Group text sections with prefixes .text.unlikely,.text.hot and .text.startup
by default. 2012-12-18 Sriraman Tallam <tmsriram@google.com> * layout.cc (Layout::is_section_name_prefix_grouped): New function. * layout.h (Layout::is_section_name_prefix_grouped): New function. * output.cc (Output_section::add_input_section): Check if section name contains special prefix. Keep input sections to sort such sections. (Output_section::Input_section_sort_section_order_index_compare ::operator()): Group sections according to prefixes. * (Output_section::sort_attached_input_sections): Add condition to Input_section_entry constructor call. * testsuite/Makefile.am (text_section_grouping): New test. * testsuite/Makefile.in: Regenerate. * testsuite/text_section_grouping.cc: New file. * testsuite/text_section_grouping.sh: New file.
This commit is contained in:
Sriraman Tallam
parent
e0e51b2391
commit
28f2a4ac6f
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@ -1,3 +1,19 @@
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2012-12-18 Sriraman Tallam <tmsriram@google.com>
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* layout.cc (Layout::is_section_name_prefix_grouped): New function.
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* layout.h (Layout::is_section_name_prefix_grouped): New function.
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* output.cc (Output_section::add_input_section): Check if section
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name contains special prefix. Keep input sections to sort such
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sections.
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(Output_section::Input_section_sort_section_order_index_compare
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::operator()): Group sections according to prefixes.
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* (Output_section::sort_attached_input_sections): Add condition
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to Input_section_entry constructor call.
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* testsuite/Makefile.am (text_section_grouping): New test.
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* testsuite/Makefile.in: Regenerate.
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* testsuite/text_section_grouping.cc: New file.
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* testsuite/text_section_grouping.sh: New file.
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2012-12-17 Nick Clifton <nickc@redhat.com>
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* Makefile.am: Add copyright notice.
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@ -2409,6 +2409,20 @@ Layout::relaxation_loop_body(
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return off;
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}
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// By default, gold groups input sections with certain prefixes. This
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// function returns true if this section name NAME contains such a prefix.
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bool
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Layout::is_section_name_prefix_grouped(const char *name)
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{
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if (is_prefix_of(".text.unlikely", name)
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|| is_prefix_of(".text.startup", name)
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|| is_prefix_of(".text.hot", name))
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return true;
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return false;
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}
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// Search the list of patterns and find the postion of the given section
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// name in the output section. If the section name matches a glob
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// pattern and a non-glob name, then the non-glob position takes
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@ -552,6 +552,11 @@ class Layout
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// Maps section SECN to SEGMENT s.
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void
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insert_section_segment_map(Const_section_id secn, Unique_segment_info *s);
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// By default, gold groups input sections with certain prefixes. This
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// function returns true if this section name NAME contains such a prefix.
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bool
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is_section_name_prefix_grouped(const char *name);
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bool
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is_section_ordering_specified()
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@ -2478,6 +2478,19 @@ Output_section::add_input_section(Layout* layout,
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}
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}
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// The GNU linker groups input sections whose names match .text.unlikely.*.
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// This is used to get better code layout. We are compatible.
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// Additionally, it could also be beneficial to group .text.hot.*,
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// .text.startup.* prefixed input sections. Function
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// "is_section_name_prefix_grouped" in layout.cc determines the input
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// section prefixes that must be grouped.
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if (!have_sections_script
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&& !parameters->options().relocatable()
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&& !this->input_section_order_specified()
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&& !this->must_sort_attached_input_sections()
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&& layout->is_section_name_prefix_grouped(secname))
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this->set_input_section_order_specified();
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// We need to keep track of this section if we are already keeping
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// track of sections, or if we are relaxing. Also, if this is a
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// section which requires sorting, or which may require sorting in
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@ -2491,7 +2504,8 @@ Output_section::add_input_section(Layout* layout,
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|| this->must_sort_attached_input_sections()
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|| parameters->options().user_set_Map()
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|| parameters->target().may_relax()
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|| layout->is_section_ordering_specified())
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|| layout->is_section_ordering_specified()
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|| this->input_section_order_specified())
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{
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Input_section isecn(object, shndx, input_section_size, addralign);
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/* If section ordering is requested by specifying a ordering file,
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@ -3484,7 +3498,9 @@ Output_section::Input_section_sort_init_fini_compare::operator()(
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// Return true if S1 should come before S2. Sections that do not match
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// any pattern in the section ordering file are placed ahead of the sections
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// that match some pattern.
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// that match some pattern. This function is also used to group text according
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// to their prefix. The following prefixes are recognized: ".text.startup",
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// ".text.hot", and ".text.unlikely".
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bool
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Output_section::Input_section_sort_section_order_index_compare::operator()(
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@ -3494,11 +3510,59 @@ Output_section::Input_section_sort_section_order_index_compare::operator()(
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unsigned int s1_secn_index = s1.input_section().section_order_index();
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unsigned int s2_secn_index = s2.input_section().section_order_index();
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// Keep input order if section ordering cannot determine order.
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if (s1_secn_index == s2_secn_index)
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return s1.index() < s2.index();
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// If section ordering is specified, it takes precedence.
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if (s1_secn_index != s2_secn_index)
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return s1_secn_index < s2_secn_index;
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return s1_secn_index < s2_secn_index;
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// Sort all the sections with no names to the end.
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if (!s1.section_has_name() || !s2.section_has_name())
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{
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if (s1.section_has_name())
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return true;
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if (s2.section_has_name())
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return false;
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return s1.index() < s2.index();
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}
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// If it is a text section use the following order:
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// .text.unlikely, .text.startup, .text.hot. The prefixes
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// must match those in function is_section_name_prefix_grouped
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// in layout.cc
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const char* section_prefix [] =
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{
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".text.unlikely",
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".text.startup",
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".text.hot"
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};
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const unsigned int num_prefixes
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= sizeof(section_prefix) / sizeof(const char*);
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unsigned int s1_group_index = num_prefixes;
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unsigned int s2_group_index = num_prefixes;
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unsigned int flag_done = 0;
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for (unsigned int i = 0; i < num_prefixes && flag_done < 2; i++)
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{
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if (s1_group_index == num_prefixes
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&& is_prefix_of(section_prefix[i], s1.section_name().c_str()))
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{
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s1_group_index = i;
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flag_done++;
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}
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if (s2_group_index == num_prefixes
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&& is_prefix_of(section_prefix[i], s2.section_name().c_str()))
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{
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s2_group_index = i;
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flag_done++;
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}
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}
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if (s1_group_index == s2_group_index)
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return s1.index() < s2.index();
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else
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return s1_group_index < s2_group_index;
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}
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// This updates the section order index of input sections according to the
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@ -3559,7 +3623,8 @@ Output_section::sort_attached_input_sections()
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p != this->input_sections_.end();
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++p, ++i)
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sort_list.push_back(Input_section_sort_entry(*p, i,
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this->must_sort_attached_input_sections()));
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(this->must_sort_attached_input_sections()
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|| this->input_section_order_specified())));
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// Sort the input sections.
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if (this->must_sort_attached_input_sections())
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@ -250,6 +250,16 @@ final_layout: final_layout.o final_layout_sequence.txt gcctestdir/ld
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final_layout.stdout: final_layout
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$(TEST_NM) -n --synthetic final_layout > final_layout.stdout
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check_SCRIPTS += text_section_grouping.sh
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check_DATA += text_section_grouping.stdout
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MOSTLYCLEANFILES += text_section_grouping
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text_section_grouping.o: text_section_grouping.cc
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$(CXXCOMPILE) -O0 -c -ffunction-sections -g -o $@ $<
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text_section_grouping: text_section_grouping.o gcctestdir/ld
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$(CXXLINK) -Bgcctestdir/ text_section_grouping.o
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text_section_grouping.stdout: text_section_grouping
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$(TEST_NM) -n --synthetic text_section_grouping > text_section_grouping.stdout
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check_PROGRAMS += icf_virtual_function_folding_test
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MOSTLYCLEANFILES += icf_virtual_function_folding_test
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icf_virtual_function_folding_test.o: icf_virtual_function_folding_test.cc
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@ -81,6 +81,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_safe_test.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_safe_so_test.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ final_layout.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ text_section_grouping.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_preemptible_functions_test.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_string_merge_test.sh \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_sht_rel_addend_test.sh \
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@ -111,6 +112,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_safe_so_test_1.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_safe_so_test_2.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ final_layout.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ text_section_grouping.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_preemptible_functions_test.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_string_merge_test.stdout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_sht_rel_addend_test.stdout \
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@ -122,6 +124,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_test icf_keep_unique_test \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_safe_test icf_safe_so_test \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ final_layout \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ text_section_grouping \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ final_layout_sequence.txt \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_virtual_function_folding_test \
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ icf_preemptible_functions_test \
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@ -3701,6 +3704,8 @@ icf_safe_so_test.sh.log: icf_safe_so_test.sh
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@p='icf_safe_so_test.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
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final_layout.sh.log: final_layout.sh
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@p='final_layout.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
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text_section_grouping.sh.log: text_section_grouping.sh
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@p='text_section_grouping.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
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icf_preemptible_functions_test.sh.log: icf_preemptible_functions_test.sh
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@p='icf_preemptible_functions_test.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
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icf_string_merge_test.sh.log: icf_string_merge_test.sh
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@ -4348,6 +4353,12 @@ uninstall-am:
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK) -Bgcctestdir/ -Wl,--section-ordering-file,final_layout_sequence.txt final_layout.o
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@GCC_TRUE@@NATIVE_LINKER_TRUE@final_layout.stdout: final_layout
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_NM) -n --synthetic final_layout > final_layout.stdout
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@GCC_TRUE@@NATIVE_LINKER_TRUE@text_section_grouping.o: text_section_grouping.cc
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXCOMPILE) -O0 -c -ffunction-sections -g -o $@ $<
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@GCC_TRUE@@NATIVE_LINKER_TRUE@text_section_grouping: text_section_grouping.o gcctestdir/ld
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK) -Bgcctestdir/ text_section_grouping.o
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@GCC_TRUE@@NATIVE_LINKER_TRUE@text_section_grouping.stdout: text_section_grouping
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_NM) -n --synthetic text_section_grouping > text_section_grouping.stdout
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@GCC_TRUE@@NATIVE_LINKER_TRUE@icf_virtual_function_folding_test.o: icf_virtual_function_folding_test.cc
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@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXCOMPILE) -O0 -c -ffunction-sections -fPIE -g -o $@ $<
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@GCC_TRUE@@NATIVE_LINKER_TRUE@icf_virtual_function_folding_test: icf_virtual_function_folding_test.o gcctestdir/ld
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@ -0,0 +1,72 @@
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// text_section_grouping.cc -- a test case for gold
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// Copyright 2012 Free Software Foundation, Inc.
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// Written by Sriraman Tallam <tmsriram@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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// The goal of this program is to verify if .text sections are grouped
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// according to prefix. .text.unlikely, .text.startup and .text.hot should
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// be grouped and placed together.
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extern "C"
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__attribute__ ((section(".text.hot.foo")))
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int hot_foo()
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{
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return 1;
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}
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extern "C"
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__attribute__ ((section(".text.startup.foo")))
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int startup_foo()
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{
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return 1;
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}
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extern "C"
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__attribute__ ((section(".text.unlikely.foo")))
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int unlikely_foo()
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{
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return 1;
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}
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extern "C"
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__attribute__ ((section(".text.hot.bar")))
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int hot_bar()
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{
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return 1;
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}
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extern "C"
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__attribute__ ((section(".text.startup.bar")))
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int startup_bar()
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{
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return 1;
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}
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extern "C"
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__attribute__ ((section(".text.unlikely.bar")))
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int unlikely_bar()
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{
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return 1;
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}
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int main()
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{
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return 1;
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}
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@ -0,0 +1,65 @@
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#!/bin/sh
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# text_section_grouping.sh -- test
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# Copyright 2012 Free Software Foundation, Inc.
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# Written by Sriraman Tallam <tmsriram@google.com>.
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# This file is part of gold.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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||||
|
||||
# You should have received a copy of the GNU General Public License
|
||||
# along with this program; if not, write to the Free Software
|
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# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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# MA 02110-1301, USA.
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# The goal of this program is to verify if .text sections are grouped
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# according to prefix. .text.unlikely, .text.startup and .text.hot should
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# be grouped and placed together.
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set -e
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check()
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{
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awk "
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BEGIN { saw1 = 0; saw2 = 0; err = 0; }
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/.*$2\$/ { saw1 = 1; }
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/.*$3\$/ {
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saw2 = 1;
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if (!saw1)
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{
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printf \"layout of $2 and $3 is not right\\n\";
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err = 1;
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exit 1;
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}
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}
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END {
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if (!saw1 && !err)
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{
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printf \"did not see $2\\n\";
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exit 1;
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}
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if (!saw2 && !err)
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{
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printf \"did not see $3\\n\";
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exit 1;
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}
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}" $1
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}
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# addr (unlikely_*) < addr (startup_*) < addr (hot_*)
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check text_section_grouping.stdout "unlikely_foo" "startup_foo"
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check text_section_grouping.stdout "startup_foo" "hot_foo"
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check text_section_grouping.stdout "unlikely_bar" "startup_bar"
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check text_section_grouping.stdout "startup_bar" "hot_bar"
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check text_section_grouping.stdout "unlikely_foo" "startup_bar"
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check text_section_grouping.stdout "startup_foo" "hot_bar"
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