[ELF] Fix incorrect sorting of .init_array / .fini_array sections.
The main problem is in the predicate passed to the `std::stable_sort()`. This predicate always returns false if **both** section's names do not start with `.init_array` or `.fini_array` prefixes. In short, it does not define a strict weak orderng. Suppose we have the following sections: .A .init_array.1 .init_array.2 The predicate states that: not .init_array.1 < .A not .A < .init_array.2 but .init_array.1 < .init_array.2 !!! The second problem is that `.init_array` section without number should go last in the list. Not it has the lowest priority '0' and goes first. The patch fixes both of the problems. llvm-svn: 209875
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@ -10,32 +10,46 @@
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#include "ArrayOrderPass.h"
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#include <algorithm>
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#include <limits>
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namespace lld {
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namespace elf {
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void ArrayOrderPass::perform(std::unique_ptr<MutableFile> &f) {
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auto definedAtoms = f->definedAtoms();
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std::stable_sort(definedAtoms.begin(), definedAtoms.end(),
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[](const DefinedAtom *left, const DefinedAtom *right) {
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if (left->sectionChoice() != DefinedAtom::sectionCustomRequired ||
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right->sectionChoice() != DefinedAtom::sectionCustomRequired)
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// Move sections need to be sorted into the separate continious group.
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// That reduces a number of sorting elements and simplifies conditions
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// in the sorting predicate.
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auto last = std::stable_partition(definedAtoms.begin(), definedAtoms.end(),
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[](const DefinedAtom *atom) {
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if (atom->sectionChoice() != DefinedAtom::sectionCustomRequired)
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return false;
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StringRef name = atom->customSectionName();
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return name.startswith(".init_array") || name.startswith(".fini_array");
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});
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std::stable_sort(definedAtoms.begin(), last,
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[](const DefinedAtom *left, const DefinedAtom *right) {
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StringRef leftSec = left->customSectionName();
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StringRef rightSec = right->customSectionName();
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// Both sections start with the same array type.
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if (!(leftSec.startswith(".init_array") &&
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rightSec.startswith(".init_array")) &&
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!(leftSec.startswith(".fini_array") &&
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rightSec.startswith(".fini_array")))
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return false;
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// Drop the front dot from the section name and get
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// an optional section's number starting after the second dot.
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StringRef leftNum = leftSec.drop_front().rsplit('.').second;
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StringRef rightNum = rightSec.drop_front().rsplit('.').second;
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// Get priortiy
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uint16_t leftPriority = 0;
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leftSec.rsplit('.').second.getAsInteger(10, leftPriority);
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uint16_t rightPriority = 0;
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rightSec.rsplit('.').second.getAsInteger(10, rightPriority);
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// Sort {.init_array, .fini_array}[.<num>] sections
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// according to their number. Sections without optional
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// numer suffix should go last.
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uint32_t leftPriority = std::numeric_limits<uint32_t>::max();
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if (!leftNum.empty())
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leftNum.getAsInteger(10, leftPriority);
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uint32_t rightPriority = std::numeric_limits<uint32_t>::max();
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if (!rightNum.empty())
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rightNum.getAsInteger(10, rightPriority);
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return leftPriority < rightPriority;
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});
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@ -10,11 +10,31 @@ FileHeader:
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Machine: EM_X86_64
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Content: "1100000000000000"
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AddressAlign: 8
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Flags: [SHF_ALLOC, SHF_EXECINSTR]
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- Name: .init_array.2
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Type: SHT_INIT_ARRAY
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Content: "0200000000000000"
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AddressAlign: 8
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Flags: [SHF_ALLOC]
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- Name: .init_array.3
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Type: SHT_INIT_ARRAY
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Content: "0300000000000000"
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AddressAlign: 8
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Flags: [SHF_ALLOC]
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- Name: .init_array
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Type: SHT_INIT_ARRAY
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Content: "9900000000000000"
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AddressAlign: 8
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Flags: [SHF_ALLOC]
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- Name: .data
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Type: SHT_PROGBITS
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Content: "2200000000000000"
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AddressAlign: 8
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Flags: [SHF_ALLOC, SHF_WRITE]
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- Name: .init_array.1
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Type: SHT_INIT_ARRAY
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Content: "0100000000000000"
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@ -23,15 +43,31 @@ Sections:
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Symbols:
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Local:
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- Name: .text
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Type: STT_SECTION
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Section: .text
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- Name: .data
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Type: STT_SECTION
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Section: .data
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- Name: .init_array.3
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Type: STT_SECTION
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Section: .init_array.3
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- Name: .init_array.2
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Type: STT_SECTION
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Section: .init_array.2
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- Name: .init_array.1
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Type: STT_SECTION
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Section: .init_array.1
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- Name: .init_array
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Type: STT_SECTION
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Section: .init_array
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#CHECK: defined-atoms:
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#CHECK: content: [ 01,
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#CHECK: section-name: .init_array.1
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#CHECK: content: [ 02,
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#CHECK: section-name: .init_array.2
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#CHECK: content: [ 03,
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#CHECK: section-name: .init_array.3
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#CHECK: content: [ 99,
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#CHECK: section-name: .init_array
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