gdb/testsuite: fix fission support in the Dwarf assembler

This commit fixes fission support in the Dwarf assembler. I added the
new test gdb.dwarf2/fission-absolute-dwo.exp which is a simple example
of using the fission support.  I also rewrote the existing test
gdb.dwarf2/fission-multi-cu.exp to use the new functionality (instead
of using an x86-64 only assembler file).

To better support compiling the assembler files produced by the Dwarf
assembler I have added the new proc build_executable_and_dwo_files in
lib/dwarf.exp, this replaces build_executable_from_fission_assembler,
all the tests that used the old proc have been updated.  Where the old
proc assumed a single .S source file which contained the entire test,
the new proc allows for multiple source files.

The Dwarf assembler already had some fission support, however, this
was not actually used in any tests, and when I tried using it there
were a few issues.

The biggest change is that we now generate DW_FORM_GNU_addr_index
instead of DW_FORM_addr for the low and high pc in
_handle_macro_at_range, support for the DW_FORM_GNU_addr_index is new
in this commit.

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/fission-absolute-dwo.c: New file.
	* gdb.dwarf2/fission-absolute-dwo.exp: New file.
	* gdb.dwarf2/fission-base.exp: Use build_executable_and_dwo_files
	instead of build_executable_from_fission_assembler.
	* gdb.dwarf2/fission-loclists-pie.exp: Likewise.
	* gdb.dwarf2/fission-loclists.exp: Likewise.

1 files changed, 217 insertions, 44 deletions

diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index b9a4938..f6a3574 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -28,39 +28,12 @@ proc dwarf2_support {} {
     return 0
 }
 
-# Build an executable from a fission-based .S file.
-# This handles the extra work of splitting the .o into non-dwo and dwo
-# pieces, making sure the .dwo is available if we're using cc-with-tweaks.sh
-# to build a .dwp file.
-# The arguments and results are the same as for build_executable.
+# Use 'objcopy --extract-dwo to extract DWO information from
+# OBJECT_FILE and place it into DWO_FILE.
 #
-# Current restrictions:
-# - only supports one source file
-# - cannot be run on remote hosts
-
-proc build_executable_from_fission_assembler { testname executable sources options } {
-    verbose -log "build_executable_from_fission_assembler $testname $executable $sources $options"
-    if { [llength $sources] != 1 } {
-	error "Only one source file supported."
-    }
-    if [is_remote host] {
-	error "Remote hosts are not supported."
-    }
-
-    global srcdir subdir
-    set source_file ${srcdir}/${subdir}/${sources}
-    set root_name [file rootname [file tail $source_file]]
-    set output_base [standard_output_file $root_name]
-    set object_file ${output_base}.o
-    set dwo_file ${output_base}.dwo
-    set object_options "object $options"
+# Return 0 on success, otherwise, return -1.
+proc extract_dwo_information { object_file dwo_file } {
     set objcopy [gdb_find_objcopy]
-
-    set result [gdb_compile $source_file $object_file object $options]
-    if { "$result" != "" } {
-	return -1
-    }
-
     set command "$objcopy --extract-dwo $object_file $dwo_file"
     verbose -log "Executing $command"
     set result [catch "exec $command" output]
@@ -68,19 +41,157 @@ proc build_executable_from_fission_assembler { testname executable sources optio
     if { $result == 1 } {
 	return -1
     }
+    return 0
+}
 
-    set command "$objcopy --strip-dwo $object_file"
+# Use 'objcopy --strip-dwo to remove DWO information from
+# FILENAME.
+#
+# Return 0 on success, otherwise, return -1.
+proc strip_dwo_information { filename } {
+    set objcopy [gdb_find_objcopy]
+    set command "$objcopy --strip-dwo $filename"
     verbose -log "Executing $command"
     set result [catch "exec $command" output]
     verbose -log "objcopy --strip-dwo output: $output"
     if { $result == 1 } {
 	return -1
     }
+    return 0
+}
 
-    set result [gdb_compile $object_file $executable executable $options]
-    if { "$result" != "" } {
+# Build an executable, with the debug information split out into a
+# separate .dwo file.
+#
+# This function is based on build_executable_from_specs in
+# lib/gdb.exp, but with threading support, and rust support removed.
+#
+# TESTNAME is the name of the test; this is passed to 'untested' if
+# something fails.
+#
+# EXECUTABLE is the executable to create, this can be an absolute
+# path, or a relative path, in which case the EXECUTABLE will be
+# created in the standard output directory.
+#
+# OPTIONS is passed to the final link, using gdb_compile.  If OPTIONS
+# contains any option that indicates threads is required, of if the
+# option rust is included, then this function will return failure.
+#
+# ARGS is a series of lists.  Each list is a spec for one source file
+# that will be compiled to make EXECUTABLE.  Each spec in ARGS has the
+# form:
+#	[ SOURCE OPTIONS ]
+# or:
+#       [ SOURCE OPTIONS OBJFILE ]
+#
+# Where SOURCE is the path to the source file to compile.  This can be
+# absolute, or relative to the standard global ${subdir}/${srcdir}/
+# path.
+#
+# OPTIONS are the options to use when compiling SOURCE into an object
+# file.
+#
+# OBJFILE is optional, if present this is the name of the object file
+# to create for SOURCE.  If this is not provided then a suitable name
+# will be auto-generated.
+#
+# If OPTIONS contains the option 'split-dwo' then the debug
+# information is extracted from the object file created by compiling
+# SOURCE and placed into a file with a dwo extension.  The name of
+# this file is generated based on the name of the object file that was
+# created (with the .o replaced with .dwo).
+proc build_executable_and_dwo_files { testname executable options args } {
+    global subdir
+    global srcdir
+
+    if { ! [regexp "^/" "$executable"] } then {
+	set binfile [standard_output_file $executable]
+    } else {
+	set binfile $executable
+    }
+
+    set info_options ""
+    if { [lsearch -exact $options "c++"] >= 0 } {
+	set info_options "c++"
+    }
+    if [get_compiler_info ${info_options}] {
+        return -1
+    }
+
+    set func gdb_compile
+    if {[lsearch -regexp $options \
+	     {^(pthreads|shlib|shlib_pthreads|openmp)$}] != -1} {
+	# Currently don't support compiling thread based tests here.
+	# If this is required then look to build_executable_from_specs
+	# for inspiration.
 	return -1
     }
+    if {[lsearch -exact $options rust] != -1} {
+	# Currently don't support compiling rust tests here.  If this
+	# is required then look to build_executable_from_specs for
+	# inspiration.
+	return -1
+    }
+
+    # Must be run on local host due to use of objcopy.
+    if [is_remote host] {
+	return -1
+    }
+
+    set objects {}
+    set i 0
+    foreach spec $args {
+	if {[llength $spec] < 2} {
+	    error "invalid spec length"
+	    return -1
+	}
+
+	verbose -log "APB: SPEC: $spec"
+
+	set s [lindex $spec 0]
+	set local_options [lindex $spec 1]
+
+	if { ! [regexp "^/" "$s"] } then {
+	    set s "$srcdir/$subdir/$s"
+	}
+
+	if {[llength $spec] > 2} {
+	    set objfile [lindex $spec 2]
+	} else {
+	    set objfile "${binfile}${i}.o"
+	    incr i
+	}
+
+	if  { [$func "${s}" "${objfile}" object $local_options] != "" } {
+	    untested $testname
+	    return -1
+	}
+
+	lappend objects "$objfile"
+
+	if {[lsearch -exact $local_options "split-dwo"] >= 0} {
+	    # Split out the DWO file.
+	    set dwo_file "[file rootname ${objfile}].dwo"
+
+	    if { [extract_dwo_information $objfile $dwo_file] == -1 } {
+		untested $testname
+		return -1
+	    }
+
+	    if { [strip_dwo_information $objfile] == -1 } {
+		untested $testname
+		return -1
+	    }
+	}
+    }
+
+    verbose -log "APB: OBJECTS = $objects"
+
+    set ret [$func $objects "${binfile}" executable $options]
+    if  { $ret != "" } {
+        untested $testname
+        return -1
+    }
 
     return 0
 }
@@ -329,6 +440,14 @@ namespace eval Dwarf {
     # The address size for debug ranges section.
     variable _debug_ranges_64_bit
 
+    # The index into the .debug_addr section (used for fission
+    # generation).
+    variable _debug_addr_index
+
+    # Flag, true if the current CU is contains fission information,
+    # otherwise false.
+    variable _cu_is_fission
+
     proc _process_one_constant {name value} {
 	variable _constants
 	variable _AT
@@ -486,6 +605,18 @@ namespace eval Dwarf {
 		_op .${_cu_addr_size}byte $value
 	    }
 
+	    DW_FORM_GNU_addr_index {
+		variable _debug_addr_index
+		variable _cu_addr_size
+
+		_op .uleb128 ${_debug_addr_index}
+		incr _debug_addr_index
+
+		_defer_output .debug_addr {
+		    _op .${_cu_addr_size}byte $value
+		}
+	    }
+
 	    DW_FORM_data2 -
 	    DW_FORM_ref2 {
 		_op .2byte $value
@@ -553,7 +684,6 @@ namespace eval Dwarf {
 	    DW_FORM_strx3 -
 	    DW_FORM_strx4 -
 
-	    DW_FORM_GNU_addr_index -
 	    DW_FORM_GNU_str_index -
 
 	    default {
@@ -609,6 +739,9 @@ namespace eval Dwarf {
 	    DW_AT_name {
 		return DW_FORM_string
 	    }
+	    DW_AT_GNU_addr_base {
+		return DW_FORM_sec_offset
+	    }
 	}
 	return ""
     }
@@ -649,6 +782,8 @@ namespace eval Dwarf {
     # Handle macro attribute MACRO_AT_range.
 
     proc _handle_macro_at_range { attr_value } {
+	variable _cu_is_fission
+
 	if {[llength $attr_value] != 1} {
 	    error "usage: MACRO_AT_range { func }"
 	}
@@ -658,10 +793,14 @@ namespace eval Dwarf {
 	set src ${srcdir}/${subdir}/${srcfile}
 	set result [function_range $func $src]
 
-	_handle_attribute DW_AT_low_pc [lindex $result 0] \
-	    DW_FORM_addr
+	set form DW_FORM_addr
+	if { $_cu_is_fission } {
+	    set form DW_FORM_GNU_addr_index
+	}
+
+	_handle_attribute DW_AT_low_pc [lindex $result 0] $form
 	_handle_attribute DW_AT_high_pc \
-	    "[lindex $result 0] + [lindex $result 1]" DW_FORM_addr
+	    "[lindex $result 0] + [lindex $result 1]" $form
     }
 
     # Handle macro attribute MACRO_AT_func.
@@ -945,6 +1084,18 @@ namespace eval Dwarf {
 		    _op .${addr_size}byte $argvec(size)
 		}
 
+		DW_OP_GNU_addr_index {
+		    variable _debug_addr_index
+		    variable _cu_addr_size
+
+		    _op .uleb128 ${_debug_addr_index}
+		    incr _debug_addr_index
+
+		    _defer_output .debug_addr {
+			_op .${_cu_addr_size}byte [lindex $line 1]
+		    }
+		}
+
 		DW_OP_regx {
 		    _get_args $line $opcode register
 		    _op .uleb128 $argvec(register)
@@ -1069,6 +1220,23 @@ namespace eval Dwarf {
 	}
     }
 
+    # Return a label that references the current position in the
+    # .debug_addr table.  When a user is creating split DWARF they
+    # will define two CUs, the first will be the split DWARF content,
+    # and the second will be the non-split stub CU.  The split DWARF
+    # CU fills in the .debug_addr section, but the non-split CU
+    # includes a reference to the start of the section.  The label
+    # returned by this proc provides that reference.
+    proc debug_addr_label {} {
+	variable _debug_addr_index
+
+	set lbl [new_label "debug_addr_idx_${_debug_addr_index}_"]
+	_defer_output .debug_addr {
+	    define_label $lbl
+	}
+	return $lbl
+    }
+
     # Emit a DWARF CU.
     # OPTIONS is a list with an even number of elements containing
     # option-name and option-value pairs.
@@ -1092,12 +1260,13 @@ namespace eval Dwarf {
 	variable _cu_version
 	variable _cu_addr_size
 	variable _cu_offset_size
+	variable _cu_is_fission
 
 	# Establish the defaults.
 	set is_64 0
 	set _cu_version 4
 	set _cu_addr_size default
-	set fission 0
+	set _cu_is_fission 0
 	set section ".debug_info"
 	set _abbrev_section ".debug_abbrev"
 
@@ -1107,7 +1276,7 @@ namespace eval Dwarf {
 		is_64 { set is_64 $value }
 		version { set _cu_version $value }
 		addr_size { set _cu_addr_size $value }
-		fission { set fission $value }
+		fission { set _cu_is_fission $value }
 		default { error "unknown option $name" }
 	    }
 	}
@@ -1119,7 +1288,7 @@ namespace eval Dwarf {
 	    }
 	}
 	set _cu_offset_size [expr { $is_64 ? 8 : 4 }]
-	if { $fission } {
+	if { $_cu_is_fission } {
 	    set section ".debug_info.dwo"
 	    set _abbrev_section ".debug_abbrev.dwo"
 	}
@@ -1199,12 +1368,13 @@ namespace eval Dwarf {
 	variable _cu_version
 	variable _cu_addr_size
 	variable _cu_offset_size
+	variable _cu_is_fission
 
 	# Establish the defaults.
 	set is_64 0
 	set _cu_version 4
 	set _cu_addr_size default
-	set fission 0
+	set _cu_is_fission 0
 	set section ".debug_types"
 	set _abbrev_section ".debug_abbrev"
 
@@ -1213,7 +1383,7 @@ namespace eval Dwarf {
 		is_64 { set is_64 $value }
 		version { set _cu_version $value }
 		addr_size { set _cu_addr_size $value }
-		fission { set fission $value }
+		fission { set _cu_is_fission $value }
 		default { error "unknown option $name" }
 	    }
 	}
@@ -1225,7 +1395,7 @@ namespace eval Dwarf {
 	    }
 	}
 	set _cu_offset_size [expr { $is_64 ? 8 : 4 }]
-	if { $fission } {
+	if { $_cu_is_fission } {
 	    set section ".debug_types.dwo"
 	    set _abbrev_section ".debug_abbrev.dwo"
 	}
@@ -2075,6 +2245,7 @@ namespace eval Dwarf {
 	variable _line_saw_program
 	variable _line_header_end_label
 	variable _debug_ranges_64_bit
+	variable _debug_addr_index
 
 	if {!$_initialized} {
 	    _read_constants
@@ -2093,6 +2264,8 @@ namespace eval Dwarf {
 	set _line_saw_program 0
 	set _debug_ranges_64_bit [is_64_target]
 
+	set _debug_addr_index 0
+
 	# Not "uplevel" here, because we want to evaluate in this
 	# namespace.  This is somewhat bad because it means we can't
 	# readily refer to outer variables.