80 3d) 	lis     r12,0
+			1(6|4): R_PPC_ADDR16_HA	near
+ +18:	(39 8c 00 00|00 00 8c 39) 	addi    r12,r12,0
+			1(a|8): R_PPC_ADDR16_LO	near
+ +1c:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
+ +20:	(4e 80 04 20|20 04 80 4e) 	bctr
+ +24:	(3d 80 00 00|00 00 80 3d) 	lis     r12,0
+			2(6|4): R_PPC_ADDR16_HA	far
+ +28:	(39 8c 00 00|00 00 8c 39) 	addi    r12,r12,0
+			2(a|8): R_PPC_ADDR16_LO	far
+ +2c:	(7d 89 03 a6|a6 03 89 7d) 	mtctr   r12
+ +30:	(4e 80 04 20|20 04 80 4e) 	bctr
+	\.\.\.