Implement --long-plt flag (ARM only).
gold/
PR gold/18780
* arm.cc (Target_arm::do_make_data_plt): Choose PLT generator based
on value of --long-plt flag.
(Output_data_plt_arm_standard::do_get_plt_entry_size): Moved to
Output_data_plt_arm_short.
(Output_data_plt_arm_standard::do_fill_plt_entry): Likewise.
(Output_data_plt_arm_standard::plt_entry): Likewise.
(Output_data_plt_arm_standard::do_fill_first_plt_entry): Fix
variable reference.
(Output_data_plt_arm_short): New class.
(Output_data_plt_arm_short::do_fill_plt_entry): Error out on too large
PLT offsets instead of asserting.
(Output_data_plt_arm_long): New class.
* options.h (General_options): Define --long-plt flag.
This commit is contained in:
Peter Collingbourne
Cary Coutant
parent
33e0d1ca50
commit
ce3e49806d
3 changed files with 130 additions and 24 deletions
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@ -1,3 +1,20 @@
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2015-12-17 Peter Collingbourne <pcc@google.com>
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PR gold/18780
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* arm.cc (Target_arm::do_make_data_plt): Choose PLT generator based
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on value of --long-plt flag.
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(Output_data_plt_arm_standard::do_get_plt_entry_size): Moved to
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Output_data_plt_arm_short.
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(Output_data_plt_arm_standard::do_fill_plt_entry): Likewise.
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(Output_data_plt_arm_standard::plt_entry): Likewise.
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(Output_data_plt_arm_standard::do_fill_first_plt_entry): Fix
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variable reference.
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(Output_data_plt_arm_short): New class.
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(Output_data_plt_arm_short::do_fill_plt_entry): Error out on too large
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PLT offsets instead of asserting.
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(Output_data_plt_arm_long): New class.
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* options.h (General_options): Define --long-plt flag.
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2015-12-16 Roland McGrath <mcgrathr@google.com>
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PR ld/17473
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133
gold/arm.cc
133
gold/arm.cc
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@ -62,7 +62,10 @@ template<bool big_endian>
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class Output_data_plt_arm;
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template<bool big_endian>
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class Output_data_plt_arm_standard;
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class Output_data_plt_arm_short;
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template<bool big_endian>
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class Output_data_plt_arm_long;
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template<bool big_endian>
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class Stub_table;
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@ -2554,7 +2557,11 @@ class Target_arm : public Sized_target<32, big_endian>
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Output_data_space* got_irelative)
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{
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gold_assert(got_plt != NULL && got_irelative != NULL);
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return new Output_data_plt_arm_standard<big_endian>(
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if (parameters->options().long_plt())
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return new Output_data_plt_arm_long<big_endian>(
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layout, got, got_plt, got_irelative);
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else
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return new Output_data_plt_arm_short<big_endian>(
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layout, got, got_plt, got_irelative);
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}
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@ -7715,29 +7722,14 @@ class Output_data_plt_arm_standard : public Output_data_plt_arm<big_endian>
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do_first_plt_entry_offset() const
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{ return sizeof(first_plt_entry); }
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// Return the size of a PLT entry.
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virtual unsigned int
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do_get_plt_entry_size() const
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{ return sizeof(plt_entry); }
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virtual void
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do_fill_first_plt_entry(unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address);
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virtual void
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do_fill_plt_entry(unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address,
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unsigned int got_offset,
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unsigned int plt_offset);
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private:
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// Template for the first PLT entry.
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static const uint32_t first_plt_entry[5];
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// Template for subsequent PLT entries.
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static const uint32_t plt_entry[3];
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};
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// ARM PLTs.
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@ -7765,7 +7757,7 @@ Output_data_plt_arm_standard<big_endian>::do_fill_first_plt_entry(
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{
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// Write first PLT entry. All but the last word are constants.
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const size_t num_first_plt_words = (sizeof(first_plt_entry)
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/ sizeof(plt_entry[0]));
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/ sizeof(first_plt_entry[0]));
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for (size_t i = 0; i < num_first_plt_words - 1; i++)
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elfcpp::Swap<32, big_endian>::writeval(pov + i * 4, first_plt_entry[i]);
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// Last word in first PLT entry is &GOT[0] - .
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@ -7774,9 +7766,39 @@ Output_data_plt_arm_standard<big_endian>::do_fill_first_plt_entry(
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}
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// Subsequent entries in the PLT.
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// This class generates short (12-byte) entries, for displacements up to 2^28.
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template<bool big_endian>
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const uint32_t Output_data_plt_arm_standard<big_endian>::plt_entry[3] =
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class Output_data_plt_arm_short : public Output_data_plt_arm_standard<big_endian>
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{
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public:
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Output_data_plt_arm_short(Layout* layout,
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Arm_output_data_got<big_endian>* got,
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Output_data_space* got_plt,
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Output_data_space* got_irelative)
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: Output_data_plt_arm_standard<big_endian>(layout, got, got_plt, got_irelative)
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{ }
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protected:
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// Return the size of a PLT entry.
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virtual unsigned int
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do_get_plt_entry_size() const
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{ return sizeof(plt_entry); }
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virtual void
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do_fill_plt_entry(unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address,
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unsigned int got_offset,
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unsigned int plt_offset);
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private:
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// Template for subsequent PLT entries.
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static const uint32_t plt_entry[3];
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};
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template<bool big_endian>
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const uint32_t Output_data_plt_arm_short<big_endian>::plt_entry[3] =
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{
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0xe28fc600, // add ip, pc, #0xNN00000
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0xe28cca00, // add ip, ip, #0xNN000
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@ -7785,7 +7807,69 @@ const uint32_t Output_data_plt_arm_standard<big_endian>::plt_entry[3] =
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template<bool big_endian>
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void
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Output_data_plt_arm_standard<big_endian>::do_fill_plt_entry(
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Output_data_plt_arm_short<big_endian>::do_fill_plt_entry(
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unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address,
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unsigned int got_offset,
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unsigned int plt_offset)
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{
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int32_t offset = ((got_address + got_offset)
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- (plt_address + plt_offset + 8));
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if (offset < 0 || offset > 0x0fffffff)
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gold_error(_("PLT offset too large, try linking with --long-plt"));
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uint32_t plt_insn0 = plt_entry[0] | ((offset >> 20) & 0xff);
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elfcpp::Swap<32, big_endian>::writeval(pov, plt_insn0);
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uint32_t plt_insn1 = plt_entry[1] | ((offset >> 12) & 0xff);
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elfcpp::Swap<32, big_endian>::writeval(pov + 4, plt_insn1);
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uint32_t plt_insn2 = plt_entry[2] | (offset & 0xfff);
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elfcpp::Swap<32, big_endian>::writeval(pov + 8, plt_insn2);
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}
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// This class generates long (16-byte) entries, for arbitrary displacements.
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template<bool big_endian>
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class Output_data_plt_arm_long : public Output_data_plt_arm_standard<big_endian>
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{
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public:
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Output_data_plt_arm_long(Layout* layout,
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Arm_output_data_got<big_endian>* got,
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Output_data_space* got_plt,
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Output_data_space* got_irelative)
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: Output_data_plt_arm_standard<big_endian>(layout, got, got_plt, got_irelative)
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{ }
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protected:
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// Return the size of a PLT entry.
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virtual unsigned int
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do_get_plt_entry_size() const
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{ return sizeof(plt_entry); }
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virtual void
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do_fill_plt_entry(unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address,
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unsigned int got_offset,
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unsigned int plt_offset);
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private:
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// Template for subsequent PLT entries.
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static const uint32_t plt_entry[4];
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};
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template<bool big_endian>
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const uint32_t Output_data_plt_arm_long<big_endian>::plt_entry[4] =
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{
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0xe28fc200, // add ip, pc, #0xN0000000
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0xe28cc600, // add ip, ip, #0xNN00000
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0xe28cca00, // add ip, ip, #0xNN000
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0xe5bcf000, // ldr pc, [ip, #0xNNN]!
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};
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template<bool big_endian>
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void
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Output_data_plt_arm_long<big_endian>::do_fill_plt_entry(
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unsigned char* pov,
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Arm_address got_address,
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Arm_address plt_address,
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@ -7795,13 +7879,14 @@ Output_data_plt_arm_standard<big_endian>::do_fill_plt_entry(
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int32_t offset = ((got_address + got_offset)
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- (plt_address + plt_offset + 8));
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gold_assert(offset >= 0 && offset < 0x0fffffff);
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uint32_t plt_insn0 = plt_entry[0] | ((offset >> 20) & 0xff);
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uint32_t plt_insn0 = plt_entry[0] | (offset >> 28);
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elfcpp::Swap<32, big_endian>::writeval(pov, plt_insn0);
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uint32_t plt_insn1 = plt_entry[1] | ((offset >> 12) & 0xff);
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uint32_t plt_insn1 = plt_entry[1] | ((offset >> 20) & 0xff);
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elfcpp::Swap<32, big_endian>::writeval(pov + 4, plt_insn1);
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uint32_t plt_insn2 = plt_entry[2] | (offset & 0xfff);
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uint32_t plt_insn2 = plt_entry[2] | ((offset >> 12) & 0xff);
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elfcpp::Swap<32, big_endian>::writeval(pov + 8, plt_insn2);
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uint32_t plt_insn3 = plt_entry[3] | (offset & 0xfff);
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elfcpp::Swap<32, big_endian>::writeval(pov + 12, plt_insn3);
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}
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// Write out the PLT. This uses the hand-coded instructions above,
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@ -834,6 +834,10 @@ class General_options
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"veneer"),
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NULL);
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DEFINE_bool(long_plt, options::TWO_DASHES, '\0', false,
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N_("(ARM only) Generate long PLT entries"),
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N_("(ARM only) Do not generate long PLT entries"));
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DEFINE_bool(g, options::EXACTLY_ONE_DASH, '\0', false,
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N_("Ignored"), NULL);
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