Use dwarf assembler in gdb.dwarf2/implptr-64bit.exp

This patch adds a DW_OP_implicit_value in dwarf assembler, and uses
dwarf assembler in implptr-64bit.exp.  Using dwarf assembler in
implptr-64bit.exp exposes some limitations in dwarf assembler,

 - some variables are not evaluated in the caller's context, so we
   can not pass variable to assembler, like this

       Dwarf::assemble $asm_file {

	cu {
	    version $dwarf_version
	    addr_size $addr_size
	    is_64 $is_64
	} {
	}

	and

	{DW_AT_type :$struct_label "DW_FORM_ref$ref_addr_size"}

   this limitation is fixed by adding "uplevel" and "subst".

 - dwarf assembler doesn't emit DW_FORM_ref_addr for label referencing.
   this limitation is fixed by adding a new character "%",

	{ type %$int_label }

   this means we want to emit DW_FORM_ref_addr for label referencing.

 - we can't set the form of label referencing offset in dwarf assembler.
   Nowadays, dwarf assembler guesses the form of labels, which is
   DW_FORM_ref4.  However, in implptr-64bit.exp, both DW_FORM_ref4
   and DW_FORM_ref8 is used (see REF_ADDR in implptr-64bit.S).  This
   patch adds the flexibility of setting the form of label reference.
   Both of them below are valid,

	{DW_AT_type :$struct_label}
	{DW_AT_type :$struct_label DW_FORM_ref8}

   the former form is the default DW_FORM_ref4.

I compared the .debug_info of objects without and with this patch
applied.  There is no changes except abbrev numbers.

gdb/testsuite:

2017-01-25  Andreas Arnez  <arnez@linux.vnet.ibm.com>
	    Yao Qi  <yao.qi@linaro.org>

	* gdb.dwarf2/implptr-64bit.exp: Use dwarf assembler.
	* gdb.dwarf2/implptr-64bit.S: Remove.
	* lib/dwarf.exp (Dwarf): Handle character "%".  Evaluate some
	variables in caller's context.  Add DW_OP_implicit_value.

4 files changed, 154 insertions, 236 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index aa272e3..28e337a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2017-01-25  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+	    Yao Qi  <yao.qi@linaro.org>
+
+	* gdb.dwarf2/implptr-64bit.exp: Use dwarf assembler.
+	* gdb.dwarf2/implptr-64bit.S: Remove.
+	* lib/dwarf.exp (Dwarf): Handle character "%".  Evaluate some
+	variables in caller's context.  Add DW_OP_implicit_value.
+
 2017-01-25  Yao Qi  <yao.qi@linaro.org>
 
 	* lib/dwarf.exp (Dwarf::_location): Handle
diff --git a/gdb/testsuite/gdb.dwarf2/implptr-64bit.S b/gdb/testsuite/gdb.dwarf2/implptr-64bit.S
deleted file mode 100644
index 003bf20..0000000
--- a/gdb/testsuite/gdb.dwarf2/implptr-64bit.S
+++ /dev/null
@@ -1,226 +0,0 @@
-/* Copyright 2010-2017 Free Software Foundation, Inc.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-	.section	.debug_info
-d:
-	/* Length of Compilation Unit Info */
-#if OFFSET_SIZE == 4
-# define OFFSET .4byte
-# define HEADER_LINE1
-# define HEADER_LINE2(END) .4byte	END - 1f
-#elif OFFSET_SIZE == 8
-# define OFFSET .8byte
-# define HEADER_LINE1 .4byte	0xffffffff
-# define HEADER_LINE2(END) .8byte	END - 1f
-#else
-# error
-#endif
-#if ADDR_SIZE == 4
-# define ADDR .4byte
-#elif ADDR_SIZE == 8
-# define ADDR .8byte
-#else
-# error
-#endif
-#if REF_ADDR_SIZE == 4
-# define REF_ADDR .4byte
-#elif REF_ADDR_SIZE == 8
-# define REF_ADDR .8byte
-#else
-# error
-#endif
-	
-#if TWO_CU
-# define END1 .Lcu_end_1
-#else
-# define END1 debug_end
-#endif
-
-	HEADER_LINE1
-	HEADER_LINE2(END1)
-
-1:
-	.2byte	DWARF_VERSION	/* DWARF version number */
-	OFFSET	.Ldebug_abbrev0	/* Offset Into Abbrev. Section */
-	.byte	ADDR_SIZE	/* Pointer Size (in bytes) */
-
-	.uleb128 0x1	/* (DIE (0xb) DW_TAG_compile_unit) */
-	.ascii "GNU C 4.4.3\0"	/* DW_AT_producer */
-	.byte	0x1	/* DW_AT_language */
-	.ascii "1.c\0"	/* DW_AT_name */
-
-.Ltype_int:
-	.uleb128 0x7	/* DW_TAG_base_type */
-	.byte	0x4	/* DW_AT_byte_size */
-	.byte	0x5	/* DW_AT_encoding */
-	.ascii "int\0"	/* DW_AT_name */
-
-.Ltype_struct:
-	.uleb128 0x2	/* DW_TAG_structure_type */
-	.ascii "s\0"	/* DW_AT_name */
-	.byte	4	/* DW_AT_byte_size */
-
-	.uleb128 0x3	/* DW_TAG_member */
-	.ascii "f\0"	/* DW_AT_name */
-	.4byte	.Ltype_int - d	/* DW_AT_type */
-	.byte	0	/* DW_AT_data_member_location */
-
-	.byte	0x0	/* end of children of DW_TAG_structure_type */
-
-.Ltype_structptr:
-	.uleb128 0x5	/* DW_TAG_pointer_type */
-	.byte	ADDR_SIZE	/* DW_AT_byte_size */
-	.4byte	.Ltype_struct - d	/* DW_AT_type */
-
-.Lvar_out:
-	.uleb128 0x4	/* (DW_TAG_variable) */
-	.ascii "v\0"	/* DW_AT_name */
-	.byte	2f - 1f	/* DW_AT_location: DW_FORM_block1 */
-1:
-	.byte	0x9e	/* DW_OP_implicit_value */
-	.uleb128  2f - 3f
-3:
-	.byte	1, 1, 1, 1
-2:
-	REF_ADDR	.Ltype_struct - d	/* DW_AT_type */
-
-#if TWO_CU
-	.byte	0x0	/* end of children of CU */
-.Lcu_end_1:
-
-	HEADER_LINE1
-	HEADER_LINE2 (debug_end)
-
-1:
-	.2byte	DWARF_VERSION	/* DWARF version number */
-	OFFSET	.Ldebug_abbrev0	/* Offset Into Abbrev. Section */
-	.byte	ADDR_SIZE	/* Pointer Size (in bytes) */
-
-	.uleb128 0x1	/* (DIE (0xb) DW_TAG_compile_unit) */
-	.ascii "GNU C 4.4.3\0"	/* DW_AT_producer */
-	.byte	0x1	/* DW_AT_language */
-	.ascii "1.c\0"	/* DW_AT_name */
-#endif
-
-	.uleb128	6			/* Abbrev: DW_TAG_subprogram */
-	.ascii		"main\0"		/* DW_AT_name */
-	ADDR		main			/* DW_AT_low_pc */
-	ADDR		main + 0x100		/* DW_AT_high_pc */
-	REF_ADDR	.Ltype_int - d		/* DW_AT_type */
-	.byte		1			/* DW_AT_external */
-
-	.uleb128 0x4	/* (DW_TAG_variable) */
-	.ascii "p\0"	/* DW_AT_name */
-	.byte	2f - 1f	/* DW_AT_location: DW_FORM_block1 */
-1:
-	.byte	0xf2	/* DW_OP_GNU_implicit_pointer */
-	REF_ADDR	.Lvar_out - d	/* referenced DIE */
-	.sleb128	0	/* offset */
-2:
-	REF_ADDR	.Ltype_structptr - d	/* DW_AT_type */
-
-	.byte	0x0	/* end of children of main */
-
-	.byte	0x0	/* end of children of CU */
-debug_end:
-
-	.section	.debug_abbrev
-.Ldebug_abbrev0:
-
-	.uleb128 0x1	/* (abbrev code) */
-	.uleb128 0x11	/* (TAG: DW_TAG_compile_unit) */
-	.byte	0x1	/* DW_children_yes */
-	.uleb128 0x25	/* (DW_AT_producer) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.uleb128 0x13	/* (DW_AT_language) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.uleb128 0x3	/* (DW_AT_name) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.byte	0x0
-	.byte	0x0
-
-	.uleb128 0x2	/* (abbrev code) */
-	.uleb128 0x13	/* (TAG: DW_TAG_structure_type) */
-	.byte	0x1	/* DW_children_yes */
-	.uleb128 0x3	/* (DW_AT_name) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.uleb128 0xb	/* (DW_AT_byte_size) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.byte	0
-	.byte	0
-
-	.uleb128 0x3	/* (abbrev code) */
-	.uleb128 0xd	/* (TAG: DW_TAG_member) */
-	.byte	0	/* DW_children_no */
-	.uleb128 0x3	/* (DW_AT_name) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.uleb128 0x49	/* (DW_AT_type) */
-	.uleb128 0x13	/* (DW_FORM_ref4) */
-	.uleb128 0x38	/* (DW_AT_data_member_location) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.byte	0
-	.byte	0
-
-	.uleb128 0x4	/* (abbrev code) */
-	.uleb128 0x34	/* (TAG: DW_TAG_variable) */
-	.byte	0x0	/* DW_children_yes */
-	.uleb128 0x3	/* (DW_AT_name) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.uleb128 0x02	/* (DW_AT_location) */
-	.uleb128 0xa	/* (DW_FORM_block1) */
-	.uleb128 0x49	/* (DW_AT_type) */
-	.uleb128 0x10	/* (DW_FORM_ref_addr) */
-	.byte	0x0
-	.byte	0x0
-
-	.uleb128 0x5	/* (abbrev code) */
-	.uleb128 0xf	/* (TAG: DW_TAG_pointer_type) */
-	.byte	0x0	/* DW_children_no */
-	.uleb128 0xb	/* (DW_AT_byte_size) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.uleb128 0x49	/* (DW_AT_type) */
-	.uleb128 0x13	/* (DW_FORM_ref4) */
-	.byte	0x0
-	.byte	0x0
-
-	.uleb128	6			/* Abbrev code */
-	.uleb128	0x2e			/* DW_TAG_subprogram */
-	.byte		1			/* has_children */
-	.uleb128	0x3			/* DW_AT_name */
-	.uleb128	0x8			/* DW_FORM_string */
-	.uleb128	0x11			/* DW_AT_low_pc */
-	.uleb128	0x1			/* DW_FORM_addr */
-	.uleb128	0x12			/* DW_AT_high_pc */
-	.uleb128	0x1			/* DW_FORM_addr */
-	.uleb128	0x49			/* DW_AT_type */
-	.uleb128	0x10			/* DW_FORM_ref_addr */
-	.uleb128	0x3f			/* DW_AT_external */
-	.uleb128	0xc			/* DW_FORM_flag */
-	.byte		0x0			/* Terminator */
-	.byte		0x0			/* Terminator */
-
-	.uleb128 0x7	/* (abbrev code) */
-	.uleb128 0x24	/* (TAG: DW_TAG_base_type) */
-	.byte	0	/* DW_children_no */
-	.uleb128 0xb	/* (DW_AT_byte_size) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.uleb128 0x3e	/* (DW_AT_encoding) */
-	.uleb128 0xb	/* (DW_FORM_data1) */
-	.uleb128 0x3	/* (DW_AT_name) */
-	.uleb128 0x8	/* (DW_FORM_string) */
-	.byte	0
-	.byte	0
-
-	.byte	0x0
diff --git a/gdb/testsuite/gdb.dwarf2/implptr-64bit.exp b/gdb/testsuite/gdb.dwarf2/implptr-64bit.exp
index b4dcbde..963cdc6 100644
--- a/gdb/testsuite/gdb.dwarf2/implptr-64bit.exp
+++ b/gdb/testsuite/gdb.dwarf2/implptr-64bit.exp
@@ -19,21 +19,121 @@ if {![dwarf2_support]} {
     return 0  
 }
 
-standard_testfile .S
-set mainfile main.c
+standard_testfile main.c
 
 proc test { dwarf_version offset_size addr_size ref_addr_size two_cu } {
-    global testfile srcfile mainfile
+    global testfile srcfile
 
-    # 32-bit targets do not support any of the testcases; keep quiet there.
-    set opts {quiet}
-    foreach n { dwarf_version offset_size addr_size ref_addr_size two_cu } {
-	lappend opts "additional_flags=-D[string toupper $n]=[expr "\$$n"]"
+    set name "d${dwarf_version}o${offset_size}a${addr_size}r${ref_addr_size}t${two_cu}"
+
+    # Make some DWARF for the test.
+    set asm_file [standard_output_file ${testfile}-${name}.S]
+    Dwarf::assemble $asm_file {
+	upvar dwarf_version dwarf_version
+	upvar addr_size addr_size
+	upvar offset_size offset_size
+	upvar ref_addr_size ref_addr_size
+	upvar two_cu two_cu
+
+	set is_64 [expr { $offset_size == 4 ? 0 : 1 }]
+
+	cu {
+	    version $dwarf_version
+	    addr_size $addr_size
+	    is_64 $is_64
+	} {
+	    compile_unit {
+		{ producer "GNU C 4.4.3" }
+		{ language @DW_LANG_C89 }
+		{ name 1.c }
+	    } {
+		declare_labels struct_label variable_label int_label pointer_label
+
+		int_label: base_type {
+		    { byte_size 4 DW_FORM_sdata }
+		    { DW_AT_encoding @DW_ATE_signed }
+		    { name int }
+		}
+
+		struct_label: structure_type {
+		    { name s }
+		    { byte_size 4 sdata }
+		} {
+		    member {
+			{ name f }
+			{ type :$int_label }
+			{ data_member_location 0 data1 }
+		    }
+		}
+
+		pointer_label: pointer_type {
+		    { byte_size $Dwarf::_cu_addr_size sdata }
+		    { type  :$struct_label }
+		}
+
+		variable_label: DW_TAG_variable {
+		    { name v }
+		    { location {
+			DW_OP_implicit_value 0x1 0x1 0x1 0x1
+		    } SPECIAL_expr}
+		    { type :$struct_label "DW_FORM_ref$ref_addr_size" }
+		}
+
+		if { !$two_cu } {
+		    subprogram {
+			{ name main }
+			{ low_pc main addr }
+			{ high_pc "main+0x100" addr }
+			{ type %$int_label }
+			{ external 1 flag }
+		    } {
+			DW_TAG_variable {
+			    { name p }
+			    { location {
+				GNU_implicit_pointer $variable_label 0
+			    } SPECIAL_expr }
+			    { type :$pointer_label "DW_FORM_ref$ref_addr_size" }
+			}
+		    }
+		}
+	    }
+	}
+
+	if { $two_cu } {
+	    cu {
+		version $dwarf_version
+		addr_size $addr_size
+		is_64 $is_64
+	    } {
+		compile_unit {
+		    { producer "GNU C 4.4.3" }
+		    { language @DW_LANG_C89 }
+		    { name 1.c }
+		} {
+		    subprogram {
+			{ name main }
+			{ low_pc main addr }
+			{ high_pc "main+0x100" addr }
+			{ type %$int_label }
+			{ external 1 flag }
+		    } {
+			DW_TAG_variable {
+			    { name p }
+			    { location {
+				GNU_implicit_pointer $variable_label 0
+			    } SPECIAL_expr }
+			    { type %$pointer_label }
+			}
+		    }
+		}
+	    }
+	}
     }
 
-    set name "d${dwarf_version}o${offset_size}a${addr_size}r${ref_addr_size}t${two_cu}"
+    # 32-bit targets do not support any of the testcases; keep quiet there.
+    set opts {quiet}
     set executable ${testfile}-${name}
-    if [prepare_for_testing "failed to prepare" $executable "${srcfile} ${mainfile}" $opts] {
+    if [prepare_for_testing "failed to prepare" $executable "${asm_file} ${srcfile}" $opts] {
 	return -1
     }
 
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 03ae637..149038c 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -229,6 +229,8 @@ proc function_range { func src } {
 # * If VALUE starts with the ":" character, then it is a label
 #   reference.  The rest of VALUE is taken to be the name of a label,
 #   and DW_FORM_ref4 is used.  See 'new_label' and 'define_label'.
+# * If VALUE starts with the "%" character, then it is a label
+#   reference too, but DW_FORM_ref_addr is used.
 # * Otherwise, VALUE is taken to be a string and DW_FORM_string is
 #   used.  In order to prevent bugs where a numeric value is given but
 #   no form is specified, it is an error if the value looks like a number
@@ -554,6 +556,15 @@ namespace eval Dwarf {
 		return DW_FORM_ref4
 	    }
 
+	    % {
+		# Label reference, an offset from .debug_info.  Assuming
+		# .Lcu1_begin is on .debug_info.
+		set cu1_label [_compute_label "cu1_begin"]
+		set new_value "[string range $value 1 end] - $cu1_label"
+
+		return DW_FORM_ref_addr
+	    }
+
 	    default {
 		return DW_FORM_string
 	    }
@@ -649,7 +660,12 @@ namespace eval Dwarf {
 		_handle_macro_at_range $attr_value
 	    } else {
 		if {[llength $attr] > 2} {
-		    set attr_form [lindex $attr end]
+		    set attr_form [uplevel 2 [list subst [lindex $attr end]]]
+
+		    if { [string index $attr_value 0] == ":" } {
+			# It is a label, get its value.
+			_guess_form $attr_value attr_value
+		    }
 		} else {
 		    # If the value looks like an integer, a form is required.
 		    if [string is integer $attr_value] {
@@ -907,6 +923,25 @@ namespace eval Dwarf {
 		    _op .2byte [lindex $line 1]
 		}
 
+		DW_OP_implicit_value {
+		    set l1 [new_label "value_start"]
+		    set l2 [new_label "value_end"]
+		    _op .uleb128 "$l2 - $l1"
+		    define_label $l1
+		    foreach value [lrange $line 1 end] {
+			switch -regexp -- $value {
+			    {^0x[[:xdigit:]]{1,2}$} {_op .byte $value}
+			    {^0x[[:xdigit:]]{4}$} {_op .2byte $value}
+			    {^0x[[:xdigit:]]{8}$} {_op .4byte $value}
+			    {^0x[[:xdigit:]]{16}$} {_op .8byte $value}
+			    default {
+				error "bad value '$value' in DW_OP_implicit_value"
+			    }
+			}
+		    }
+		    define_label $l2
+		}
+
 		DW_OP_GNU_implicit_pointer {
 		    if {[llength $line] != 3} {
 			error "usage: DW_OP_GNU_implicit_pointer LABEL OFFSET"
@@ -976,6 +1011,7 @@ namespace eval Dwarf {
 	set _abbrev_section ".debug_abbrev"
 
 	foreach { name value } $options {
+	    set value [uplevel 1 "subst \"$value\""]
 	    switch -exact -- $name {
 		is_64 { set is_64 $value }
 		version { set _cu_version $value }