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[GOLD] correct grouping of stubs 

This patch rewrites the rather obscure can_add_to_stub_group, fixing
a problem with the handling of sections containing conditional
external branches.  When a section group contains any such section,
the group size needs to be limited to a much smaller size than groups
with only non-conditional external branches.

	PR 20523
	* powerpc.cc (class Stub_control): Add has14_.  Comment owner_.
	(Stub_control::can_add_to_stub_group): Correct grouping of
	sections containing 14-bit external branches.  When returning
	false, set state_ to reflect the fact that we have one section
	for the next group.  Rewrite most of function for clarity.
	Add and expand comments.
	(Target_powerpc::do_relax): Print stub group size retry in hex.
This commit is contained in:
Alan Modra 2016-08-30 11:58:05 +09:30
parent 7229b687db
commit 57f6d32dea
2 changed files with 82 additions and 34 deletions
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11
gold/ChangeLog
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@ -1,3 +1,14 @@
2016-08-30 Alan Modra <amodra@gmail.com>
PR 20523
* powerpc.cc (class Stub_control): Add has14_. Comment owner_.
(Stub_control::can_add_to_stub_group): Correct grouping of
sections containing 14-bit external branches. When returning
false, set state_ to reflect the fact that we have one section
for the next group. Rewrite most of function for clarity.
Add and expand comments.
(Target_powerpc::do_relax): Print stub group size retry in hex.
2016-08-26 Han Shen <shenhan@google.com>
PR gold/20529 - relaxing loop never ends.

105
gold/powerpc.cc
View File

@ -2441,7 +2441,7 @@ class Stub_control
: state_(NO_GROUP), stub_group_size_(abs(size)),
stub14_group_size_(abs(size) >> 10),
stubs_always_before_branch_(size < 0),
suppress_size_errors_(no_size_errors),
suppress_size_errors_(no_size_errors), has14_(false),
group_end_addr_(0), owner_(NULL), output_section_(NULL)
{
}
@ -2482,21 +2482,23 @@ class Stub_control
uint32_t stub14_group_size_;
bool stubs_always_before_branch_;
bool suppress_size_errors_;
bool has14_;
uint64_t group_end_addr_;
// owner_ and output_section_ specify the section to which stubs are
// attached. The stubs are placed at the end of this section.
const Output_section::Input_section* owner_;
Output_section* output_section_;
};
// Return true iff input section can be handled by current stub
// group.
// group. Sections are presented to this function in reverse order,
// so the first section is the tail of the group.
bool
Stub_control::can_add_to_stub_group(Output_section* o,
const Output_section::Input_section* i,
bool has14)
{
uint32_t group_size
= has14 ? this->stub14_group_size_ : this->stub_group_size_;
bool whole_sec = o->order() == ORDER_INIT || o->order() == ORDER_FINI;
uint64_t this_size;
uint64_t start_addr = o->address();
@ -2510,46 +2512,81 @@ Stub_control::can_add_to_stub_group(Output_section* o,
start_addr += i->relobj()->output_section_offset(i->shndx());
this_size = i->data_size();
}
uint64_t end_addr = start_addr + this_size;
bool toobig = this_size > group_size;
if (toobig && !this->suppress_size_errors_)
uint32_t group_size
= has14 ? this->stub14_group_size_ : this->stub_group_size_;
uint64_t end_addr = start_addr + this_size;
if (this_size > group_size && !this->suppress_size_errors_)
gold_warning(_("%s:%s exceeds group size"),
i->relobj()->name().c_str(),
i->relobj()->section_name(i->shndx()).c_str());
if (this->state_ != HAS_STUB_SECTION
&& (!whole_sec || this->output_section_ != o)
&& (this->state_ == NO_GROUP
|| this->group_end_addr_ - end_addr < group_size))
{
this->owner_ = i;
this->output_section_ = o;
}
this->has14_ = this->has14_ || has14;
group_size = this->has14_ ? this->stub14_group_size_ : this->stub_group_size_;
if (this->state_ == NO_GROUP)
if (this->state_ == HAS_STUB_SECTION)
{
this->state_ = FINDING_STUB_SECTION;
this->group_end_addr_ = end_addr;
}
else if (this->group_end_addr_ - start_addr < group_size)
;
// Adding this section would make the group larger than GROUP_SIZE.
else if (this->state_ == FINDING_STUB_SECTION
&& !this->stubs_always_before_branch_
&& !toobig)
{
// But wait, there's more! Input sections up to GROUP_SIZE
// bytes before the stub table can be handled by it too.
this->state_ = HAS_STUB_SECTION;
this->group_end_addr_ = end_addr;
// Can we add this section, which is before the stubs, to the
// group?
if (this->group_end_addr_ - start_addr <= group_size)
return true;
}
else
{
this->state_ = NO_GROUP;
return false;
// Stubs are added at the end of "owner_".
// The current section can always be the stub owner, except when
// whole_sec is true and the current section isn't the last of
// the pasted sections. (This restriction for the whole_sec
// case is just to simplify the corner case mentioned in
// group_sections.)
// Note that "owner_" itself is not necessarily part of the
// group of sections served by these stubs!
if (!whole_sec || this->output_section_ != o)
{
this->owner_ = i;
this->output_section_ = o;
}
if (this->state_ == FINDING_STUB_SECTION)
{
if (this->group_end_addr_ - start_addr <= group_size)
return true;
// The group after the stubs has reached maximum size.
// Now see about adding sections before the stubs to the
// group. If the current section has a 14-bit branch and
// the group after the stubs exceeds stub14_group_size_
// (because they didn't have 14-bit branches), don't add
// sections before the stubs: The size of stubs for such a
// large group may exceed the reach of a 14-bit branch.
if (!this->stubs_always_before_branch_
&& this_size <= group_size
&& this->group_end_addr_ - end_addr <= group_size)
{
this->state_ = HAS_STUB_SECTION;
this->group_end_addr_ = end_addr;
return true;
}
}
else if (this->state_ == NO_GROUP)
{
// Only here on very first use of Stub_control
this->state_ = FINDING_STUB_SECTION;
this->group_end_addr_ = end_addr;
return true;
}
else
gold_unreachable();
}
return true;
// The section fails to fit in the current group. Set up a few
// things for the next group. owner_ and output_section_ will be
// set later after we've retrieved those values for the current
// group.
this->state_ = FINDING_STUB_SECTION;
this->has14_ = has14;
this->group_end_addr_ = end_addr;
return false;
}
// Look over all the input sections, deciding where to place stubs.
@ -2887,7 +2924,7 @@ Target_powerpc<size, big_endian>::do_relax(int pass,
}
this->stub_tables_.clear();
this->stub_group_size_ = this->stub_group_size_ / 4 * 3;
gold_info(_("%s: stub group size is too large; retrying with %d"),
gold_info(_("%s: stub group size is too large; retrying with %#x"),
program_name, this->stub_group_size_);
this->group_sections(layout, task, true);
}