[release/9.0-preview1] [NativeAOT] ObjWriter: Fix over-alignment of .…

…eh_frame entries (#97457) * Fix over-alignment of .eh_frame entries * PR feedback --------- Co-authored-by: Filip Navara <[email protected]>
dotnet · Jan 24, 2024 · b4aa81d · b4aa81d
1 parent 37828ce
commit b4aa81d
Showing 1 changed file with 10 additions and 4 deletions.
diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/ObjectWriter/Dwarf/DwarfEhFrame.cs b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/ObjectWriter/Dwarf/DwarfEhFrame.cs
@@ -43,6 +43,11 @@ public void AddFde(in DwarfFde fde)
             WriteFde(fde, cieOffset);
         }
 
+        private static uint PaddingSize(uint length, uint alignment)
+        {
+            return ((length + alignment - 1u) & ~(alignment - 1u)) - length;
+        }
+
         private void WriteCie(DwarfCie cie)
         {
             Utf8StringBuilder augmentationString = new Utf8StringBuilder();
@@ -82,7 +87,7 @@ private void WriteCie(DwarfCie cie)
                 DwarfHelper.SizeOfULEB128(cie.ReturnAddressRegister) +
                 (uint)(augmentationLength > 0 ? DwarfHelper.SizeOfULEB128(augmentationLength) + augmentationLength : 0) +
                 (uint)cie.Instructions.Length;
-            uint padding = ((length + 7u) & ~7u) - length;
+            uint padding = PaddingSize(length, AddressSize(cie.PointerEncoding));
 
             _sectionWriter.WriteLittleEndian<uint>(length + padding - 4u);
             _sectionWriter.WriteLittleEndian<uint>(0);
@@ -122,14 +127,15 @@ private void WriteFde(in DwarfFde fde, uint cieOffset)
                     (fde.Cie.PersonalityEncoding != 0 ? AddressSize(fde.Cie.PersonalityEncoding) : 0) +
                     (fde.Cie.LsdaEncoding != 0 ? AddressSize(fde.Cie.LsdaEncoding) : 0) : 0;
 
+            uint pointerEncodingSize = AddressSize(fde.Cie.PointerEncoding);
             uint length =
                 4u + // Length
                 4u + // CIE offset
-                AddressSize(fde.Cie.PointerEncoding) + // PC start
-                AddressSize(fde.Cie.PointerEncoding) + // PC end
+                pointerEncodingSize + // PC start
+                pointerEncodingSize + // PC end
                 augmentationLength +
                 (uint)fde.Instructions.Length;
-            uint padding = ((length + 7u) & ~7u) - length;
+            uint padding = PaddingSize(length, pointerEncodingSize);
 
             _sectionWriter.WriteLittleEndian<uint>(length + padding - 4u);
             _sectionWriter.WriteLittleEndian<uint>((uint)(_sectionWriter.Position - cieOffset));