[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.
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@ -1,3 +1,14 @@
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2016-08-30 Alan Modra <amodra@gmail.com>
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PR 20523
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* powerpc.cc (class Stub_control): Add has14_. Comment owner_.
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(Stub_control::can_add_to_stub_group): Correct grouping of
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sections containing 14-bit external branches. When returning
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false, set state_ to reflect the fact that we have one section
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for the next group. Rewrite most of function for clarity.
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Add and expand comments.
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(Target_powerpc::do_relax): Print stub group size retry in hex.
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2016-08-26 Han Shen <shenhan@google.com>
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PR gold/20529 - relaxing loop never ends.
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@ -2441,7 +2441,7 @@ class Stub_control
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: state_(NO_GROUP), stub_group_size_(abs(size)),
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stub14_group_size_(abs(size) >> 10),
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stubs_always_before_branch_(size < 0),
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suppress_size_errors_(no_size_errors),
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suppress_size_errors_(no_size_errors), has14_(false),
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group_end_addr_(0), owner_(NULL), output_section_(NULL)
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{
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}
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@ -2482,21 +2482,23 @@ class Stub_control
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uint32_t stub14_group_size_;
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bool stubs_always_before_branch_;
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bool suppress_size_errors_;
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bool has14_;
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uint64_t group_end_addr_;
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// owner_ and output_section_ specify the section to which stubs are
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// attached. The stubs are placed at the end of this section.
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const Output_section::Input_section* owner_;
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Output_section* output_section_;
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};
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// Return true iff input section can be handled by current stub
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// group.
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// group. Sections are presented to this function in reverse order,
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// so the first section is the tail of the group.
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bool
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Stub_control::can_add_to_stub_group(Output_section* o,
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const Output_section::Input_section* i,
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bool has14)
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{
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uint32_t group_size
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= has14 ? this->stub14_group_size_ : this->stub_group_size_;
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bool whole_sec = o->order() == ORDER_INIT || o->order() == ORDER_FINI;
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uint64_t this_size;
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uint64_t start_addr = o->address();
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@ -2510,46 +2512,81 @@ Stub_control::can_add_to_stub_group(Output_section* o,
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start_addr += i->relobj()->output_section_offset(i->shndx());
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this_size = i->data_size();
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}
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uint64_t end_addr = start_addr + this_size;
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bool toobig = this_size > group_size;
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if (toobig && !this->suppress_size_errors_)
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uint32_t group_size
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= has14 ? this->stub14_group_size_ : this->stub_group_size_;
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uint64_t end_addr = start_addr + this_size;
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if (this_size > group_size && !this->suppress_size_errors_)
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gold_warning(_("%s:%s exceeds group size"),
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i->relobj()->name().c_str(),
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i->relobj()->section_name(i->shndx()).c_str());
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if (this->state_ != HAS_STUB_SECTION
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&& (!whole_sec || this->output_section_ != o)
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&& (this->state_ == NO_GROUP
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|| this->group_end_addr_ - end_addr < group_size))
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this->has14_ = this->has14_ || has14;
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group_size = this->has14_ ? this->stub14_group_size_ : this->stub_group_size_;
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if (this->state_ == HAS_STUB_SECTION)
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{
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// Can we add this section, which is before the stubs, to the
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// group?
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if (this->group_end_addr_ - start_addr <= group_size)
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return true;
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}
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else
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{
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// Stubs are added at the end of "owner_".
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// The current section can always be the stub owner, except when
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// whole_sec is true and the current section isn't the last of
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// the pasted sections. (This restriction for the whole_sec
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// case is just to simplify the corner case mentioned in
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// group_sections.)
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// Note that "owner_" itself is not necessarily part of the
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// group of sections served by these stubs!
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if (!whole_sec || this->output_section_ != o)
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{
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this->owner_ = i;
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this->output_section_ = o;
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}
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if (this->state_ == NO_GROUP)
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if (this->state_ == FINDING_STUB_SECTION)
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{
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this->state_ = FINDING_STUB_SECTION;
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this->group_end_addr_ = end_addr;
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}
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else if (this->group_end_addr_ - start_addr < group_size)
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;
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// Adding this section would make the group larger than GROUP_SIZE.
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else if (this->state_ == FINDING_STUB_SECTION
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&& !this->stubs_always_before_branch_
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&& !toobig)
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if (this->group_end_addr_ - start_addr <= group_size)
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return true;
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// The group after the stubs has reached maximum size.
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// Now see about adding sections before the stubs to the
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// group. If the current section has a 14-bit branch and
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// the group after the stubs exceeds stub14_group_size_
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// (because they didn't have 14-bit branches), don't add
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// sections before the stubs: The size of stubs for such a
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// large group may exceed the reach of a 14-bit branch.
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if (!this->stubs_always_before_branch_
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&& this_size <= group_size
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&& this->group_end_addr_ - end_addr <= group_size)
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{
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// But wait, there's more! Input sections up to GROUP_SIZE
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// bytes before the stub table can be handled by it too.
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this->state_ = HAS_STUB_SECTION;
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this->group_end_addr_ = end_addr;
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return true;
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}
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}
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else if (this->state_ == NO_GROUP)
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{
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// Only here on very first use of Stub_control
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this->state_ = FINDING_STUB_SECTION;
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this->group_end_addr_ = end_addr;
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return true;
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}
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else
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{
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this->state_ = NO_GROUP;
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return false;
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gold_unreachable();
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}
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return true;
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// The section fails to fit in the current group. Set up a few
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// things for the next group. owner_ and output_section_ will be
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// set later after we've retrieved those values for the current
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// group.
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this->state_ = FINDING_STUB_SECTION;
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this->has14_ = has14;
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this->group_end_addr_ = end_addr;
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return false;
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}
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// Look over all the input sections, deciding where to place stubs.
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@ -2887,7 +2924,7 @@ Target_powerpc<size, big_endian>::do_relax(int pass,
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}
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this->stub_tables_.clear();
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this->stub_group_size_ = this->stub_group_size_ / 4 * 3;
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gold_info(_("%s: stub group size is too large; retrying with %d"),
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gold_info(_("%s: stub group size is too large; retrying with %#x"),
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program_name, this->stub_group_size_);
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this->group_sections(layout, task, true);
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}
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