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This repository was archived by the owner on May 28, 2025. It is now read-only.
/rustPublic archive
forked fromrust-lang/rust

Commitfbe38ea

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Unrolled build forrust-lang#127792
Rollup merge ofrust-lang#127792 - workingjubilee:read-unaligned-is-dwarfier, r=joboetstd: Use `read_unaligned` for reads from DWARFThere's a lot of... *stuff* going on here. Meanwhile, `read_unaligned` has been available since 1.17.0, so let's just use that.
2 parents1a6e777 +2499057 commitfbe38ea

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1 file changed

+12
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lines changed
  • library/std/src/sys/personality/dwarf

1 file changed

+12
-14
lines changed

‎library/std/src/sys/personality/dwarf/mod.rs‎

Lines changed: 12 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -17,32 +17,30 @@ pub struct DwarfReader {
1717
pubptr:*constu8,
1818
}
1919

20-
#[repr(C, packed)]
21-
structUnaligned<T>(T);
22-
20+
#[forbid(unsafe_op_in_unsafe_fn)]
2321
implDwarfReader{
2422
pubfnnew(ptr:*constu8) ->DwarfReader{
2523
DwarfReader{ ptr}
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}
2725

28-
// DWARF streams are packed, so e.g., a u32 would not necessarily be aligned
29-
// on a 4-byte boundary. This may cause problems on platforms with strict
30-
// alignment requirements. By wrapping data in a "packed" struct, we are
31-
// telling the backend to generate "misalignment-safe" code.
26+
/// Read a type T and then bump the pointer by that amount.
27+
///
28+
/// DWARF streams are "packed", so all types must be read at align 1.
3229
pubunsafefnread<T:Copy>(&mutself) ->T{
33-
letUnaligned(result) =*(self.ptras*constUnaligned<T>);
34-
self.ptr =self.ptr.add(mem::size_of::<T>());
35-
result
30+
unsafe{
31+
let result =self.ptr.cast::<T>().read_unaligned();
32+
self.ptr =self.ptr.byte_add(mem::size_of::<T>());
33+
result
34+
}
3635
}
3736

38-
// ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable
39-
// Length Data".
37+
/// ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable Length Data".
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pubunsafefnread_uleb128(&mutself) ->u64{
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letmut shift:usize =0;
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letmut result:u64 =0;
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letmut byte:u8;
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loop{
45-
byte =self.read::<u8>();
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byte =unsafe{self.read::<u8>()};
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result |=((byte&0x7F)asu64) << shift;
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shift +=7;
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if byte&0x80 ==0{
@@ -57,7 +55,7 @@ impl DwarfReader {
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letmut result:u64 =0;
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letmut byte:u8;
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loop{
60-
byte =self.read::<u8>();
58+
byte =unsafe{self.read::<u8>()};
6159
result |=((byte&0x7F)asu64) << shift;
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shift +=7;
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if byte&0x80 ==0{

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