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PR25058 - Better support fn DIEs referring to symbols using DW_AT_ranges

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In the previous commit 2f7248f, we were just taking the first address
referred to by the DW_AT_ranges attribute as being the address of the
symbol of the function we are looking at.  But there can be cases
where this is not true, as explained at
https://sourceware.org/bugzilla/show_bug.cgi?id=25058#c7.

We really need to get the first address that represents an exported
and defined function symbol, which is pointed to by the DW_AT_ranges
attribute.

And this is what this patch does.

	* src/abg-dwarf-reader.cc
	(read_context::get_first_exported_fn_address_from_DW_AT_ranges):
	Rename read_context::get_first_address_from_DW_AT_ranges into
	this.  Walk through the addresses referred to by the DW_AT_ranges
	attribute until we find one that is for an exported function
	symbol, rather than just picking the first address of the set.
	(read_context::get_function_address): Adjust.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Dodji Seketeli 2019-10-04 10:05:42 +02:00
parent 2f7248f340
commit 5b9f5efab2
1 changed files with 25 additions and 11 deletions
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36
src/abg-dwarf-reader.cc
View File

@ -8565,8 +8565,8 @@ public:
return addr;
}
/// Get the first address in the set of addresses referred to by the
/// DW_AT_ranges attribute of a given DIE.
/// Get the first exported function address in the set of addresses
/// referred to by the DW_AT_ranges attribute of a given DIE.
///
/// @param die the DIE we are considering.
///
@ -8576,14 +8576,29 @@ public:
/// true. Otherwise, no value is set into this output parameter.
///
/// @return true iff the DIE @p die does have a DW_AT_ranges
/// attribute and an address was found in its sequence value.
/// attribute and an address of an exported function was found in
/// its sequence value.
bool
get_first_address_from_DW_AT_ranges(Dwarf_Die* die, Dwarf_Addr& address) const
get_first_exported_fn_address_from_DW_AT_ranges(Dwarf_Die* die,
Dwarf_Addr& address) const
{
Dwarf_Addr base;
Dwarf_Addr end_addr;
if (dwarf_ranges(die, /*offset=*/0, &base, &address, &end_addr))
return true;
ptrdiff_t offset = 0;
do
{
Dwarf_Addr addr, fn_addr;
if ((offset = dwarf_ranges(die, offset, &base, &addr, &end_addr)) >= 0)
{
fn_addr = maybe_adjust_fn_sym_address(addr);
if (function_symbol_is_exported(fn_addr))
{
address = fn_addr;
return true;
}
}
} while (offset > 0);
return false;
}
@ -8603,18 +8618,17 @@ public:
bool
get_function_address(Dwarf_Die* function_die, Dwarf_Addr& address) const
{
Dwarf_Addr fn_address = 0;
if (!die_address_attribute(function_die, DW_AT_low_pc, fn_address))
if (!die_address_attribute(function_die, DW_AT_low_pc, address))
// So no DW_AT_low_pc was found. Let's see if the function DIE
// has got a DW_AT_ranges attribute instead. If it does, the
// first address of the set of addresses represented by the
// value of that DW_AT_ranges represents the function (symbol)
// address we are looking for.
if (!get_first_address_from_DW_AT_ranges(function_die, fn_address))
if (!get_first_exported_fn_address_from_DW_AT_ranges(function_die,
address))
return false;
fn_address = maybe_adjust_fn_sym_address(fn_address);
address = fn_address;
address = maybe_adjust_fn_sym_address(address);
return true;
}