Auto merge of #25627 - murarth:execution-engine-fix, r=nrc

* Removes `RustJITMemoryManager` from public API.
  This was really sort of an implementation detail to begin with.
* `__morestack` is linked to C++ wrapper code and this pointer
  is used when resolving the symbol for `ExecutionEngine` code.
* `__morestack_addr` is also resolved for `ExecutionEngine` code.
  This function is sometimes referenced in LLVM-generated code,
  but was not able to be resolved on Mac OS systems.
* Added Windows support to `ExecutionEngine` API.
* Added a test for basic `ExecutionEngine` functionality.

src/librustc_llvm/lib.rs

@@ -478,9 +478,6 @@ pub type BuilderRef = *mut Builder_opaque;
 pub enum ExecutionEngine_opaque {}
 pub type ExecutionEngineRef = *mut ExecutionEngine_opaque;
 #[allow(missing_copy_implementations)]
-pub enum RustJITMemoryManager_opaque {}
-pub type RustJITMemoryManagerRef = *mut RustJITMemoryManager_opaque;
-#[allow(missing_copy_implementations)]
 pub enum MemoryBuffer_opaque {}
 pub type MemoryBufferRef = *mut MemoryBuffer_opaque;
 #[allow(missing_copy_implementations)]
@@ -1090,10 +1087,7 @@ extern {
     pub fn LLVMDisposeBuilder(Builder: BuilderRef);
 
     /* Execution engine */
-    pub fn LLVMRustCreateJITMemoryManager(morestack: *const ())
-                                          -> RustJITMemoryManagerRef;
-    pub fn LLVMBuildExecutionEngine(Mod: ModuleRef,
-                                    MM: RustJITMemoryManagerRef) -> ExecutionEngineRef;
+    pub fn LLVMBuildExecutionEngine(Mod: ModuleRef) -> ExecutionEngineRef;
     pub fn LLVMDisposeExecutionEngine(EE: ExecutionEngineRef);
     pub fn LLVMExecutionEngineFinalizeObject(EE: ExecutionEngineRef);
     pub fn LLVMRustLoadDynamicLibrary(path: *const c_char) -> Bool;

src/rustllvm/ExecutionEngineWrapper.cpp

@@ -16,34 +16,38 @@ using namespace llvm;
 using namespace llvm::sys;
 using namespace llvm::object;
 
+// libmorestack is not used on Windows
+#ifndef _WIN32
+extern "C" void __morestack(void);
+
+static void* morestack_addr() {
+    return reinterpret_cast<void*>(__morestack);
+}
+#endif
+
 class RustJITMemoryManager : public SectionMemoryManager
 {
     typedef SectionMemoryManager Base;
 
-    const void *morestack;
-
     public:
 
-    RustJITMemoryManager(const void *morestack_ptr)
-        : morestack(morestack_ptr)
-        {}
+    RustJITMemoryManager() {}
 
     uint64_t getSymbolAddress(const std::string &Name) override
     {
+#ifndef _WIN32
         if (Name == "__morestack" || Name == "___morestack")
-            return reinterpret_cast<uint64_t>(morestack);
+            return reinterpret_cast<uint64_t>(__morestack);
+        if (Name == "__morestack_addr" || Name == "___morestack_addr")
+            return reinterpret_cast<uint64_t>(morestack_addr);
+#endif
 
         return Base::getSymbolAddress(Name);
     }
 };
 
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(RustJITMemoryManager, LLVMRustJITMemoryManagerRef)
 
-extern "C" LLVMRustJITMemoryManagerRef LLVMRustCreateJITMemoryManager(void *morestack)
-{
-    return wrap(new RustJITMemoryManager(morestack));
-}
-
 extern "C" LLVMBool LLVMRustLoadDynamicLibrary(const char *path)
 {
     std::string err;
@@ -60,6 +64,13 @@ extern "C" LLVMBool LLVMRustLoadDynamicLibrary(const char *path)
 extern "C" void LLVMExecutionEngineAddModule(
     LLVMExecutionEngineRef eeref, LLVMModuleRef mref)
 {
+#ifdef _WIN32
+    // On Windows, MCJIT must generate ELF objects
+    std::string target = getProcessTriple();
+    target += "-elf";
+    target = Triple::normalize(target);
+    unwrap(mref)->setTargetTriple(target);
+#endif
     LLVMAddModule(eeref, mref);
 }
 
@@ -74,27 +85,36 @@ extern "C" LLVMBool LLVMExecutionEngineRemoveModule(
     return ee->removeModule(m);
 }
 
-extern "C" LLVMExecutionEngineRef LLVMBuildExecutionEngine(
-    LLVMModuleRef mod, LLVMRustJITMemoryManagerRef mref)
+extern "C" LLVMExecutionEngineRef LLVMBuildExecutionEngine(LLVMModuleRef mod)
 {
     // These are necessary for code generation to work properly.
     InitializeNativeTarget();
     InitializeNativeTargetAsmPrinter();
     InitializeNativeTargetAsmParser();
 
+#ifdef _WIN32
+    // On Windows, MCJIT must generate ELF objects
+    std::string target = getProcessTriple();
+    target += "-elf";
+    target = Triple::normalize(target);
+    unwrap(mod)->setTargetTriple(target);
+#endif
+
     std::string error_str;
     TargetOptions options;
 
     options.JITEmitDebugInfo = true;
     options.NoFramePointerElim = true;
 
+    RustJITMemoryManager *mm = new RustJITMemoryManager;
+
     ExecutionEngine *ee =
     #if LLVM_VERSION_MINOR >= 6
         EngineBuilder(std::unique_ptr<Module>(unwrap(mod)))
-            .setMCJITMemoryManager(std::unique_ptr<RustJITMemoryManager>(unwrap(mref)))
+            .setMCJITMemoryManager(std::unique_ptr<RustJITMemoryManager>(mm))
     #else
         EngineBuilder(unwrap(mod))
-            .setMCJITMemoryManager(unwrap(mref))
+            .setMCJITMemoryManager(mm)
     #endif
             .setEngineKind(EngineKind::JIT)
             .setErrorStr(&error_str)

src/rustllvm/rustllvm.h

@@ -51,14 +51,6 @@
 #include "llvm/IR/DIBuilder.h"
 #include "llvm/Linker/Linker.h"
 
-// Used by RustMCJITMemoryManager::getPointerToNamedFunction()
-// to get around glibc issues. See the function for more information.
-#ifdef __linux__
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#endif
-
 void LLVMRustSetLastError(const char*);
 
 typedef struct OpaqueRustString *RustStringRef;

src/test/run-make/execution-engine/Makefile

@@ -0,0 +1,8 @@
+-include ../tools.mk
+
+# This is a basic test of LLVM ExecutionEngine functionality using compiled
+# Rust code built using the `rustc` crate.
+
+all:
+	$(RUSTC) test.rs
+	$(call RUN,test $(RUSTC))