84a2b56c53
* This release contains bug-fixes for the LLVM 19.1.0 release.
This release is API and ABI compatible with 19.1.0.
- Rebase llvm-do-not-install-static-libraries.patch.
OBS-URL: https://build.opensuse.org/package/show/devel:tools:compiler/llvm19?expand=0&rev=15
478 lines
19 KiB
C
478 lines
19 KiB
C
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//
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// Darwin's alternative to DWARF based unwind encodings.
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//
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//===----------------------------------------------------------------------===//
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#ifndef __COMPACT_UNWIND_ENCODING__
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#define __COMPACT_UNWIND_ENCODING__
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#include <stdint.h>
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//
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// Compilers can emit standard DWARF FDEs in the __TEXT,__eh_frame section
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// of object files. Or compilers can emit compact unwind information in
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// the __LD,__compact_unwind section.
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//
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// When the linker creates a final linked image, it will create a
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// __TEXT,__unwind_info section. This section is a small and fast way for the
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// runtime to access unwind info for any given function. If the compiler
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// emitted compact unwind info for the function, that compact unwind info will
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// be encoded in the __TEXT,__unwind_info section. If the compiler emitted
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// DWARF unwind info, the __TEXT,__unwind_info section will contain the offset
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// of the FDE in the __TEXT,__eh_frame section in the final linked image.
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//
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// Note: Previously, the linker would transform some DWARF unwind infos into
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// compact unwind info. But that is fragile and no longer done.
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//
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// The compact unwind encoding is a 32-bit value which encoded in an
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// architecture specific way, which registers to restore from where, and how
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// to unwind out of the function.
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//
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typedef uint32_t compact_unwind_encoding_t;
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// architecture independent bits
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enum {
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UNWIND_IS_NOT_FUNCTION_START = 0x80000000,
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UNWIND_HAS_LSDA = 0x40000000,
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UNWIND_PERSONALITY_MASK = 0x30000000,
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};
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//
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// x86
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//
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// 1-bit: start
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// 1-bit: has lsda
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// 2-bit: personality index
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//
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// 4-bits: 0=old, 1=ebp based, 2=stack-imm, 3=stack-ind, 4=DWARF
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// ebp based:
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// 15-bits (5*3-bits per reg) register permutation
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// 8-bits for stack offset
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// frameless:
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// 8-bits stack size
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// 3-bits stack adjust
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// 3-bits register count
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// 10-bits register permutation
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//
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enum {
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UNWIND_X86_MODE_MASK = 0x0F000000,
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UNWIND_X86_MODE_EBP_FRAME = 0x01000000,
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UNWIND_X86_MODE_STACK_IMMD = 0x02000000,
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UNWIND_X86_MODE_STACK_IND = 0x03000000,
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UNWIND_X86_MODE_DWARF = 0x04000000,
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UNWIND_X86_EBP_FRAME_REGISTERS = 0x00007FFF,
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UNWIND_X86_EBP_FRAME_OFFSET = 0x00FF0000,
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UNWIND_X86_FRAMELESS_STACK_SIZE = 0x00FF0000,
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UNWIND_X86_FRAMELESS_STACK_ADJUST = 0x0000E000,
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UNWIND_X86_FRAMELESS_STACK_REG_COUNT = 0x00001C00,
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UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION = 0x000003FF,
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UNWIND_X86_DWARF_SECTION_OFFSET = 0x00FFFFFF,
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};
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enum {
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UNWIND_X86_REG_NONE = 0,
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UNWIND_X86_REG_EBX = 1,
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UNWIND_X86_REG_ECX = 2,
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UNWIND_X86_REG_EDX = 3,
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UNWIND_X86_REG_EDI = 4,
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UNWIND_X86_REG_ESI = 5,
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UNWIND_X86_REG_EBP = 6,
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};
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//
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// For x86 there are four modes for the compact unwind encoding:
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// UNWIND_X86_MODE_EBP_FRAME:
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// EBP based frame where EBP is push on stack immediately after return address,
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// then ESP is moved to EBP. Thus, to unwind ESP is restored with the current
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// EPB value, then EBP is restored by popping off the stack, and the return
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// is done by popping the stack once more into the pc.
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// All non-volatile registers that need to be restored must have been saved
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// in a small range in the stack that starts EBP-4 to EBP-1020. The offset/4
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// is encoded in the UNWIND_X86_EBP_FRAME_OFFSET bits. The registers saved
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// are encoded in the UNWIND_X86_EBP_FRAME_REGISTERS bits as five 3-bit entries.
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// Each entry contains which register to restore.
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// UNWIND_X86_MODE_STACK_IMMD:
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// A "frameless" (EBP not used as frame pointer) function with a small
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// constant stack size. To return, a constant (encoded in the compact
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// unwind encoding) is added to the ESP. Then the return is done by
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// popping the stack into the pc.
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// All non-volatile registers that need to be restored must have been saved
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// on the stack immediately after the return address. The stack_size/4 is
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// encoded in the UNWIND_X86_FRAMELESS_STACK_SIZE (max stack size is 1024).
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// The number of registers saved is encoded in UNWIND_X86_FRAMELESS_STACK_REG_COUNT.
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// UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION contains which registers were
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// saved and their order.
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// UNWIND_X86_MODE_STACK_IND:
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// A "frameless" (EBP not used as frame pointer) function large constant
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// stack size. This case is like the previous, except the stack size is too
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// large to encode in the compact unwind encoding. Instead it requires that
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// the function contains "subl $nnnnnnnn,ESP" in its prolog. The compact
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// encoding contains the offset to the nnnnnnnn value in the function in
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// UNWIND_X86_FRAMELESS_STACK_SIZE.
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// UNWIND_X86_MODE_DWARF:
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// No compact unwind encoding is available. Instead the low 24-bits of the
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// compact encoding is the offset of the DWARF FDE in the __eh_frame section.
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// This mode is never used in object files. It is only generated by the
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// linker in final linked images which have only DWARF unwind info for a
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// function.
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//
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// The permutation encoding is a Lehmer code sequence encoded into a
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// single variable-base number so we can encode the ordering of up to
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// six registers in a 10-bit space.
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//
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// The following is the algorithm used to create the permutation encoding used
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// with frameless stacks. It is passed the number of registers to be saved and
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// an array of the register numbers saved.
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//
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//uint32_t permute_encode(uint32_t registerCount, const uint32_t registers[6])
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//{
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// uint32_t renumregs[6];
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// for (int i=6-registerCount; i < 6; ++i) {
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// int countless = 0;
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// for (int j=6-registerCount; j < i; ++j) {
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// if ( registers[j] < registers[i] )
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// ++countless;
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// }
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// renumregs[i] = registers[i] - countless -1;
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// }
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// uint32_t permutationEncoding = 0;
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// switch ( registerCount ) {
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// case 6:
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// permutationEncoding |= (120*renumregs[0] + 24*renumregs[1]
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// + 6*renumregs[2] + 2*renumregs[3]
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// + renumregs[4]);
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// break;
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// case 5:
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// permutationEncoding |= (120*renumregs[1] + 24*renumregs[2]
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// + 6*renumregs[3] + 2*renumregs[4]
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// + renumregs[5]);
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// break;
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// case 4:
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// permutationEncoding |= (60*renumregs[2] + 12*renumregs[3]
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// + 3*renumregs[4] + renumregs[5]);
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// break;
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// case 3:
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// permutationEncoding |= (20*renumregs[3] + 4*renumregs[4]
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// + renumregs[5]);
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// break;
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// case 2:
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// permutationEncoding |= (5*renumregs[4] + renumregs[5]);
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// break;
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// case 1:
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// permutationEncoding |= (renumregs[5]);
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// break;
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// }
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// return permutationEncoding;
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//}
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//
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//
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// x86_64
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//
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// 1-bit: start
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// 1-bit: has lsda
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// 2-bit: personality index
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//
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// 4-bits: 0=old, 1=rbp based, 2=stack-imm, 3=stack-ind, 4=DWARF
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// rbp based:
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// 15-bits (5*3-bits per reg) register permutation
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// 8-bits for stack offset
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// frameless:
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// 8-bits stack size
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// 3-bits stack adjust
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// 3-bits register count
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// 10-bits register permutation
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//
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enum {
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UNWIND_X86_64_MODE_MASK = 0x0F000000,
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UNWIND_X86_64_MODE_RBP_FRAME = 0x01000000,
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UNWIND_X86_64_MODE_STACK_IMMD = 0x02000000,
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UNWIND_X86_64_MODE_STACK_IND = 0x03000000,
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UNWIND_X86_64_MODE_DWARF = 0x04000000,
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UNWIND_X86_64_RBP_FRAME_REGISTERS = 0x00007FFF,
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UNWIND_X86_64_RBP_FRAME_OFFSET = 0x00FF0000,
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UNWIND_X86_64_FRAMELESS_STACK_SIZE = 0x00FF0000,
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UNWIND_X86_64_FRAMELESS_STACK_ADJUST = 0x0000E000,
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UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT = 0x00001C00,
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UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION = 0x000003FF,
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UNWIND_X86_64_DWARF_SECTION_OFFSET = 0x00FFFFFF,
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};
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enum {
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UNWIND_X86_64_REG_NONE = 0,
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UNWIND_X86_64_REG_RBX = 1,
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UNWIND_X86_64_REG_R12 = 2,
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UNWIND_X86_64_REG_R13 = 3,
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UNWIND_X86_64_REG_R14 = 4,
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UNWIND_X86_64_REG_R15 = 5,
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UNWIND_X86_64_REG_RBP = 6,
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};
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//
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// For x86_64 there are four modes for the compact unwind encoding:
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// UNWIND_X86_64_MODE_RBP_FRAME:
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// RBP based frame where RBP is push on stack immediately after return address,
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// then RSP is moved to RBP. Thus, to unwind RSP is restored with the current
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// EPB value, then RBP is restored by popping off the stack, and the return
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// is done by popping the stack once more into the pc.
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// All non-volatile registers that need to be restored must have been saved
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// in a small range in the stack that starts RBP-8 to RBP-2040. The offset/8
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// is encoded in the UNWIND_X86_64_RBP_FRAME_OFFSET bits. The registers saved
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// are encoded in the UNWIND_X86_64_RBP_FRAME_REGISTERS bits as five 3-bit entries.
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// Each entry contains which register to restore.
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// UNWIND_X86_64_MODE_STACK_IMMD:
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// A "frameless" (RBP not used as frame pointer) function with a small
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// constant stack size. To return, a constant (encoded in the compact
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// unwind encoding) is added to the RSP. Then the return is done by
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// popping the stack into the pc.
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// All non-volatile registers that need to be restored must have been saved
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// on the stack immediately after the return address. The stack_size/8 is
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// encoded in the UNWIND_X86_64_FRAMELESS_STACK_SIZE (max stack size is 2048).
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// The number of registers saved is encoded in UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT.
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// UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION contains which registers were
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// saved and their order.
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// UNWIND_X86_64_MODE_STACK_IND:
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// A "frameless" (RBP not used as frame pointer) function large constant
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// stack size. This case is like the previous, except the stack size is too
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// large to encode in the compact unwind encoding. Instead it requires that
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// the function contains "subq $nnnnnnnn,RSP" in its prolog. The compact
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// encoding contains the offset to the nnnnnnnn value in the function in
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// UNWIND_X86_64_FRAMELESS_STACK_SIZE.
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// UNWIND_X86_64_MODE_DWARF:
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// No compact unwind encoding is available. Instead the low 24-bits of the
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// compact encoding is the offset of the DWARF FDE in the __eh_frame section.
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// This mode is never used in object files. It is only generated by the
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// linker in final linked images which have only DWARF unwind info for a
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// function.
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//
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// ARM64
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//
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// 1-bit: start
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// 1-bit: has lsda
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// 2-bit: personality index
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//
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// 4-bits: 4=frame-based, 3=DWARF, 2=frameless
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// frameless:
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// 12-bits of stack size
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// frame-based:
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// 4-bits D reg pairs saved
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// 5-bits X reg pairs saved
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// DWARF:
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// 24-bits offset of DWARF FDE in __eh_frame section
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//
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enum {
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UNWIND_ARM64_MODE_MASK = 0x0F000000,
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UNWIND_ARM64_MODE_FRAMELESS = 0x02000000,
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UNWIND_ARM64_MODE_DWARF = 0x03000000,
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UNWIND_ARM64_MODE_FRAME = 0x04000000,
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UNWIND_ARM64_FRAME_X19_X20_PAIR = 0x00000001,
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UNWIND_ARM64_FRAME_X21_X22_PAIR = 0x00000002,
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UNWIND_ARM64_FRAME_X23_X24_PAIR = 0x00000004,
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UNWIND_ARM64_FRAME_X25_X26_PAIR = 0x00000008,
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UNWIND_ARM64_FRAME_X27_X28_PAIR = 0x00000010,
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UNWIND_ARM64_FRAME_D8_D9_PAIR = 0x00000100,
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UNWIND_ARM64_FRAME_D10_D11_PAIR = 0x00000200,
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UNWIND_ARM64_FRAME_D12_D13_PAIR = 0x00000400,
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UNWIND_ARM64_FRAME_D14_D15_PAIR = 0x00000800,
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UNWIND_ARM64_FRAMELESS_STACK_SIZE_MASK = 0x00FFF000,
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UNWIND_ARM64_DWARF_SECTION_OFFSET = 0x00FFFFFF,
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};
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// For arm64 there are three modes for the compact unwind encoding:
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// UNWIND_ARM64_MODE_FRAME:
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// This is a standard arm64 prolog where FP/LR are immediately pushed on the
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// stack, then SP is copied to FP. If there are any non-volatile registers
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// saved, then are copied into the stack frame in pairs in a contiguous
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// range right below the saved FP/LR pair. Any subset of the five X pairs
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// and four D pairs can be saved, but the memory layout must be in register
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// number order.
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// UNWIND_ARM64_MODE_FRAMELESS:
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// A "frameless" leaf function, where FP/LR are not saved. The return address
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// remains in LR throughout the function. If any non-volatile registers
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// are saved, they must be pushed onto the stack before any stack space is
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// allocated for local variables. The stack sized (including any saved
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// non-volatile registers) divided by 16 is encoded in the bits
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// UNWIND_ARM64_FRAMELESS_STACK_SIZE_MASK.
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// UNWIND_ARM64_MODE_DWARF:
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// No compact unwind encoding is available. Instead the low 24-bits of the
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// compact encoding is the offset of the DWARF FDE in the __eh_frame section.
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// This mode is never used in object files. It is only generated by the
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// linker in final linked images which have only DWARF unwind info for a
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// function.
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// Relocatable Object Files: __LD,__compact_unwind
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// A compiler can generated compact unwind information for a function by adding
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// a "row" to the __LD,__compact_unwind section. This section has the
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// S_ATTR_DEBUG bit set, so the section will be ignored by older linkers.
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// It is removed by the new linker, so never ends up in final executables.
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// This section is a table, initially with one row per function (that needs
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// unwind info). The table columns and some conceptual entries are:
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//
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// range-start pointer to start of function/range
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// range-length
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// compact-unwind-encoding 32-bit encoding
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// personality-function or zero if no personality function
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// lsda or zero if no LSDA data
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//
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// The length and encoding fields are 32-bits. The other are all pointer sized.
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//
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// In x86_64 assembly, these entry would look like:
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//
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// .section __LD,__compact_unwind,regular,debug
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//
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// #compact unwind for _foo
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// .quad _foo
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// .set L1,LfooEnd-_foo
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// .long L1
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// .long 0x01010001
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// .quad 0
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// .quad 0
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//
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// #compact unwind for _bar
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// .quad _bar
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// .set L2,LbarEnd-_bar
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// .long L2
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// .long 0x01020011
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// .quad __gxx_personality
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// .quad except_tab1
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//
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//
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// Notes: There is no need for any labels in the __compact_unwind section.
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// The use of the .set directive is to force the evaluation of the
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// range-length at assembly time, instead of generating relocations.
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//
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// To support future compiler optimizations where which non-volatile registers
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// are saved changes within a function (e.g. delay saving non-volatiles until
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// necessary), there can by multiple lines in the __compact_unwind table for one
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// function, each with a different (non-overlapping) range and each with
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// different compact unwind encodings that correspond to the non-volatiles
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// saved at that range of the function.
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//
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// If a particular function is so wacky that there is no compact unwind way
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// to encode it, then the compiler can emit traditional DWARF unwind info.
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// The runtime will use which ever is available.
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//
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// Runtime support for compact unwind encodings are only available on 10.6
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// and later. So, the compiler should not generate it when targeting pre-10.6.
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////////////////////////////////////////////////////////////////////////////////
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//
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// Final Linked Images: __TEXT,__unwind_info
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// The __TEXT,__unwind_info section is laid out for an efficient two level lookup.
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// The header of the section contains a coarse index that maps function address
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// to the page (4096 byte block) containing the unwind info for that function.
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//
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#define UNWIND_SECTION_VERSION 1
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struct unwind_info_section_header
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{
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uint32_t version; // UNWIND_SECTION_VERSION
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uint32_t commonEncodingsArraySectionOffset;
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uint32_t commonEncodingsArrayCount;
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uint32_t personalityArraySectionOffset;
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uint32_t personalityArrayCount;
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uint32_t indexSectionOffset;
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uint32_t indexCount;
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// compact_unwind_encoding_t[]
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// uint32_t personalities[]
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// unwind_info_section_header_index_entry[]
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// unwind_info_section_header_lsda_index_entry[]
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};
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struct unwind_info_section_header_index_entry
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{
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uint32_t functionOffset;
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uint32_t secondLevelPagesSectionOffset; // section offset to start of regular or compress page
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uint32_t lsdaIndexArraySectionOffset; // section offset to start of lsda_index array for this range
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};
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struct unwind_info_section_header_lsda_index_entry
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{
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uint32_t functionOffset;
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uint32_t lsdaOffset;
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};
|
|
|
|
//
|
|
// There are two kinds of second level index pages: regular and compressed.
|
|
// A compressed page can hold up to 1021 entries, but it cannot be used
|
|
// if too many different encoding types are used. The regular page holds
|
|
// 511 entries.
|
|
//
|
|
|
|
struct unwind_info_regular_second_level_entry
|
|
{
|
|
uint32_t functionOffset;
|
|
compact_unwind_encoding_t encoding;
|
|
};
|
|
|
|
#define UNWIND_SECOND_LEVEL_REGULAR 2
|
|
struct unwind_info_regular_second_level_page_header
|
|
{
|
|
uint32_t kind; // UNWIND_SECOND_LEVEL_REGULAR
|
|
uint16_t entryPageOffset;
|
|
uint16_t entryCount;
|
|
// entry array
|
|
};
|
|
|
|
#define UNWIND_SECOND_LEVEL_COMPRESSED 3
|
|
struct unwind_info_compressed_second_level_page_header
|
|
{
|
|
uint32_t kind; // UNWIND_SECOND_LEVEL_COMPRESSED
|
|
uint16_t entryPageOffset;
|
|
uint16_t entryCount;
|
|
uint16_t encodingsPageOffset;
|
|
uint16_t encodingsCount;
|
|
// 32-bit entry array
|
|
// encodings array
|
|
};
|
|
|
|
#define UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(entry) (entry & 0x00FFFFFF)
|
|
#define UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(entry) ((entry >> 24) & 0xFF)
|
|
|
|
|
|
|
|
#endif
|
|
|