Description
System.Reflection.Metadata exposes an api (System.Reflection.PortableExecutable.ManagedPEBuilder.MappedFieldDataAlignment) which is supposed to represent the alignment that the MappedFieldData elements are held at. That value is a constant with a value of 8. However, the mapped field data is actually not reliably 8 byte aligned. Instead it appears to be 4 byte aligned. Reliable alignment behavior is necessary to allow Roslyn to properly align data from the upcoming CreateSpan<T> feature.
Reproduction Steps
Build a C# binary from the following source, and compile with various different compile options (64bit vs 32bit, debug vs release, etc.)
using System;
Console.WriteLine("🌄");
class C {
ReadOnlySpan<byte> M() {
return new byte[] { 1, 2, 3 };
}
uint[] N() {
return new uint[] { 1, 2, 3 };
}
}
Expected behavior
Examine the binary with ildasm, and note that the first field rva's is not reliably aligned at an 8 byte boundary.
Actual behavior
Depending on the particular flags used to the compiler, the first field may only be 4 byte aligned.
Regression?
No
Known Workarounds
No response
Configuration
No response
Other information
No response
Description
System.Reflection.Metadata exposes an api (
System.Reflection.PortableExecutable.ManagedPEBuilder.MappedFieldDataAlignment) which is supposed to represent the alignment that the MappedFieldData elements are held at. That value is a constant with a value of 8. However, the mapped field data is actually not reliably 8 byte aligned. Instead it appears to be 4 byte aligned. Reliable alignment behavior is necessary to allow Roslyn to properly align data from the upcomingCreateSpan<T>feature.Reproduction Steps
Build a C# binary from the following source, and compile with various different compile options (64bit vs 32bit, debug vs release, etc.)
Expected behavior
Examine the binary with ildasm, and note that the first field rva's is not reliably aligned at an 8 byte boundary.
Actual behavior
Depending on the particular flags used to the compiler, the first field may only be 4 byte aligned.
Regression?
No
Known Workarounds
No response
Configuration
No response
Other information
No response