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Fix RVA field alignment #60

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Merged
merged 3 commits into from
Jan 10, 2023
Merged

Fix RVA field alignment #60

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a588c2e
Fix RVA field alignment
sbomer Dec 21, 2022
877075a
Keep alignment values for code
sbomer Jan 9, 2023
df9b0ad
Merge branch 'main' into fixAlignment
sbomer Jan 10, 2023
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2 changes: 1 addition & 1 deletion Mono.Cecil.Cil/CodeWriter.cs
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Expand Up @@ -32,7 +32,7 @@ sealed class CodeWriter : ByteBuffer {
public CodeWriter (MetadataBuilder metadata)
: base (0)
{
this.code_base = metadata.text_map.GetNextRVA (TextSegment.CLIHeader);
this.code_base = metadata.text_map.GetRVA (TextSegment.Code);
this.metadata = metadata;
this.standalone_signatures = new Dictionary<uint, MetadataToken> ();
this.tiny_method_bodies = new Dictionary<ByteBuffer, RVA> (new ByteBufferEqualityComparer ());
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5 changes: 5 additions & 0 deletions Mono.Cecil/AssemblyWriter.cs
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Expand Up @@ -987,6 +987,11 @@ TextMap CreateTextMap ()
var map = new TextMap ();
map.AddMap (TextSegment.ImportAddressTable, module.Architecture == TargetArchitecture.I386 ? 8 : 0);
map.AddMap (TextSegment.CLIHeader, 0x48, 8);
var pe64 = module.Architecture == TargetArchitecture.AMD64 || module.Architecture == TargetArchitecture.IA64 || module.Architecture == TargetArchitecture.ARM64;
// Alignment of the code segment must be set before the code is written
// These alignment values are probably not necessary, but are being left in
// for now in case something requires them.
map.AddMap (TextSegment.Code, 0, !pe64 ? 4 : 16);
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This does not look right to me. The AnyCPU binaries can run on 64-bit architectures and this is not going to guarantee sufficient alignment for them,

For example, consider static ReadOnlySpan<long> MySpan => new long[] { 1, 2, 3, 6, 7 };. The backing RVA field needs to have 8-byte alignment in this case.

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Ah ok, this extra alignment applies to IL code only (and it should not be needed it in the first place). The RVA alignment is handled elsewhere.

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We went back and forth on changing the code alignment, but eventually decided to keep the original logic.

return map;
}

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