Disable compact unwinding on osx-x64, add hack to stop linker from co…

…rrupting DWARF CFI
dotnet · Sep 15, 2022 · 22a8804 · 22a8804
1 parent a9dfa2d
commit 22a8804
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Showing 3 changed files with 16 additions and 15 deletions.
diff --git a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
@@ -112,6 +112,7 @@ The .NET Foundation licenses this file to you under the MIT license.
       <LinkerArg Include="-Wl,-z,now" Condition="'$(TargetOS)' != 'OSX'" />
       <LinkerArg Include="-Wl,-u,_NativeAOT_StaticInitialization" Condition="'$(TargetOS)' == 'OSX' and '$(NativeLib)' == 'Shared'" />
       <LinkerArg Include="-Wl,--require-defined,NativeAOT_StaticInitialization" Condition="'$(TargetOS)' != 'OSX' and '$(NativeLib)' == 'Shared'" />
+      <LinkerArg Include="-Wl,-no_compact_unwind -Wl,-keep_dwarf_unwind" Condition="'$(TargetOS)' == 'OSX' and '$(TargetArchitecture)' == 'x64'" />
 
       <LinkerArg Include="@(NativeFramework->'-framework %(Identity)')" Condition="'$(TargetOS)' == 'OSX'" />
     </ItemGroup>

diff --git a/src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cpp b/src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cpp
@@ -653,26 +653,11 @@ bool UnixNativeCodeManager::GetReturnAddressHijackInfo(MethodInfo *    pMethodIn
     GcInfoDecoderFlags flags = DECODE_RETURN_KIND;
 #if defined(TARGET_ARM) || defined(TARGET_ARM64)
     flags = (GcInfoDecoderFlags)(flags | DECODE_HAS_TAILCALLS);
-#elif defined(TARGET_AMD64) && defined(TARGET_OSX)
-    flags = (GcInfoDecoderFlags)(flags | DECODE_PROLOG_LENGTH);
 #endif // TARGET_ARM || TARGET_ARM64
 
     GcInfoDecoder decoder(GCInfoToken(p), flags);
     *pRetValueKind = GetGcRefKind(decoder.GetReturnKind());
 
-#if defined(TARGET_AMD64) && defined(TARGET_OSX)
-    // Compact unwinding on macOS cannot properly handle unwinding the function prolog
-    if ((PTR_VOID)pRegisterSet->IP == pNativeMethodInfo->pMethodStartAddress)
-    {
-        *ppvRetAddrLocation = (PTR_PTR_VOID)pRegisterSet->GetSP();
-        return true;
-    }
-    else if ((PTR_UInt8)pRegisterSet->IP < (PTR_UInt8)pNativeMethodInfo->pMethodStartAddress + decoder.GetPrologSize())
-    {
-        return false;
-    }
-#endif
-
     int epilogueInstructions = TrailingEpilogueInstructionsCount((PTR_VOID)pRegisterSet->IP);
     if (epilogueInstructions < 0)
     {

diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/ObjectWriter.cs b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/ObjectWriter.cs
@@ -713,6 +713,21 @@ public void EmitCFICodes(int offset)
                     // Internal compiler error
                     Debug.Assert(false);
                 }
+
+                if (_targetPlatform.OperatingSystem == TargetOS.OSX)
+                {
+                    // Emit a symbol for beginning of the frame. This is workaround for ld64
+                    // linker bug which would produce DWARF with incorrect pcStart offsets for
+                    // exception handling blocks if there is no symbol present for them.
+                    //
+                    // To make things simple we just reuse blobSymbolName and change `_lsda`
+                    // prefix to `_fram`.
+                    blobSymbolName[1] = (byte)'f';
+                    blobSymbolName[2] = (byte)'r';
+                    blobSymbolName[3] = (byte)'a';
+                    blobSymbolName[4] = (byte)'m';
+                    EmitSymbolDef(blobSymbolName);
+                }
             }
 
             // Emit individual cfi blob for the given offset