Rework the R_NEG support on both gas and ld for the PowerPC AIX targets, in order to manage C++ exceptions built with GCC.

bfd	PR binutils/21700
	* reloc.c (BFD_RELOC_PPC_NEG): New relocation.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.
	* coff-rs6000.c (_bfd_xcoff_reloc_type_lookup): Add
	BFD_RELOC_PPC_NEG handler.
	(xcoff_reloc_type_neg): Correctly substract addend.
	* coff64-rs6000.c (xcoff64_howto_table): Add R_NEG_32
	howto.
	(xcoff64_rtype2howto): Add handler for R_NEG_32.
	(xcoff64_reloc_type_lookup): Add BFD_RELOC_PPC_NEG handler.
	* xcofflink.c (xcoff_need_ldrel_p): Check output section
	for R_POS-like relocations. New argument added.
	(xcoff_mark): Adapt to new xcoff_need_ldrel_p argument.
	(xcoff_link_input_bfd): Likewise.

gas	* config/tc-ppc.c (ppc_get_csect_to_adjust): New function.
	(ppc_fix_adjustable): Manage fx_subsy part.
	(tc_gen_reloc): Create second relocation when both
	fx_addsy and fx_subsy are provided.
	* config/tc-ppc.h (RELOC_EXPANSION_POSSIBLE): New define.
	(MAX_RELOC_EXPANSION): Likewise.
	(TC_FORCE_RELOCATION_SUB_SAME): Likewise
	(UNDEFINED_DIFFERENCE_OK): Likewise
	* testsuite/gas/all/gas.exp: Skip difference between two
	undefined symbols test.

ld	* testsuite/ld-powerpc/aix52.exp: Add new test.
	* testsuite/ld-powerpc/aix-neg-reloc-32.d: New test.
	* testsuite/ld-powerpc/aix-neg-reloc-64.d: New test.
	* testsuite/ld-powerpc/aix-neg-reloc.ex: New test.
	* testsuite/ld-powerpc/aix-neg-reloc.s: New test.

5 files changed, 83 insertions, 0 deletions

diff --git a/ld/testsuite/ld-powerpc/aix-neg-reloc-32.d b/ld/testsuite/ld-powerpc/aix-neg-reloc-32.d
new file mode 100644
index 0000000..4e980f0
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/aix-neg-reloc-32.d
@@ -0,0 +1,23 @@
+#source: aix-tls-reloc.s
+#as: -a32
+#ld: -b32 -shared -bE:aix-tls-reloc.ex
+#objdump: -dr
+#target: [is_xcoff_format]
+
+.*
+
+Disassembly of section \.text:
+
+.* <.foo>:
+.*:	4e 80 00 20 	br
+.*: R_REF	_foo.ro_-.*
+.*:	60 00 00 00 	oril    r0,r0,0
+.*:	60 00 00 00 	oril    r0,r0,0
+.*:	60 00 00 00 	oril    r0,r0,0
+.* <_GLOBAL__F_foo>:
+.*:	ff ff ff f0 	.long 0xfffffff0
+.*: R_POS	.text-.*
+.*: R_NEG	_foo.ro_-.*
+.*:	60 00 00 00 	oril    r0,r0,0
+.*:	60 00 00 00 	oril    r0,r0,0
+.*:	60 00 00 00 	oril    r0,r0,0
diff --git a/ld/testsuite/ld-powerpc/aix-neg-reloc-64.d b/ld/testsuite/ld-powerpc/aix-neg-reloc-64.d
new file mode 100644
index 0000000..9cf16d0
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/aix-neg-reloc-64.d
@@ -0,0 +1,23 @@
+#source: aix-tls-reloc.s
+#as: -a32
+#ld: -b32 -shared -bE:aix-tls-reloc.ex
+#objdump: -dr
+#target: [is_xcoff_format]
+
+.*
+
+Disassembly of section \.text:
+
+.* <.foo>:
+.*:	4e 80 00 20 	blr
+.*: R_REF	_foo.ro_-.*
+.*:	60 00 00 00 	nop
+.*:	60 00 00 00 	nop
+.*:	60 00 00 00 	nop
+.* <_GLOBAL__F_foo>:
+.*:	ff ff ff ff 	fnmadd. f31,f31,f31,f31
+.*: R_POS_64	.text-.*
+.*: R_NEG	_foo.ro_-.*
+.*:	ff ff ff f0 	.long 0xfffffff0
+.*:	60 00 00 00 	nop
+.*:	60 00 00 00 	nop
diff --git a/ld/testsuite/ld-powerpc/aix-neg-reloc.ex b/ld/testsuite/ld-powerpc/aix-neg-reloc.ex
new file mode 100644
index 0000000..257cc56
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/aix-neg-reloc.ex
@@ -0,0 +1 @@
+foo
diff --git a/ld/testsuite/ld-powerpc/aix-neg-reloc.s b/ld/testsuite/ld-powerpc/aix-neg-reloc.s
new file mode 100644
index 0000000..20b48bd
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/aix-neg-reloc.s
@@ -0,0 +1,30 @@
+  .toc
+  .csect .text[PR]
+  .globl foo
+  .globl .foo
+  .csect foo[DS],3
+foo:
+  .if size == 32
+  .long	.foo, TOC[tc0], 0
+  .else
+  .llong .foo, TOC[tc0], 0
+  .endif
+
+  .csect .text[PR]
+.foo:
+LFB..0:
+  blr
+
+  .csect _foo.ro_[RO],4
+  .globl _GLOBAL__F_foo
+_GLOBAL__F_foo:
+  .if size == 32
+  .vbyte 4,LFB..0-$
+  .else
+  .vbyte 8,LFB..0-$
+  .endif
+
+# Make sure that .ref is also enough to keep _GLOBAL__F_foo
+# when exporting foo.
+  .csect .text[PR]
+  .ref _GLOBAL__F_foo
diff --git a/ld/testsuite/ld-powerpc/aix52.exp b/ld/testsuite/ld-powerpc/aix52.exp
index 0e68b6a..51d3132 100644
--- a/ld/testsuite/ld-powerpc/aix52.exp
+++ b/ld/testsuite/ld-powerpc/aix52.exp
@@ -251,6 +251,12 @@ set aix52tests {
      "" {aix-toc-1a.s aix-toc-1b.s}
      {{objdump -dr aix-toc-1-SIZE.dd}}
      "aix-toc-1.so"}
+
+    {"Negative relocation test 1" "-shared -bE:aix-neg-reloc.ex"
+	"" {aix-neg-reloc.s}
+	{{objdump -dr aix-neg-reloc-SIZE.d}}
+	"aix-neg-reloc.so"}
+
 }
 
 foreach test $aix52tests {