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Merged
elinor-fung merged 1 commit into from
May 28, 2025
Merged

Remove dead code in R2RPEBuilder #115953

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108 changes: 11 additions & 97 deletions src/coreclr/tools/aot/ILCompiler.ReadyToRun/ObjectWriter/R2RPEBuilder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,52 +28,11 @@ public sealed class R2RPEBuilder : PEBuilder
/// </summary>
const int RVABitsToMatchFilePos = 16;

/// <summary>
/// This structure describes how a particular section moved between the original MSIL
/// and the output PE file. It holds beginning and end RVA of the input (MSIL) section
/// and a delta between the input and output starting RVA of the section.
/// </summary>
struct SectionRVADelta
{
/// <summary>
/// Starting RVA of the section in the input MSIL PE.
/// </summary>
public readonly int StartRVA;

/// <summary>
/// End RVA (one plus the last RVA in the section) of the section in the input MSIL PE.
/// </summary>
public readonly int EndRVA;

/// <summary>
/// Starting RVA of the section in the output PE minus its starting RVA in the input MSIL.
/// </summary>
public readonly int DeltaRVA;

/// <summary>
/// Initialize the section RVA delta information.
/// </summary>
/// <param name="startRVA">Starting RVA of the section in the input MSIL</param>
/// <param name="endRVA">End RVA of the section in the input MSIL</param>
/// <param name="deltaRVA">Output RVA of the section minus input RVA of the section</param>
public SectionRVADelta(int startRVA, int endRVA, int deltaRVA)
{
StartRVA = startRVA;
EndRVA = endRVA;
DeltaRVA = deltaRVA;
}
}

/// <summary>
/// Name of the text section.
/// </summary>
public const string TextSectionName = ".text";

/// <summary>
/// Name of the initialized data section.
/// </summary>
public const string SDataSectionName = ".sdata";

/// <summary>
/// Name of the relocation section.
/// </summary>
Expand All @@ -100,13 +59,6 @@ public SectionRVADelta(int startRVA, int endRVA, int deltaRVA)
/// </summary>
private Func<RuntimeFunctionsTableNode> _getRuntimeFunctionsTable;

/// <summary>
/// For each copied section, we store its initial and end RVA in the source PE file
/// and the RVA difference between the old and new file. We use this table to relocate
/// directory entries in the PE file header.
/// </summary>
private List<SectionRVADelta> _sectionRvaDeltas;

private class SerializedSectionData
{
/// <summary>
Expand Down Expand Up @@ -194,7 +146,6 @@ public R2RPEBuilder(
{
_target = target;
_getRuntimeFunctionsTable = getRuntimeFunctionsTable;
_sectionRvaDeltas = new List<SectionRVADelta>();

_sectionBuilder = new SectionBuilder(target);

Expand All @@ -210,16 +161,13 @@ public R2RPEBuilder(
_sectionBuilder.SetDllNameForExportDirectoryTable(outputFileSimpleName);
}

if (_sectionBuilder.FindSection(R2RPEBuilder.RelocSectionName) == null)
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@elinor-fung elinor-fung May 23, 2025

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We create the section builder and add any sections above - there's no need to check if the reloc section already exists.

{
// Always inject the relocation section to the end of section list
_sectionBuilder.AddSection(
R2RPEBuilder.RelocSectionName,
SectionCharacteristics.ContainsInitializedData |
SectionCharacteristics.MemRead |
SectionCharacteristics.MemDiscardable,
PEHeaderConstants.SectionAlignment);
}
// Always inject the relocation section to the end of section list
_sectionBuilder.AddSection(
R2RPEBuilder.RelocSectionName,
SectionCharacteristics.ContainsInitializedData |
SectionCharacteristics.MemRead |
SectionCharacteristics.MemDiscardable,
PEHeaderConstants.SectionAlignment);

List<SerializedSectionData> sectionData = new List<SerializedSectionData>();
foreach (SectionInfo sectionInfo in _sectionBuilder.GetSections())
Expand Down Expand Up @@ -353,7 +301,7 @@ public void AddSections(OutputInfoBuilder outputInfoBuilder)
sizeof(int) + // SizeOfUninitializedData
sizeof(int) + // AddressOfEntryPoint
sizeof(int) + // BaseOfCode
sizeof(long); // PE32: BaseOfData (int), ImageBase (int)
sizeof(long); // PE32: BaseOfData (int), ImageBase (int)
// PE32+: ImageBase (long)
const int OffsetOfChecksum = OffsetOfSectionAlign +
sizeof(int) + // SectionAlignment
Expand All @@ -371,7 +319,7 @@ public void AddSections(OutputInfoBuilder outputInfoBuilder)
const int OffsetOfSizeOfImage = OffsetOfChecksum - 2 * sizeof(int); // SizeOfHeaders, SizeOfImage

const int SectionHeaderNameSize = 8;
const int SectionHeaderVirtualSize = SectionHeaderNameSize; // VirtualSize follows
const int SectionHeaderVirtualSize = SectionHeaderNameSize; // VirtualSize follows
const int SectionHeaderRVAOffset = SectionHeaderVirtualSize + sizeof(int); // RVA Offset follows VirtualSize + 4 bytes VirtualSize
const int SectionHeaderSizeOfRawData = SectionHeaderRVAOffset + sizeof(int); // SizeOfRawData follows RVA
const int SectionHeaderPointerToRawDataOffset = SectionHeaderSizeOfRawData + sizeof(int); // PointerToRawData immediately follows the SizeOfRawData
Expand All @@ -385,7 +333,7 @@ public void AddSections(OutputInfoBuilder outputInfoBuilder)
sizeof(int) + // PointerToRelocations
sizeof(int) + // PointerToLineNumbers
sizeof(short) + // NumberOfRelocations
sizeof(short) + // NumberOfLineNumbers
sizeof(short) + // NumberOfLineNumbers
sizeof(int); // SectionCharacteristics

/// <summary>
Expand Down Expand Up @@ -538,42 +486,8 @@ protected override PEDirectoriesBuilder GetDirectories()
size: runtimeFunctionsTable.TableSizeExcludingSentinel);
}
}

return builder;
}

/// <summary>
/// Relocate a single directory entry.
/// </summary>
/// <param name="entry">Directory entry to allocate</param>
/// <returns>Relocated directory entry</returns>
public DirectoryEntry RelocateDirectoryEntry(DirectoryEntry entry)
{
return new DirectoryEntry(RelocateRVA(entry.RelativeVirtualAddress), entry.Size);
}

/// <summary>
/// Relocate a given RVA using the section offset table produced during section serialization.
/// </summary>
/// <param name="rva">RVA to relocate</param>
/// <returns>Relocated RVA</returns>
private int RelocateRVA(int rva)
{
if (rva == 0)
{
// Zero RVA is normally used as NULL
return rva;
}
foreach (SectionRVADelta sectionRvaDelta in _sectionRvaDeltas)
{
if (rva >= sectionRvaDelta.StartRVA && rva < sectionRvaDelta.EndRVA)
{
// We found the input section holding the RVA, apply its specific delt (output RVA - input RVA).
return rva + sectionRvaDelta.DeltaRVA;
}
}
Debug.Fail("RVA is not within any of the input sections - output PE may be inconsistent");
return rva;
return builder;
}

/// <summary>
Expand Down
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