m68k: tag floating-point ABI used

This patch adds GNU attribute support to m68k and utilises it to tag the
floating-point calling convention used (hard-float or soft-float). It enables
the linker to ensure linked objects use a consistent floating-point ABI and
allows tools like GDB to infer the ABI used from the ELF file. It is based on
similar work done for PowerPC.

bfd/
	* elf32-m68k.c (m68k_elf_merge_obj_attributes): New function.
	(elf32_m68k_merge_private_bfd_data): Merge GNU attributes.
binutils/
	* readelf.c (display_m68k_gnu_attribute): New function.
	(process_arch_specific): Call display_m68k_gnu_attribute for EM_68K.
gas/
	* config/tc-m68k.c (m68k_elf_gnu_attribute): New function.
	(md_pseudo_table): Handle "gnu_attribute".
	* doc/as.texi: Document GNU attribute for M68K.
include/
	* elf/m68k.h: Add enum for GNU object attribute with floating point
	tag name and values.
ld/
	* testsuite/ld-m68k/attr-gnu-4-0.s: New file.
	* testsuite/ld-m68k/attr-gnu-4-1.s: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-2.s: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-00.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-01.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-02.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-10.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-11.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-12.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-20.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-21.d: Likewise.
	* testsuite/ld-m68k/attr-gnu-4-22.d: Likewise.
	* testsuite/ld-m68k/m68k.exp: Run the new tests.

14 files changed, 89 insertions, 0 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 6f58650..4a38fa8 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,19 @@
+2020-06-26  Pat Bernardi  <bernardi@adacore.com>
+
+	* testsuite/ld-m68k/attr-gnu-4-0.s: New file.
+	* testsuite/ld-m68k/attr-gnu-4-1.s: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-2.s: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-00.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-01.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-02.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-10.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-11.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-12.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-20.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-21.d: Likewise.
+	* testsuite/ld-m68k/attr-gnu-4-22.d: Likewise.
+	* testsuite/ld-m68k/m68k.exp: Run the new tests.
+
 2020-06-24  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/26165
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-0.s b/ld/testsuite/ld-m68k/attr-gnu-4-0.s
new file mode 100644
index 0000000..a143746
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-0.s
@@ -0,0 +1 @@
+.gnu_attribute 4,0
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-00.d b/ld/testsuite/ld-m68k/attr-gnu-4-00.d
new file mode 100644
index 0000000..467ad60
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-00.d
@@ -0,0 +1,4 @@
+#source: attr-gnu-4-0.s
+#source: attr-gnu-4-0.s
+#ld: -r
+#readelf: -A
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-01.d b/ld/testsuite/ld-m68k/attr-gnu-4-01.d
new file mode 100644
index 0000000..1e7fef0
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-01.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-0.s
+#source: attr-gnu-4-1.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: hard float
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-02.d b/ld/testsuite/ld-m68k/attr-gnu-4-02.d
new file mode 100644
index 0000000..cc3945a
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-02.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-0.s
+#source: attr-gnu-4-2.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: soft float
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-1.s b/ld/testsuite/ld-m68k/attr-gnu-4-1.s
new file mode 100644
index 0000000..e985a56
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-1.s
@@ -0,0 +1 @@
+.gnu_attribute 4,1
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-10.d b/ld/testsuite/ld-m68k/attr-gnu-4-10.d
new file mode 100644
index 0000000..a6a798b
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-10.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-1.s
+#source: attr-gnu-4-0.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: hard float
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-11.d b/ld/testsuite/ld-m68k/attr-gnu-4-11.d
new file mode 100644
index 0000000..ecc66a4
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-11.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-1.s
+#source: attr-gnu-4-1.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: hard float
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-12.d b/ld/testsuite/ld-m68k/attr-gnu-4-12.d
new file mode 100644
index 0000000..49526b1
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-12.d
@@ -0,0 +1,4 @@
+#source: attr-gnu-4-1.s
+#source: attr-gnu-4-2.s
+#ld: -r
+#error: .* uses hard float, .* uses soft float.*
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-2.s b/ld/testsuite/ld-m68k/attr-gnu-4-2.s
new file mode 100644
index 0000000..54ebf4e
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-2.s
@@ -0,0 +1 @@
+.gnu_attribute 4,2
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-20.d b/ld/testsuite/ld-m68k/attr-gnu-4-20.d
new file mode 100644
index 0000000..92b410a
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-20.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-2.s
+#source: attr-gnu-4-0.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: soft float
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-21.d b/ld/testsuite/ld-m68k/attr-gnu-4-21.d
new file mode 100644
index 0000000..390dada
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-21.d
@@ -0,0 +1,4 @@
+#source: attr-gnu-4-2.s
+#source: attr-gnu-4-1.s
+#ld: -r
+#error: .* uses hard float, .* uses soft float.*
diff --git a/ld/testsuite/ld-m68k/attr-gnu-4-22.d b/ld/testsuite/ld-m68k/attr-gnu-4-22.d
new file mode 100644
index 0000000..cfa9b35
--- /dev/null
+++ b/ld/testsuite/ld-m68k/attr-gnu-4-22.d
@@ -0,0 +1,8 @@
+#source: attr-gnu-4-2.s
+#source: attr-gnu-4-2.s
+#ld: -r
+#readelf: -A
+
+Attribute Section: gnu
+File Attributes
+  Tag_GNU_M68K_ABI_FP: soft float
diff --git a/ld/testsuite/ld-m68k/m68k.exp b/ld/testsuite/ld-m68k/m68k.exp
index df859ba..610b435 100644
--- a/ld/testsuite/ld-m68k/m68k.exp
+++ b/ld/testsuite/ld-m68k/m68k.exp
@@ -92,3 +92,13 @@ if { [istarget m68k-*-linux*] } then {
 
     run_ld_link_tests $m68k_tls_tests
 }
+
+run_dump_test "attr-gnu-4-00"
+run_dump_test "attr-gnu-4-01"
+run_dump_test "attr-gnu-4-02"
+run_dump_test "attr-gnu-4-10"
+run_dump_test "attr-gnu-4-11"
+run_dump_test "attr-gnu-4-12"
+run_dump_test "attr-gnu-4-20"
+run_dump_test "attr-gnu-4-21"
+run_dump_test "attr-gnu-4-22"