Re: [PATCH] gdb.dwarf2: Define and use gdb_target_symbol_prefix for symbol prefixes

Kevin Buettner
2015-11-05T20:01:47Z

On Thu, 05 Nov 2015 10:14:09 +0000
Pedro Alves <palves@redhat.com> wrote:

> > Defining the obvious proc (for gdb_target_symbol) worked out of the
> > box for all cases except gdb.dwarf2/atomic-type.exp. For that I
> > needed to make a change to lib/dwarf.exp (and learned a bit more about
> > tcl in the process). If you know of a cleaner way to code it, let me
> > know - I couldn't think of a way to do it without adding the if-else
> > statement.
>
> Not sure I see what makes gdb.dwarf2/atomic-type.exp different?
> E.g., the gdb.dwarf2/dw2-bad-mips-linkage-name.exp hunk looks quite
> similar. What makes gdb.dwarf2/atomic-type.exp special?

I was mistaken. Both of these tests - dw2-bad-mips-linkage-name.exp
and atomic-type.exp - have problems due to the fact that the call to
gdb_target_symbol appears within a DW_TAG_ construct. The proc
_handle_DW_TAG performs command and variable expansion within a DW_TAG_
construct. (It does other things too.)

When I remove my change to dwarf.exp, this what I see in the log
file:

ERROR: tcl error sourcing /ironwood1/sourceware-git/mesquite-native/bld/../../binutils-gdb/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp.
ERROR: missing close-bracket
while executing
"subst {[gdb_target_symbol}"
("uplevel" body line 1)
invoked from within
"uplevel 2 [list subst [lindex $attr 1]]"
(procedure "_handle_DW_TAG" line 31)
invoked from within
"_handle_DW_TAG DW_TAG_subprogram $attrs $children"
(procedure "DW_TAG_subprogram" line 1)
invoked from within
"DW_TAG_subprogram {
{name f}
{low_pc [gdb_target_symbol f] addr}
{high_pc f_end_lbl addr}
..."
("uplevel" body line 9)
invoked from within
"uplevel 2 $children"
(procedure "_handle_DW_TAG" line 61)
invoked from within
"_handle_DW_TAG DW_TAG_compile_unit $attrs $children"
(procedure "DW_TAG_compile_unit" line 1)
invoked from within
"DW_TAG_compile_unit {
{DW_AT_language @DW_LANG_C}
{DW_AT_name dw2-bad-mips-linkage-name.c}
{DW_AT_..."
("uplevel" body line 2)
invoked from within
"uplevel $body"
(procedure "cu" line 66)
invoked from within
"cu {} {
DW_TAG_compile_unit {
{DW_AT_language @DW_LANG_C}
{DW_AT_name dw2-bad-mips-linkage-name.c}
..."
("eval" body line 2)
invoked from within
"eval $body"
(procedure "Dwarf::assemble" line 30)
invoked from within
"Dwarf::assemble $asm_file {
cu {} {
DW_TAG_compile_unit {
{DW_AT_language @DW_LANG_C}
{DW_AT_name dw2-bad-mip..."

The reason for this is that '[gdb_target_symbol' is one list element
and 'f]' is another. The code, as it was originally written, invoked
subst on just a single element. When invoked on (just) '[gdb_target_symbol'
it rightly complains about the "missing close-bracket".

My change joins the list elements together and then invokes subst on
them:

if {[llength $attr] > 2} {
set attr_value [uplevel 2 [list subst [join [lrange $attr 1 end-1]]]]
} else {
set attr_value [uplevel 2 [list subst [lindex $attr 1]]]
}

versus just this line, originally:

set attr_value [uplevel 2 [list subst [lindex $attr 1]]]

I was hoping to write this somewhat more compactly, but we need to
accomodate the case where a form is not provided. The original statement,
in the else clause, still handles this.

Thanks again for your comments.

Kevin

> > diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> > index 048070b..e1c9839 100644
> > --- a/gdb/testsuite/lib/gdb.exp
> > +++ b/gdb/testsuite/lib/gdb.exp
> > @@ -5521,6 +5521,54 @@ proc core_find {binfile {deletefiles {}} {arg ""}} {
> > return $destcore
> > }
> >
> > +# gdb_target_symbol_prefix compiles a test program and uses readelf to
>
> s/readelf/objdump/

Fixed in the new version...

gdb.dwarf2: Define and use gdb_target_symbol for symbol prefixes

Some of the tests in gdb.dwarf2 which use Dwarf::assemble refer to
(minimal/linker) symbols created in the course of building a small
test program. Some targets use a prefix such as underscore ("_") on
these symbols. Many of the tests in gdb.dwarf2 do not take this into
account. As a consequence, these tests fail to build, resulting
either in failures or untested testcases.

Here is an example from gdb.dwarf2/dw2-regno-invalid.exp:

Dwarf::assemble $asm_file {
cu {} {
compile_unit {
{low_pc main DW_FORM_addr}
{high_pc main+0x10000 DW_FORM_addr}
} {
...
}

For targets which require an underscore prefix on linker symbols,
the two occurrences of "main" would have to have a prepended underscore,
i.e. _main instead of main.

For the above case, a call to the new proc gdb_target_symbol is used
prepend the correct prefix to the symbol. I.e. the above code is
rewritten (as shown in the patch) as follows:

Dwarf::assemble $asm_file {
cu {} {
compile_unit {
{low_pc [gdb_target_symbol main] DW_FORM_addr}
{high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr}
} {
...
}

I also found it necessary to make an adjustment to lib/dwarf.exp so that
expressions of more than just one list element can be used in DW_TAG_...
constructs. Both atomic-type.exp and dw2-bad-mips-linkage-name.exp require
this new functionality.

gdb/testsuite/ChangeLog:

* lib/gdb.exp (gdb_target_symbol_prefix, gdb_target_symbol):
New procs.
* lib/dwarf.exp (_handle_DW_TAG): Handle attribute values,
representing expressions, of more than one list element.
* gdb.dwarf2/atomic-type.exp (Dwarf::assemble): Use gdb_target_symbol
to prepend linker symbol prefix to f.
* gdb.dwarf2/data-loc.exp (Dwarf::assemble): Likewise, for
table_1 and table_2.
* gdb.dwarf2/dw2-bad-mips-linkage-name.exp (Dwarf::assemble):
Likewise, for f and g.
* gdb.dwarf2/dw2-ifort-parameter.exp (Dwarf::assemble): Likewise,
for ptr.
* gdb.dwarf2/dw2-regno-invalid.exp (Dwarf::assemble): Likewise,
for main.
* gdb.dwarf2/dynarr-ptr.exp (Dwarf::assemble): Likewise, for
table_1_ptr and table_2_ptr.
---
gdb/testsuite/gdb.dwarf2/atomic-type.exp | 2 +-
gdb/testsuite/gdb.dwarf2/data-loc.exp | 8 ++--
.../gdb.dwarf2/dw2-bad-mips-linkage-name.exp | 4 +-
gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.exp | 2 +-
gdb/testsuite/gdb.dwarf2/dw2-regno-invalid.exp | 8 ++--
gdb/testsuite/gdb.dwarf2/dynarr-ptr.exp | 8 ++--
gdb/testsuite/lib/dwarf.exp | 15 ++++++-
gdb/testsuite/lib/gdb.exp | 48 ++++++++++++++++++++++
8 files changed, 77 insertions(+), 18 deletions(-)

diff --git a/gdb/testsuite/gdb.dwarf2/atomic-type.exp b/gdb/testsuite/gdb.dwarf2/atomic-type.exp
index fb315e3..e2a3447 100644
--- a/gdb/testsuite/gdb.dwarf2/atomic-type.exp
+++ b/gdb/testsuite/gdb.dwarf2/atomic-type.exp
@@ -68,7 +68,7 @@ Dwarf::assemble $asm_file {

DW_TAG_subprogram {
{name f}
- {low_pc f addr}
+ {low_pc [gdb_target_symbol f] addr}
{high_pc f_end_lbl addr}
{type :$i_l}
} {
diff --git a/gdb/testsuite/gdb.dwarf2/data-loc.exp b/gdb/testsuite/gdb.dwarf2/data-loc.exp
index e9e702c..a1fb772 100644
--- a/gdb/testsuite/gdb.dwarf2/data-loc.exp
+++ b/gdb/testsuite/gdb.dwarf2/data-loc.exp
@@ -84,7 +84,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__three}
{DW_AT_type :$array_label}
{DW_AT_location {
- DW_OP_addr table_1
+ DW_OP_addr [gdb_target_symbol table_1]
} SPECIAL_expr}
{external 1 flag}
}
@@ -92,7 +92,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__three_tdef}
{DW_AT_type :$array_ptr_label}
{DW_AT_location {
- DW_OP_addr table_1
+ DW_OP_addr [gdb_target_symbol table_1]
} SPECIAL_expr}
{external 1 flag}
}
@@ -100,7 +100,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__five}
{DW_AT_type :$array_label}
{DW_AT_location {
- DW_OP_addr table_2
+ DW_OP_addr [gdb_target_symbol table_2]
} SPECIAL_expr}
{external 1 flag}
}
@@ -108,7 +108,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__five_tdef}
{DW_AT_type :$array_ptr_label}
{DW_AT_location {
- DW_OP_addr table_2
+ DW_OP_addr [gdb_target_symbol table_2]
} SPECIAL_expr}
{external 1 flag}
}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp b/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp
index 77f6175..dfb9567 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp
@@ -42,14 +42,14 @@ Dwarf::assemble $asm_file {
}
DW_TAG_subprogram {
{name f}
- {low_pc f addr}
+ {low_pc [gdb_target_symbol f] addr}
{high_pc f_end_lbl addr}
{type :$b_l}
{DW_AT_MIPS_linkage_name _Z1fv}
}
DW_TAG_subprogram {
{name g}
- {low_pc g addr}
+ {low_pc [gdb_target_symbol g] addr}
{high_pc g_end_lbl addr}
{type :$b_l}
{DW_AT_MIPS_linkage_name 42 DW_FORM_data1}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.exp b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.exp
index c71103d..4f07b50 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.exp
@@ -53,7 +53,7 @@ Dwarf::assemble $asm_file {
{variable_parameter 1 flag}
{type :$int_label}
{location {
- addr ptr
+ addr [gdb_target_symbol ptr]
deref
} SPECIAL_expr}
}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-regno-invalid.exp b/gdb/testsuite/gdb.dwarf2/dw2-regno-invalid.exp
index a7d77c5..53897bd 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-regno-invalid.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-regno-invalid.exp
@@ -29,8 +29,8 @@ set asm_file [standard_output_file $srcfile]
Dwarf::assemble $asm_file {
cu {} {
compile_unit {
- {low_pc main DW_FORM_addr}
- {high_pc main+0x10000 DW_FORM_addr}
+ {low_pc [gdb_target_symbol main] DW_FORM_addr}
+ {high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr}
} {
declare_labels integer_label

@@ -43,8 +43,8 @@ Dwarf::assemble $asm_file {
DW_TAG_subprogram {
{name main}
{DW_AT_external 1 flag}
- {low_pc main DW_FORM_addr}
- {high_pc main+0x10000 DW_FORM_addr}
+ {low_pc [gdb_target_symbol main] DW_FORM_addr}
+ {high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr}
} {
DW_TAG_variable {
{DW_AT_name bregx}
diff --git a/gdb/testsuite/gdb.dwarf2/dynarr-ptr.exp b/gdb/testsuite/gdb.dwarf2/dynarr-ptr.exp
index 3dcb3d7..0a612fe 100644
--- a/gdb/testsuite/gdb.dwarf2/dynarr-ptr.exp
+++ b/gdb/testsuite/gdb.dwarf2/dynarr-ptr.exp
@@ -85,7 +85,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__three_ptr}
{DW_AT_type :$array_ptr_label}
{DW_AT_location {
- DW_OP_addr table_1_ptr
+ DW_OP_addr [gdb_target_symbol table_1_ptr]
} SPECIAL_expr}
{external 1 flag}
}
@@ -93,7 +93,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__three_ptr_tdef}
{DW_AT_type :$array_typedef_label}
{DW_AT_location {
- DW_OP_addr table_1_ptr
+ DW_OP_addr [gdb_target_symbol table_1_ptr]
} SPECIAL_expr}
{external 1 flag}
}
@@ -101,7 +101,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__five_ptr}
{DW_AT_type :$array_ptr_label}
{DW_AT_location {
- DW_OP_addr table_2_ptr
+ DW_OP_addr [gdb_target_symbol table_2_ptr]
} SPECIAL_expr}
{external 1 flag}
}
@@ -109,7 +109,7 @@ Dwarf::assemble $asm_file {
{DW_AT_name foo__five_ptr_tdef}
{DW_AT_type :$array_typedef_label}
{DW_AT_location {
- DW_OP_addr table_2_ptr
+ DW_OP_addr [gdb_target_symbol table_2_ptr]
} SPECIAL_expr}
{external 1 flag}
}
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 888ba94..383f8f5 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -621,7 +621,18 @@ namespace eval Dwarf {

foreach attr $attrs {
set attr_name [_map_name [lindex $attr 0] _AT]
- set attr_value [uplevel 2 [list subst [lindex $attr 1]]]
+
+ # When the length of ATTR is greater than 2, the last
+ # element of the list must be a form. The second through
+ # the penultimate elements are joined together and
+ # evaluated using subst. This allows constructs such as
+ # [gdb_target_symbol foo] to be used.
+
+ if {[llength $attr] > 2} {
+ set attr_value [uplevel 2 [list subst [join [lrange $attr 1 end-1]]]]
+ } else {
+ set attr_value [uplevel 2 [list subst [lindex $attr 1]]]
+ }

if { [string equal "MACRO_AT_func" $attr_name] } {
_handle_macro_at_func $attr_value
@@ -629,7 +640,7 @@ namespace eval Dwarf {
_handle_macro_at_range $attr_value
} else {
if {[llength $attr] > 2} {
- set attr_form [lindex $attr 2]
+ set attr_form [lindex $attr end]
} else {
# If the value looks like an integer, a form is required.
if [string is integer $attr_value] {
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 048070b..f11609b 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5521,6 +5521,54 @@ proc core_find {binfile {deletefiles {}} {arg ""}} {
return $destcore
}

+# gdb_target_symbol_prefix compiles a test program and then examines
+# the output from objdump to determine the prefix (such as underscore)
+# for linker symbol prefixes.
+
+gdb_caching_proc gdb_target_symbol_prefix {
+ # Set up and compile a simple test program...
+ set src [standard_temp_file main[pid].c]
+ set exe [standard_temp_file main[pid].x]
+
+ gdb_produce_source $src {
+ int main() {
+ return 0;
+ }
+ }
+
+ verbose "compiling testfile $src" 2
+ set compile_flags {debug nowarnings quiet}
+ set lines [gdb_compile $src $exe executable $compile_flags]
+
+ set prefix ""
+
+ if ![string match "" $lines] then {
+ verbose "gdb_target_symbol_prefix: testfile compilation failed, returning null prefix" 2
+ } else {
+ set objdump_program [gdb_find_objdump]
+ set result [catch "exec $objdump_program --syms $exe" output]
+
+ if { $result == 0 \
+ && ![regexp -lineanchor \
+ { ([^ a-zA-Z0-9]*)main$} $output dummy prefix] } {
+ verbose "gdb_target_symbol_prefix: Could not find main in objdump output; returning null prefix" 2
+ }
+ }
+
+ file delete $src
+ file delete $exe
+
+ return $prefix
+}
+
+# gdb_target_symbol returns the provided symbol with the correct prefix
+# prepended. (See gdb_target_symbol_prefix, above.)
+
+proc gdb_target_symbol { symbol } {
+ set prefix [gdb_target_symbol_prefix]
+ return "${prefix}${symbol}"
+}
+
# gdb_target_symbol_prefix_flags returns a string that can be added
# to gdb_compile options to define SYMBOL_PREFIX macro value
# symbol_prefix_flags returns a string that can be added