| //! Utilities for parsing DWARF-encoded data streams. |
| //! See <http://www.dwarfstd.org>, |
| //! DWARF-4 standard, Section 7 - "Data Representation" |
| |
| // This module is used only by x86_64-pc-windows-gnu for now, but we |
| // are compiling it everywhere to avoid regressions. |
| #![allow(unused)] |
| |
| pub mod eh; |
| |
| use core::mem; |
| |
| pub struct DwarfReader { |
| pub ptr: *const u8, |
| } |
| |
| #[repr(C, packed)] |
| struct Unaligned<T>(T); |
| |
| impl DwarfReader { |
| pub fn new(ptr: *const u8) -> DwarfReader { |
| DwarfReader { ptr } |
| } |
| |
| // DWARF streams are packed, so e.g., a u32 would not necessarily be aligned |
| // on a 4-byte boundary. This may cause problems on platforms with strict |
| // alignment requirements. By wrapping data in a "packed" struct, we are |
| // telling the backend to generate "misalignment-safe" code. |
| pub unsafe fn read<T: Copy>(&mut self) -> T { |
| let Unaligned(result) = *(self.ptr as *const Unaligned<T>); |
| self.ptr = self.ptr.add(mem::size_of::<T>()); |
| result |
| } |
| |
| // ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable |
| // Length Data". |
| pub unsafe fn read_uleb128(&mut self) -> u64 { |
| let mut shift: usize = 0; |
| let mut result: u64 = 0; |
| let mut byte: u8; |
| loop { |
| byte = self.read::<u8>(); |
| result |= ((byte & 0x7F) as u64) << shift; |
| shift += 7; |
| if byte & 0x80 == 0 { |
| break; |
| } |
| } |
| result |
| } |
| |
| pub unsafe fn read_sleb128(&mut self) -> i64 { |
| let mut shift: usize = 0; |
| let mut result: u64 = 0; |
| let mut byte: u8; |
| loop { |
| byte = self.read::<u8>(); |
| result |= ((byte & 0x7F) as u64) << shift; |
| shift += 7; |
| if byte & 0x80 == 0 { |
| break; |
| } |
| } |
| // sign-extend |
| if shift < 8 * mem::size_of::<u64>() && (byte & 0x40) != 0 { |
| result |= (!0 as u64) << shift; |
| } |
| result as i64 |
| } |
| } |