Index: third_party/libc++abi/include/mach-o/compact_unwind_encoding.h |
=================================================================== |
--- third_party/libc++abi/include/mach-o/compact_unwind_encoding.h (revision 0) |
+++ third_party/libc++abi/include/mach-o/compact_unwind_encoding.h (revision 0) |
@@ -0,0 +1,487 @@ |
+//===------------------ mach-o/compact_unwind_encoding.h ------------------===// |
+// |
+// The LLVM Compiler Infrastructure |
+// |
+// This file is dual licensed under the MIT and the University of Illinois Open |
+// Source Licenses. See LICENSE.TXT for details. |
+// |
+// |
+// Darwin's alternative to dwarf based unwind encodings. |
+// |
+//===----------------------------------------------------------------------===// |
+ |
+ |
+#ifndef __COMPACT_UNWIND_ENCODING__ |
+#define __COMPACT_UNWIND_ENCODING__ |
+ |
+#include <stdint.h> |
+ |
+// |
+// Compilers can emit standard Dwarf FDEs in the __TEXT,__eh_frame section |
+// of object files. Or compilers can emit compact unwind information in |
+// the __LD,__compact_unwind section. |
+// |
+// When the linker creates a final linked image, it will create a |
+// __TEXT,__unwind_info section. This section is a small and fast way for the |
+// runtime to access unwind info for any given function. If the compiler |
+// emitted compact unwind info for the function, that compact unwind info will |
+// be encoded in the __TEXT,__unwind_info section. If the compiler emitted |
+// dwarf unwind info, the __TEXT,__unwind_info section will contain the offset |
+// of the FDE in the __TEXT,__eh_frame section in the final linked image. |
+// |
+// Note: Previously, the linker would transform some dwarf unwind infos into |
+// compact unwind info. But that is fragile and no longer done. |
+ |
+ |
+// |
+// The compact unwind endoding is a 32-bit value which encoded in an |
+// architecture specific way, which registers to restore from where, and how |
+// to unwind out of the function. |
+// |
+typedef uint32_t compact_unwind_encoding_t; |
+ |
+ |
+// architecture independent bits |
+enum { |
+ UNWIND_IS_NOT_FUNCTION_START = 0x80000000, |
+ UNWIND_HAS_LSDA = 0x40000000, |
+ UNWIND_PERSONALITY_MASK = 0x30000000, |
+}; |
+ |
+ |
+ |
+ |
+// |
+// x86 |
+// |
+// 1-bit: start |
+// 1-bit: has lsda |
+// 2-bit: personality index |
+// |
+// 4-bits: 0=old, 1=ebp based, 2=stack-imm, 3=stack-ind, 4=dwarf |
+// ebp based: |
+// 15-bits (5*3-bits per reg) register permutation |
+// 8-bits for stack offset |
+// frameless: |
+// 8-bits stack size |
+// 3-bits stack adjust |
+// 3-bits register count |
+// 10-bits register permutation |
+// |
+enum { |
+ UNWIND_X86_MODE_MASK = 0x0F000000, |
+ UNWIND_X86_MODE_EBP_FRAME = 0x01000000, |
+ UNWIND_X86_MODE_STACK_IMMD = 0x02000000, |
+ UNWIND_X86_MODE_STACK_IND = 0x03000000, |
+ UNWIND_X86_MODE_DWARF = 0x04000000, |
+ |
+ UNWIND_X86_EBP_FRAME_REGISTERS = 0x00007FFF, |
+ UNWIND_X86_EBP_FRAME_OFFSET = 0x00FF0000, |
+ |
+ UNWIND_X86_FRAMELESS_STACK_SIZE = 0x00FF0000, |
+ UNWIND_X86_FRAMELESS_STACK_ADJUST = 0x0000E000, |
+ UNWIND_X86_FRAMELESS_STACK_REG_COUNT = 0x00001C00, |
+ UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION = 0x000003FF, |
+ |
+ UNWIND_X86_DWARF_SECTION_OFFSET = 0x00FFFFFF, |
+}; |
+ |
+enum { |
+ UNWIND_X86_REG_NONE = 0, |
+ UNWIND_X86_REG_EBX = 1, |
+ UNWIND_X86_REG_ECX = 2, |
+ UNWIND_X86_REG_EDX = 3, |
+ UNWIND_X86_REG_EDI = 4, |
+ UNWIND_X86_REG_ESI = 5, |
+ UNWIND_X86_REG_EBP = 6, |
+}; |
+ |
+// |
+// For x86 there are four modes for the compact unwind encoding: |
+// UNWIND_X86_MODE_EBP_FRAME: |
+// EBP based frame where EBP is push on stack immediately after return address, |
+// then ESP is moved to EBP. Thus, to unwind ESP is restored with the current |
+// EPB value, then EBP is restored by popping off the stack, and the return |
+// is done by popping the stack once more into the pc. |
+// All non-volatile registers that need to be restored must have been saved |
+// in a small range in the stack that starts EBP-4 to EBP-1020. The offset/4 |
+// is encoded in the UNWIND_X86_EBP_FRAME_OFFSET bits. The registers saved |
+// are encoded in the UNWIND_X86_EBP_FRAME_REGISTERS bits as five 3-bit entries. |
+// Each entry contains which register to restore. |
+// UNWIND_X86_MODE_STACK_IMMD: |
+// A "frameless" (EBP not used as frame pointer) function with a small |
+// constant stack size. To return, a constant (encoded in the compact |
+// unwind encoding) is added to the ESP. Then the return is done by |
+// popping the stack into the pc. |
+// All non-volatile registers that need to be restored must have been saved |
+// on the stack immediately after the return address. The stack_size/4 is |
+// encoded in the UNWIND_X86_FRAMELESS_STACK_SIZE (max stack size is 1024). |
+// The number of registers saved is encoded in UNWIND_X86_FRAMELESS_STACK_REG_COUNT. |
+// UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION constains which registers were |
+// saved and their order. |
+// UNWIND_X86_MODE_STACK_IND: |
+// A "frameless" (EBP not used as frame pointer) function large constant |
+// stack size. This case is like the previous, except the stack size is too |
+// large to encode in the compact unwind encoding. Instead it requires that |
+// the function contains "subl $nnnnnnnn,ESP" in its prolog. The compact |
+// encoding contains the offset to the nnnnnnnn value in the function in |
+// UNWIND_X86_FRAMELESS_STACK_SIZE. |
+// UNWIND_X86_MODE_DWARF: |
+// No compact unwind encoding is available. Instead the low 24-bits of the |
+// compact encoding is the offset of the dwarf FDE in the __eh_frame section. |
+// This mode is never used in object files. It is only generated by the |
+// linker in final linked images which have only dwarf unwind info for a |
+// function. |
+// |
+// The following is the algorithm used to create the permutation encoding used |
+// with frameless stacks. It is passed the number of registers to be saved and |
+// an array of the register numbers saved. |
+// |
+//uint32_t permute_encode(uint32_t registerCount, const uint32_t registers[6]) |
+//{ |
+// uint32_t renumregs[6]; |
+// for (int i=6-registerCount; i < 6; ++i) { |
+// int countless = 0; |
+// for (int j=6-registerCount; j < i; ++j) { |
+// if ( registers[j] < registers[i] ) |
+// ++countless; |
+// } |
+// renumregs[i] = registers[i] - countless -1; |
+// } |
+// uint32_t permutationEncoding = 0; |
+// switch ( registerCount ) { |
+// case 6: |
+// permutationEncoding |= (120*renumregs[0] + 24*renumregs[1] |
+// + 6*renumregs[2] + 2*renumregs[3] |
+// + renumregs[4]); |
+// break; |
+// case 5: |
+// permutationEncoding |= (120*renumregs[1] + 24*renumregs[2] |
+// + 6*renumregs[3] + 2*renumregs[4] |
+// + renumregs[5]); |
+// break; |
+// case 4: |
+// permutationEncoding |= (60*renumregs[2] + 12*renumregs[3] |
+// + 3*renumregs[4] + renumregs[5]); |
+// break; |
+// case 3: |
+// permutationEncoding |= (20*renumregs[3] + 4*renumregs[4] |
+// + renumregs[5]); |
+// break; |
+// case 2: |
+// permutationEncoding |= (5*renumregs[4] + renumregs[5]); |
+// break; |
+// case 1: |
+// permutationEncoding |= (renumregs[5]); |
+// break; |
+// } |
+// return permutationEncoding; |
+//} |
+// |
+ |
+ |
+ |
+ |
+// |
+// x86_64 |
+// |
+// 1-bit: start |
+// 1-bit: has lsda |
+// 2-bit: personality index |
+// |
+// 4-bits: 0=old, 1=rbp based, 2=stack-imm, 3=stack-ind, 4=dwarf |
+// rbp based: |
+// 15-bits (5*3-bits per reg) register permutation |
+// 8-bits for stack offset |
+// frameless: |
+// 8-bits stack size |
+// 3-bits stack adjust |
+// 3-bits register count |
+// 10-bits register permutation |
+// |
+enum { |
+ UNWIND_X86_64_MODE_MASK = 0x0F000000, |
+ UNWIND_X86_64_MODE_RBP_FRAME = 0x01000000, |
+ UNWIND_X86_64_MODE_STACK_IMMD = 0x02000000, |
+ UNWIND_X86_64_MODE_STACK_IND = 0x03000000, |
+ UNWIND_X86_64_MODE_DWARF = 0x04000000, |
+ |
+ UNWIND_X86_64_RBP_FRAME_REGISTERS = 0x00007FFF, |
+ UNWIND_X86_64_RBP_FRAME_OFFSET = 0x00FF0000, |
+ |
+ UNWIND_X86_64_FRAMELESS_STACK_SIZE = 0x00FF0000, |
+ UNWIND_X86_64_FRAMELESS_STACK_ADJUST = 0x0000E000, |
+ UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT = 0x00001C00, |
+ UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION = 0x000003FF, |
+ |
+ UNWIND_X86_64_DWARF_SECTION_OFFSET = 0x00FFFFFF, |
+}; |
+ |
+enum { |
+ UNWIND_X86_64_REG_NONE = 0, |
+ UNWIND_X86_64_REG_RBX = 1, |
+ UNWIND_X86_64_REG_R12 = 2, |
+ UNWIND_X86_64_REG_R13 = 3, |
+ UNWIND_X86_64_REG_R14 = 4, |
+ UNWIND_X86_64_REG_R15 = 5, |
+ UNWIND_X86_64_REG_RBP = 6, |
+}; |
+// |
+// For x86_64 there are four modes for the compact unwind encoding: |
+// UNWIND_X86_64_MODE_RBP_FRAME: |
+// RBP based frame where RBP is push on stack immediately after return address, |
+// then RSP is moved to RBP. Thus, to unwind RSP is restored with the current |
+// EPB value, then RBP is restored by popping off the stack, and the return |
+// is done by popping the stack once more into the pc. |
+// All non-volatile registers that need to be restored must have been saved |
+// in a small range in the stack that starts RBP-8 to RBP-1020. The offset/4 |
+// is encoded in the UNWIND_X86_64_RBP_FRAME_OFFSET bits. The registers saved |
+// are encoded in the UNWIND_X86_64_RBP_FRAME_REGISTERS bits as five 3-bit entries. |
+// Each entry contains which register to restore. |
+// UNWIND_X86_64_MODE_STACK_IMMD: |
+// A "frameless" (RBP not used as frame pointer) function with a small |
+// constant stack size. To return, a constant (encoded in the compact |
+// unwind encoding) is added to the RSP. Then the return is done by |
+// popping the stack into the pc. |
+// All non-volatile registers that need to be restored must have been saved |
+// on the stack immediately after the return address. The stack_size/4 is |
+// encoded in the UNWIND_X86_64_FRAMELESS_STACK_SIZE (max stack size is 1024). |
+// The number of registers saved is encoded in UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT. |
+// UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION constains which registers were |
+// saved and their order. |
+// UNWIND_X86_64_MODE_STACK_IND: |
+// A "frameless" (RBP not used as frame pointer) function large constant |
+// stack size. This case is like the previous, except the stack size is too |
+// large to encode in the compact unwind encoding. Instead it requires that |
+// the function contains "subq $nnnnnnnn,RSP" in its prolog. The compact |
+// encoding contains the offset to the nnnnnnnn value in the function in |
+// UNWIND_X86_64_FRAMELESS_STACK_SIZE. |
+// UNWIND_X86_64_MODE_DWARF: |
+// No compact unwind encoding is available. Instead the low 24-bits of the |
+// compact encoding is the offset of the dwarf FDE in the __eh_frame section. |
+// This mode is never used in object files. It is only generated by the |
+// linker in final linked images which have only dwarf unwind info for a |
+// function. |
+// |
+ |
+ |
+#ifndef __OPEN_SOURCE__ |
+ |
+// ARM64 |
+// |
+// 1-bit: start |
+// 1-bit: has lsda |
+// 2-bit: personality index |
+// |
+// 4-bits: 4=frame-based, 2=frameless, 3=dwarf |
+// frameless: |
+// 12-bits of stack size |
+// frame-based: |
+// 4-bits D reg pairs saved |
+// 5-bits X reg pairs saved |
+// dwarf: |
+// 24-bits offset of dwarf FDE in __eh_frame section |
+// |
+enum { |
+ UNWIND_ARM64_MODE_MASK = 0x0F000000, |
+ UNWIND_ARM64_MODE_FRAMELESS = 0x02000000, |
+ UNWIND_ARM64_MODE_DWARF = 0x03000000, |
+ UNWIND_ARM64_MODE_FRAME = 0x04000000, |
+ |
+ UNWIND_ARM64_FRAME_X19_X20_PAIR = 0x00000001, |
+ UNWIND_ARM64_FRAME_X21_X22_PAIR = 0x00000002, |
+ UNWIND_ARM64_FRAME_X23_X24_PAIR = 0x00000004, |
+ UNWIND_ARM64_FRAME_X25_X26_PAIR = 0x00000008, |
+ UNWIND_ARM64_FRAME_X27_X28_PAIR = 0x00000010, |
+ UNWIND_ARM64_FRAME_D8_D9_PAIR = 0x00000100, |
+ UNWIND_ARM64_FRAME_D10_D11_PAIR = 0x00000200, |
+ UNWIND_ARM64_FRAME_D12_D13_PAIR = 0x00000400, |
+ UNWIND_ARM64_FRAME_D14_D15_PAIR = 0x00000800, |
+ |
+ UNWIND_ARM64_FRAME_X21_X22_PAIR_OLD = 0x00000001, |
+ UNWIND_ARM64_FRAME_X23_X24_PAIR_OLD = 0x00000002, |
+ UNWIND_ARM64_FRAME_X25_X26_PAIR_OLD = 0x00000004, |
+ UNWIND_ARM64_FRAME_X27_X28_PAIR_OLD = 0x00000008, |
+ UNWIND_ARM64_FRAME_D8_D9_PAIR_OLD = 0x00000010, |
+ UNWIND_ARM64_FRAME_D10_D11_PAIR_OLD = 0x00000020, |
+ UNWIND_ARM64_FRAME_D12_D13_PAIR_OLD = 0x00000040, |
+ UNWIND_ARM64_FRAME_D14_D15_PAIR_OLD = 0x00000080, |
+ |
+ UNWIND_ARM64_FRAMELESS_STACK_SIZE_MASK = 0x00FFF000, |
+ UNWIND_ARM64_DWARF_SECTION_OFFSET = 0x00FFFFFF, |
+}; |
+// For arm64 there are three modes for the compact unwind encoding: |
+// UNWIND_ARM64_MODE_FRAME: |
+// This is a standard arm64 prolog where FP/LR are immediately pushed on the |
+// stack, then SP is copied to FP. If there are any non-volatile registers |
+// saved, then are copied into the stack frame in pairs in a contiguous |
+// range right below the saved FP/LR pair. Any subset of the five X pairs |
+// and four D pairs can be saved, but the memory layout must be in register |
+// number order. |
+// UNWIND_ARM64_MODE_FRAMELESS: |
+// A "frameless" leaf function, where FP/LR are not saved. The return address |
+// remains in LR throughout the function. If any non-volatile registers |
+// are saved, they must be pushed onto the stack before any stack space is |
+// allocated for local variables. The stack sized (including any saved |
+// non-volatile registers) divided by 16 is encoded in the bits |
+// UNWIND_ARM64_FRAMELESS_STACK_SIZE_MASK. |
+// UNWIND_ARM64_MODE_DWARF: |
+// No compact unwind encoding is available. Instead the low 24-bits of the |
+// compact encoding is the offset of the dwarf FDE in the __eh_frame section. |
+// This mode is never used in object files. It is only generated by the |
+// linker in final linked images which have only dwarf unwind info for a |
+// function. |
+// |
+ |
+#endif // __OPEN_SOURCE__ |
+ |
+ |
+ |
+ |
+ |
+//////////////////////////////////////////////////////////////////////////////// |
+// |
+// Relocatable Object Files: __LD,__compact_unwind |
+// |
+//////////////////////////////////////////////////////////////////////////////// |
+ |
+// |
+// A compiler can generated compact unwind information for a function by adding |
+// a "row" to the __LD,__compact_unwind section. This section has the |
+// S_ATTR_DEBUG bit set, so the section will be ignored by older linkers. |
+// It is removed by the new linker, so never ends up in final executables. |
+// This section is a table, initially with one row per function (that needs |
+// unwind info). The table columns and some conceptual entries are: |
+// |
+// range-start pointer to start of function/range |
+// range-length |
+// compact-unwind-encoding 32-bit encoding |
+// personality-function or zero if no personality function |
+// lsda or zero if no LSDA data |
+// |
+// The length and encoding fields are 32-bits. The other are all pointer sized. |
+// |
+// In x86_64 assembly, these entry would look like: |
+// |
+// .section __LD,__compact_unwind,regular,debug |
+// |
+// #compact unwind for _foo |
+// .quad _foo |
+// .set L1,LfooEnd-_foo |
+// .long L1 |
+// .long 0x01010001 |
+// .quad 0 |
+// .quad 0 |
+// |
+// #compact unwind for _bar |
+// .quad _bar |
+// .set L2,LbarEnd-_bar |
+// .long L2 |
+// .long 0x01020011 |
+// .quad __gxx_personality |
+// .quad except_tab1 |
+// |
+// |
+// Notes: There is no need for any labels in the the __compact_unwind section. |
+// The use of the .set directive is to force the evaluation of the |
+// range-length at assembly time, instead of generating relocations. |
+// |
+// To support future compiler optimizations where which non-volatile registers |
+// are saved changes within a function (e.g. delay saving non-volatiles until |
+// necessary), there can by multiple lines in the __compact_unwind table for one |
+// function, each with a different (non-overlapping) range and each with |
+// different compact unwind encodings that correspond to the non-volatiles |
+// saved at that range of the function. |
+// |
+// If a particular function is so wacky that there is no compact unwind way |
+// to encode it, then the compiler can emit traditional dwarf unwind info. |
+// The runtime will use which ever is available. |
+// |
+// Runtime support for compact unwind encodings are only available on 10.6 |
+// and later. So, the compiler should not generate it when targeting pre-10.6. |
+ |
+ |
+ |
+ |
+//////////////////////////////////////////////////////////////////////////////// |
+// |
+// Final Linked Images: __TEXT,__unwind_info |
+// |
+//////////////////////////////////////////////////////////////////////////////// |
+ |
+// |
+// The __TEXT,__unwind_info section is laid out for an efficient two level lookup. |
+// The header of the section contains a coarse index that maps function address |
+// to the page (4096 byte block) containing the unwind info for that function. |
+// |
+ |
+#define UNWIND_SECTION_VERSION 1 |
+struct unwind_info_section_header |
+{ |
+ uint32_t version; // UNWIND_SECTION_VERSION |
+ uint32_t commonEncodingsArraySectionOffset; |
+ uint32_t commonEncodingsArrayCount; |
+ uint32_t personalityArraySectionOffset; |
+ uint32_t personalityArrayCount; |
+ uint32_t indexSectionOffset; |
+ uint32_t indexCount; |
+ // compact_unwind_encoding_t[] |
+ // uintptr_t personalities[] |
+ // unwind_info_section_header_index_entry[] |
+ // unwind_info_section_header_lsda_index_entry[] |
+}; |
+ |
+struct unwind_info_section_header_index_entry |
+{ |
+ uint32_t functionOffset; |
+ uint32_t secondLevelPagesSectionOffset; // section offset to start of regular or compress page |
+ uint32_t lsdaIndexArraySectionOffset; // section offset to start of lsda_index array for this range |
+}; |
+ |
+struct unwind_info_section_header_lsda_index_entry |
+{ |
+ uint32_t functionOffset; |
+ uint32_t lsdaOffset; |
+}; |
+ |
+// |
+// 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 |
+ |
Property changes on: third_party/libc++abi/include/mach-o/compact_unwind_encoding.h |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |