fix(driver): normalize MinGW JIT archive symbol definitions

Make absolute-zero pure virtual fallbacks local and compute runtime archive
interfaces from normalized objects so ORC definitions match JITLink.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 26 insertions, 1 deletions

diff --git a/tools/driver/EmbeddedRunner.cc b/tools/driver/EmbeddedRunner.cc
index 28fe2db..c8c3fcd 100644
--- a/tools/driver/EmbeddedRunner.cc
+++ b/tools/driver/EmbeddedRunner.cc
@@ -5,6 +5,7 @@
 #include "llvm/ExecutionEngine/Orc/AbsoluteSymbols.h"
 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/ExecutionEngine/Orc/ObjectFileInterface.h"
 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/Orc/ThreadSafeModule.h"
 #include "llvm/Support/Error.h"
@@ -439,6 +440,18 @@ static llvm::Error loadCxxRuntime(llvm::orc::LLJIT &J) {
     if (!unpackCxxRuntime(Archives))
         return llvm::make_error<llvm::StringError>("cannot unpack the C++ runtime", llvm::inconvertibleErrorCode());
     for (auto &Archive : Archives) {
+        llvm::orc::StaticLibraryDefinitionGenerator::GetObjectFileInterface GetInterface;
+#if defined(_WIN32) && defined(__x86_64__)
+        // Match the normalized object that MinGWObjectLinkingLayer::emit links.
+        GetInterface = [](llvm::orc::ExecutionSession &ES, llvm::MemoryBufferRef Ref)
+            -> llvm::Expected<llvm::orc::MaterializationUnit::Interface> {
+            auto Normalized = normalizeMinGWObject(
+                llvm::MemoryBuffer::getMemBuffer(Ref, false));
+            if (!Normalized)
+                return Normalized.takeError();
+            return llvm::orc::getObjectFileInterface(ES, (*Normalized)->getMemBufferRef());
+        };
+#endif
         auto Generator = llvm::orc::StaticLibraryDefinitionGenerator::Create(
             J.getObjLinkingLayer(), std::move(Archive),
             [](llvm::object::Archive &, llvm::MemoryBufferRef Buffer, size_t) -> llvm::Expected<bool> {
@@ -458,7 +471,7 @@ static llvm::Error loadCxxRuntime(llvm::orc::LLJIT &J) {
                         N.starts_with("_Unwind_") || N == "_ZTIi") return false;
                 }
                 return true;
-            });
+            }, std::move(GetInterface));
         if (!Generator) return Generator.takeError();
         J.getMainJITDylib().addGenerator(std::move(*Generator));
     }
diff --git a/tools/driver/MinGWCOFF.h b/tools/driver/MinGWCOFF.h
index 186d981..555dcc8 100644
--- a/tools/driver/MinGWCOFF.h
+++ b/tools/driver/MinGWCOFF.h
@@ -50,6 +50,7 @@ normalizeMinGWObject(std::unique_ptr<llvm::MemoryBuffer> Buffer) {
     struct Association { size_t Offset; int32_t Parent; };
     SmallVector<Association, 16> Associations;
     SmallVector<size_t, 2> PureVirtualReferences;
+    SmallVector<size_t, 2> PureVirtualFallbacks;
     for (const auto &Symbol : COFF->symbols()) {
         auto Sym = COFF->getCOFFSymbol(Symbol);
         if (auto *Weak = Sym.getWeakExternal()) {
@@ -68,6 +69,13 @@ normalizeMinGWObject(std::unique_ptr<llvm::MemoryBuffer> Buffer) {
                                   ? offsetof(object::coff_symbol32, StorageClass)
                                   : offsetof(object::coff_symbol16, StorageClass);
                     PureVirtualReferences.push_back(Offset);
+                    size_t FallbackOffset =
+                        reinterpret_cast<const char *>(Fallback->getRawPtr()) -
+                        Buffer->getBufferStart();
+                    FallbackOffset += Fallback->isBigObj()
+                                          ? offsetof(object::coff_symbol32, StorageClass)
+                                          : offsetof(object::coff_symbol16, StorageClass);
+                    PureVirtualFallbacks.push_back(FallbackOffset);
                 }
             }
         }
@@ -118,6 +126,10 @@ normalizeMinGWObject(std::unique_ptr<llvm::MemoryBuffer> Buffer) {
     // entry count intact so the remaining symbol indices do not move.
     for (size_t Offset : PureVirtualReferences)
         Copy->getBufferStart()[Offset] = COFF::IMAGE_SYM_CLASS_EXTERNAL;
+    // Only the now-unused weak auxiliary record references the fallback.
+    // Keep it local so archive interfaces do not advertise a global definition.
+    for (size_t Offset : PureVirtualFallbacks)
+        Copy->getBufferStart()[Offset] = COFF::IMAGE_SYM_CLASS_STATIC;
     return std::unique_ptr<MemoryBuffer>(std::move(Copy));
 }