libctf: don't run tests requiring deduplicating linker unless one is in use

Before now, we were relying on gcc -B to repoint GCC at our freshly-built
linker, and assuming we could use this to run tests that do linker dedup.

This is, alas, not reliable (building --with-ld=/an/absolute/path bypasses
-B searches for the linker), and we would like the libctf tests in
particular to not fail if the compiler uses a linker that cannot deduplicate
(simply skipping such tests).

Add a new testsuite function that tries to link one of the lookup tests'
testcases (which is known to produce conflicting types, i.e. a dict with
per-translation-unit children) and then does an objdump and greps it for
signs of the per-translation-unit children.  If there are none, the linker
probably just concatenated the sections: i.e., it is not a linker that
can deduplicate CTF.

libctf/
	PR libctf/33162
	* testsuite/config/default.exp (objdump): Introduce.
	(OBJDUMPFLAGS): Likewise.
	* testsuite/lib/ctf-lib.exp (check_ctf_linker_dedup): New.
	* testsuite/libctf-lookup/lookup.exp: Use it.
	* testsuite/libctf-regression/libctf-repeat-cu.exp: Likewise.
	* testsuite/libctf-regression/regression.exp: Likewise.

libctf/configure

@@ -15966,6 +15966,14 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
+case "${host}" in
+  # PR libctf/29292
+  # libctf's use of mmap doesn't work on Solaris 11.4, so disable it.
+  *-*-solaris2.11*)
+    ac_cv_func_mmap_fixed_mapped=no
+  ;;
+esac
+
 
 
 
@@ -17015,7 +17023,7 @@ if test -n "$decommented_version_script"; then
    # used by GNU ld.  Use cpp to strip the comments out.  (cpp exists under this
    # name on all platforms that support ld -z gnu-version-script.)
    /lib/cpp < $srcdir/libctf.ver > libctf-decommented.ver
-   /lib/cpp < $srcdir/libctf-nobfd.ver > libctf-nobfd-decommented.ver
+   /lib/cpp < libctf-nobfd.ver > libctf-nobfd-decommented.ver
    VERSION_FLAGS="$ac_cv_libctf_version_script='libctf-decommented.ver'"
    VERSION_FLAGS_NOBFD="$ac_cv_libctf_version_script='libctf-nobfd-decommented.ver'"
 elif test -z "$no_version_script"; then

libctf/configure.ac

@@ -65,6 +65,14 @@ AM_MAINTAINER_MODE
 AM_INSTALL_LIBBFD
 ACX_PROG_CC_WARNING_OPTS([-Wall], [ac_libctf_warn_cflags])
 
+case "${host}" in
+  # PR libctf/29292
+  # libctf's use of mmap doesn't work on Solaris 11.4, so disable it.
+  *-*-solaris2.11*)
+    ac_cv_func_mmap_fixed_mapped=no
+  ;;
+esac
+
 GCC_AC_FUNC_MMAP
 # Needed for BFD capability checks.
 AC_SEARCH_LIBS(dlsym, dl)
@@ -293,7 +301,7 @@ if test -n "$decommented_version_script"; then
    # used by GNU ld.  Use cpp to strip the comments out.  (cpp exists under this
    # name on all platforms that support ld -z gnu-version-script.)
    /lib/cpp < $srcdir/libctf.ver > libctf-decommented.ver
-   /lib/cpp < $srcdir/libctf-nobfd.ver > libctf-nobfd-decommented.ver
+   /lib/cpp < libctf-nobfd.ver > libctf-nobfd-decommented.ver
    VERSION_FLAGS="$ac_cv_libctf_version_script='libctf-decommented.ver'"
    VERSION_FLAGS_NOBFD="$ac_cv_libctf_version_script='libctf-nobfd-decommented.ver'"
 elif test -z "$no_version_script"; then

libctf/ctf-serialize.c

@@ -74,6 +74,12 @@ ctf_symtab_skippable (ctf_link_sym_t *sym)
 	  || sym->st_shndx == SHN_UNDEF
 	  || strcmp (sym->st_name, "_START_") == 0
 	  || strcmp (sym->st_name, "_END_") == 0
+	  || strcmp (sym->st_name, "_DYNAMIC") == 0
+	  || strcmp (sym->st_name, "_GLOBAL_OFFSET_TABLE_") == 0
+	  || strcmp (sym->st_name, "_PROCEDURE_LINKAGE_TABLE_") == 0
+	  || strcmp (sym->st_name, "_edata") == 0
+	  || strcmp (sym->st_name, "_end") == 0
+	  || strcmp (sym->st_name, "_etext") == 0
 	  || (sym->st_type == STT_OBJECT && sym->st_shndx == SHN_EXTABS
 	      && sym->st_value == 0));
 }

libctf/testsuite/config/default.exp

@@ -34,6 +34,10 @@ if ![info exists as] then {
     set as [findfile $base_dir/../gas/as-new $base_dir/../gas/as-new [transform as]]
 }
 
+if ![info exists objdump] then {
+    set objdump [findfile $base_dir/../binutils/objdump]
+}
+
 remote_exec host "mkdir -p tmpdir"
 
 # Make symlinks from tmpdir/libctf to the linker and assembler in the
@@ -63,10 +67,12 @@ if {![info exists CFLAGS_FOR_TARGET]} {
 if ![info exists AR] then {
     set AR [findfile $base_dir/../binutils/ar]
 }
-
 if {![info exists OBJDUMP]} {
     set OBJDUMP [findfile $base_dir/../binutils/objdump]
 }
+if ![info exists OBJDUMPFLAGS] then {
+    set OBJDUMPFLAGS {}
+}
 
 # load the utility procedures
 load_lib ctf-lib.exp

libctf/testsuite/lib/ctf-lib.exp

@@ -20,6 +20,51 @@
 
 load_file $srcdir/../../ld/testsuite/lib/ld-lib.exp
 
+# Returns true if the target linker deduplicates CTF.
+proc check_ctf_linker_dedup { } {
+    global ctf_linker_dedup_saved
+
+    if {![info exists ctf_linker_dedup_saved]} {
+	set ctf_linker_dedup_saved 0
+
+	if ([check_ctf_available]) {
+	    global objdump srcdir
+
+	    set basename "tmpdir/ctf_linker_dedups[pid]"
+	    compile_one_cc $srcdir/libctf-lookup/ambiguous-struct-A.c ${basename}-A.o "-gctf -fPIC -c"
+	    compile_one_cc $srcdir/libctf-lookup/ambiguous-struct-B.c ${basename}-B.o "-gctf -fPIC -c"
+	    compile_one_cc "${basename}-A.o ${basename}-B.o" $basename.so "-gctf -fPIC -shared"
+	    if {! [remote_file host exists $basename.so] } {
+		return 0
+	    }
+
+	    # Don't use run_host_cmd: it dumps the entire output into the log,
+	    # even on success.
+	    set cmdret [remote_exec host [concat sh -c [list "$objdump --ctf $basename.so >dump.out 2>dump.err"]] "" "/dev/null"]
+	    set cmdret [lindex $cmdret 0]
+	    remote_upload host "dump.out"
+	    remote_upload host "dump.err"
+	    set dump_out [prune_warnings [file_contents "dump.out"]]
+	    set dump_err [prune_warnings [file_contents "dump.err"]]
+	    remote_file host delete "dump.out" "dump.err"
+	    remote_file build delete "dump.out" "dump.err"
+
+	    if {$cmdret != 0} {
+		verbose -log "failed with $cmdret: stderr: $dump_err"
+		verbose -log "output: $dump_out"
+		return 0;
+	    }
+
+	    remote_file host delete $basename.so ${basename}-A.o ${basename}-B.o
+	    if [regexp {CTF archive member: } $dump_out] {
+		set ctf_linker_dedup_saved 1
+	    }
+	}
+    }
+    return $ctf_linker_dedup_saved
+}
+
+
 proc run_native_host_cmd { command } {
     global link_output
     global ld

libctf/testsuite/libctf-lookup/lookup.exp

@@ -28,6 +28,11 @@ if {![check_ctf_available]} {
     return 0
 }
 
+if {![check_ctf_linker_dedup]} {
+    unsupported "no CTF deduplication support in the linker"
+    return 0
+}
+
 if {[info exists env(LC_ALL)]} {
     set old_lc_all $env(LC_ALL)
 }

libctf/testsuite/libctf-regression/libctf-repeat-cu.exp

@@ -37,6 +37,11 @@ if {![check_ctf_available]} {
     return 0
 }
 
+if {![check_ctf_linker_dedup]} {
+    unsupported "no CTF deduplication support in the linker"
+    return 0
+}
+
 if {[info exists env(LC_ALL)]} {
     set old_lc_all $env(LC_ALL)
 }

libctf/testsuite/libctf-regression/regression.exp

@@ -23,6 +23,11 @@ if {![check_ctf_available]} {
     return 0
 }
 
+if {![check_ctf_linker_dedup]} {
+    unsupported "no CTF deduplication support in the linker"
+    return 0
+}
+
 if ![is_elf_format] {
     unsupported "CTF needs bfd changes to be emitted on non-ELF"
     return 0