[2/6] DW attribute macro MACRO_AT_func and MACRO_AT_range
Commit Message
Doug Evans <dje@google.com> writes:
>>> IWBN if one could add new macros simply by writing a new function.
>>>
>>> Can _handle_macro_attribute be rewritten such that
>>> MACRO_AT_{func,range} are themselves functions?
>>
>> I don't see any difficulties to implement MACRO_AT_{func,range} as
>> functions here, but could you tell me why do you prefer to do that?
>> Is it because they are macros?
>
> I was thinking long term I'd rather maintain the individual functions
> instead of one large switch statement, all else being equal, and if I
> have the choice.
OK, that is fine. I add two procedures for MACROS_AT_{func,range}
respectively in the updated patch below. As a result,
_handle_macro_attribute is no longer needed, so I remove it from the
updated patch too.
>> + file delete $exe
>> +
>> + return [list "${func}_label - $func_label_offset" $func_length]
>> +}
>> +
> In the immortal words of Shrek, "Hold the phone." ...
> "file delete $exe" is a local operation.
> While in general we don't delete test artifacts,
> I'm left wondering if something about this won't
> work with remote host testing.
> Is that true? Or can "file delete $exe" just be deleted?
I am inclined to delete them via "remote_file host delete" as many
executables func_addr[pid].x are generated. Supposing dwarf assembler
works perfectly, people have only to concentrate on their test artifacts
instead of func_addr[pid].x.
Comments
On Sun, Nov 9, 2014 at 6:04 PM, Yao Qi <yao@codesourcery.com> wrote:
> I am inclined to delete them via "remote_file host delete" as many
> executables func_addr[pid].x are generated. Supposing dwarf assembler
> works perfectly, people have only to concentrate on their test artifacts
> instead of func_addr[pid].x.
OTOH, leaving such things around for debug purposes is important,
or at least not making it difficult to keep such things (and editing source
files to, e.g., comment out the "file delete", crosses a threshold of
annoyance for me).
I think the simplicity of implementation and assistance to debugability
of just leaving the file there outweighs the extra code and any perceived
increase in cleanliness.
Plus the more remote file operations we add the more we slow
things down. There's a *ton* of files we leave behind,
I wouldn't worry about leaving a few more behind.
If there were another reason then that might be something
to consider.
[At least with gcc there is -save-temps. We *could* have something
like that here, but I'm ok with just leaving them.]
@@ -86,6 +86,81 @@ proc build_executable_from_fission_assembler { testname executable sources optio
return 0
}
+# Return a list of expressions about function FUNC's address and length.
+# The first expression is the address of function FUNC, and the second
+# one is FUNC's length. SRC is the source file having function FUNC.
+# An internal label ${func}_label must be defined inside FUNC:
+#
+# int main (void)
+# {
+# asm ("main_label: .globl main_label");
+# return 0;
+# }
+#
+# This label is needed to compute the start address of function FUNC.
+# If the compiler is gcc, we can do the following to get function start
+# and end address too:
+#
+# asm ("func_start: .globl func_start");
+# static void func (void) {}
+# asm ("func_end: .globl func_end");
+#
+# however, this isn't portable, because other compilers, such as clang,
+# may not guarantee the order of global asms and function. The code
+# becomes:
+#
+# asm ("func_start: .globl func_start");
+# asm ("func_end: .globl func_end");
+# static void func (void) {}
+#
+
+proc function_range { func src } {
+ global decimal gdb_prompt
+
+ set exe [standard_temp_file func_addr[pid].x]
+
+ gdb_compile $src $exe executable {debug}
+
+ gdb_exit
+ gdb_start
+ gdb_load "$exe"
+
+ # Compute the label offset, and we can get the function start address
+ # by "${func}_label - $func_label_offset".
+ set func_label_offset ""
+ set test "p ${func}_label - ${func}"
+ gdb_test_multiple $test $test {
+ -re ".* = ($decimal)\r\n$gdb_prompt $" {
+ set func_label_offset $expect_out(1,string)
+ }
+ }
+
+ # Compute the function length.
+ global hex
+ set func_length ""
+ set test "disassemble $func"
+ gdb_test_multiple $test $test {
+ -re ".*$hex <\\+($decimal)>:\[^\r\n\]+\r\nEnd of assembler dump\.\r\n$gdb_prompt $" {
+ set func_length $expect_out(1,string)
+ }
+ }
+
+ # Compute the size of the last instruction.
+ set test "x/2i $func+$func_length"
+ gdb_test_multiple $test $test {
+ -re ".*($hex) <$func\\+$func_length>:\[^\r\n\]+\r\n\[ \]+($hex).*\.\r\n$gdb_prompt $" {
+ set start $expect_out(1,string)
+ set end $expect_out(2,string)
+
+ set func_length [expr $func_length + $end - $start]
+ }
+ }
+
+ remote_file host delete $exe
+
+ return [list "${func}_label - $func_label_offset" $func_length]
+}
+
# A DWARF assembler.
#
# All the variables in this namespace are private to the
@@ -121,6 +196,17 @@ proc build_executable_from_fission_assembler { testname executable sources optio
# This can either be the full name, like 'DW_AT_name', or a shortened
# name, like 'name'. These are fully equivalent.
#
+# Besides DWARF standard attributes, assembler supports 'macro' attribute
+# which will be substituted by one or more standard or macro attributes.
+# supported macro attributes are:
+#
+# - MACRO_AT_range { FUNC FILE }
+# It is substituted by DW_AT_low_pc and DW_AT_high_pc with the start and
+# end address of function FUNC in file FILE.
+#
+# - MACRO_AT_func { FUNC FILE }
+# It is substituted by DW_AT_name with FUNC and MACRO_AT_range.
+#
# If FORM is given, it should name a DW_FORM_ constant.
# This can either be the short form, like 'DW_FORM_addr', or a
# shortened version, like 'addr'. If the form is given, VALUE
@@ -473,6 +559,33 @@ namespace eval Dwarf {
}
}
+ # Handle macro attribute MACRO_AT_range.
+
+ proc _handle_macro_at_range { attr_value } {
+ if {[llength $attr_value] != 2} {
+ error "usage: MACRO_AT_range { func file }"
+ }
+
+ set func [lindex $attr_value 0]
+ set src [lindex $attr_value 1]
+ set result [function_range $func $src]
+
+ _handle_attribute DW_AT_low_pc [lindex $result 0] \
+ DW_FORM_addr
+ _handle_attribute DW_AT_high_pc \
+ "[lindex $result 0] + [lindex $result 1]" DW_FORM_addr
+ }
+
+ # Handle macro attribute MACRO_AT_func.
+
+ proc _handle_macro_at_func { attr_value } {
+ if {[llength $attr_value] != 2} {
+ error "usage: MACRO_AT_func { func file }"
+ }
+ _handle_attribute DW_AT_name [lindex $attr_value 0] DW_FORM_string
+ _handle_macro_at_range $attr_value
+ }
+
proc _handle_DW_TAG {tag_name {attrs {}} {children {}}} {
variable _abbrev_section
variable _abbrev_num
@@ -494,14 +607,21 @@ 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]]]
- if {[llength $attr] > 2} {
- set attr_form [lindex $attr 2]
+
+ if { [string equal "MACRO_AT_func" $attr_name] } {
+ _handle_macro_at_func $attr_value
+ } elseif { [string equal "MACRO_AT_range" $attr_name] } {
+ _handle_macro_at_range $attr_value
} else {
- set attr_form [_guess_form $attr_value attr_value]
- }
- set attr_form [_map_name $attr_form _FORM]
+ if {[llength $attr] > 2} {
+ set attr_form [lindex $attr 2]
+ } else {
+ set attr_form [_guess_form $attr_value attr_value]
+ }
+ set attr_form [_map_name $attr_form _FORM]
- _handle_attribute $attr_name $attr_value $attr_form
+ _handle_attribute $attr_name $attr_value $attr_form
+ }
}
_defer_output $_abbrev_section {