Merge #367

367: Add caching support to llvm backend r=lachlansneff a=lachlansneff

This changes the `CacheGen` trait a little, since it was weird.

Co-authored-by: Lachlan Sneff <lachlan.sneff@gmail.com>

Author: bors[bot]

CHANGELOG.md

@@ -5,6 +5,7 @@ All PRs to the Wasmer repository must add to this file.
 Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
+- [#367](https://github.com/wasmerio/wasmer/pull/367) Add caching support to the LLVM backend.
 - [#366](https://github.com/wasmerio/wasmer/pull/366) Remove `UserTrapper` trait to fix [#365](https://github.com/wasmerio/wasmer/issues/365).
 - [#348](https://github.com/wasmerio/wasmer/pull/348) Refactor internal runtime ↔️ backend abstraction.
 - [#355](https://github.com/wasmerio/wasmer/pull/355) Misc changes to `Cargo.toml`s for publishing

lib/clif-backend/src/cache.rs

@@ -27,18 +27,12 @@ impl CacheGenerator {
 }
 
 impl CacheGen for CacheGenerator {
-    fn generate_cache(
-        &self,
-        module: &ModuleInner,
-    ) -> Result<(Box<ModuleInfo>, Box<[u8]>, Memory), Error> {
-        let info = Box::new(module.info.clone());
-
+    fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), Error> {
         // Clone the memory to a new location. This could take a long time,
         // depending on the throughput of your memcpy implementation.
         let compiled_code = (*self.memory).clone();
 
         Ok((
-            info,
             self.backend_cache.into_backend_data()?.into_boxed_slice(),
             compiled_code,
         ))

lib/llvm-backend/cpp/object_loader.cpp

@@ -175,21 +175,26 @@ WasmModule::WasmModule(
         callbacks_t callbacks
 ) : memory_manager(std::unique_ptr<MemoryManager>(new MemoryManager(callbacks)))
 {
-    object_file = llvm::cantFail(llvm::object::ObjectFile::createObjectFile(llvm::MemoryBufferRef(
-        llvm::StringRef((const char *)object_start, object_size), "object"
-    )));
+    
 
-    SymbolLookup symbol_resolver(callbacks);
-    runtime_dyld = std::unique_ptr<llvm::RuntimeDyld>(new llvm::RuntimeDyld(*memory_manager, symbol_resolver));
+    if (auto created_object_file = llvm::object::ObjectFile::createObjectFile(llvm::MemoryBufferRef(
+        llvm::StringRef((const char *)object_start, object_size), "object"
+    ))) {
+        object_file = cantFail(std::move(created_object_file));
+        SymbolLookup symbol_resolver(callbacks);
+        runtime_dyld = std::unique_ptr<llvm::RuntimeDyld>(new llvm::RuntimeDyld(*memory_manager, symbol_resolver));
 
-    runtime_dyld->setProcessAllSections(true);
+        runtime_dyld->setProcessAllSections(true);
 
-    runtime_dyld->loadObject(*object_file);
-    runtime_dyld->finalizeWithMemoryManagerLocking();
+        runtime_dyld->loadObject(*object_file);
+        runtime_dyld->finalizeWithMemoryManagerLocking();
 
-    if (runtime_dyld->hasError()) {
-        std::cout << "RuntimeDyld error: " << (std::string)runtime_dyld->getErrorString() << std::endl;
-        abort();
+        if (runtime_dyld->hasError()) {
+            _init_failed = true;
+            return;
+        }
+    } else {
+        _init_failed = true;
     }
 }
 

lib/llvm-backend/cpp/object_loader.hh

@@ -152,6 +152,7 @@ struct WasmModule
 
     void *get_func(llvm::StringRef name) const;
 
+    bool _init_failed = false;
   private:
     std::unique_ptr<llvm::RuntimeDyld::MemoryManager> memory_manager;
     std::unique_ptr<llvm::object::ObjectFile> object_file;
@@ -164,6 +165,10 @@ extern "C"
     {
         *module_out = new WasmModule(mem_ptr, mem_size, callbacks);
 
+        if ((*module_out)->_init_failed) {
+            return RESULT_OBJECT_LOAD_FAILURE;
+        }
+
         return RESULT_OK;
     }
 

lib/llvm-backend/src/backend.rs

@@ -13,12 +13,17 @@ use std::{
     any::Any,
     ffi::{c_void, CString},
     mem,
+    ops::Deref,
     ptr::{self, NonNull},
     slice, str,
-    sync::Once,
+    sync::{Arc, Once},
 };
 use wasmer_runtime_core::{
-    backend::RunnableModule,
+    backend::{
+        sys::{Memory, Protect},
+        CacheGen, RunnableModule,
+    },
+    cache::Error as CacheError,
     module::ModuleInfo,
     structures::TypedIndex,
     typed_func::{Wasm, WasmTrapInfo},
@@ -203,17 +208,32 @@ fn get_callbacks() -> Callbacks {
     }
 }
 
+pub enum Buffer {
+    LlvmMemory(MemoryBuffer),
+    Memory(Memory),
+}
+
+impl Deref for Buffer {
+    type Target = [u8];
+    fn deref(&self) -> &[u8] {
+        match self {
+            Buffer::LlvmMemory(mem_buffer) => mem_buffer.as_slice(),
+            Buffer::Memory(memory) => unsafe { memory.as_slice() },
+        }
+    }
+}
+
 unsafe impl Send for LLVMBackend {}
 unsafe impl Sync for LLVMBackend {}
 
 pub struct LLVMBackend {
     module: *mut LLVMModule,
     #[allow(dead_code)]
-    memory_buffer: MemoryBuffer,
+    buffer: Arc<Buffer>,
 }
 
 impl LLVMBackend {
-    pub fn new(module: Module, _intrinsics: Intrinsics) -> Self {
+    pub fn new(module: Module, _intrinsics: Intrinsics) -> (Self, LLVMCache) {
         Target::initialize_x86(&InitializationConfig {
             asm_parser: true,
             asm_printer: true,
@@ -262,10 +282,44 @@ impl LLVMBackend {
             panic!("failed to load object")
         }
 
-        Self {
-            module,
-            memory_buffer,
+        let buffer = Arc::new(Buffer::LlvmMemory(memory_buffer));
+
+        (
+            Self {
+                module,
+                buffer: Arc::clone(&buffer),
+            },
+            LLVMCache { buffer },
+        )
+    }
+
+    pub unsafe fn from_buffer(memory: Memory) -> Result<(Self, LLVMCache), String> {
+        let callbacks = get_callbacks();
+        let mut module: *mut LLVMModule = ptr::null_mut();
+
+        let slice = unsafe { memory.as_slice() };
+
+        let res = module_load(slice.as_ptr(), slice.len(), callbacks, &mut module);
+
+        if res != LLVMResult::OK {
+            return Err("failed to load object".to_string());
         }
+
+        static SIGNAL_HANDLER_INSTALLED: Once = Once::new();
+
+        SIGNAL_HANDLER_INSTALLED.call_once(|| unsafe {
+            crate::platform::install_signal_handler();
+        });
+
+        let buffer = Arc::new(Buffer::Memory(memory));
+
+        Ok((
+            Self {
+                module,
+                buffer: Arc::clone(&buffer),
+            },
+            LLVMCache { buffer },
+        ))
     }
 }
 
@@ -322,6 +376,28 @@ impl RunnableModule for LLVMBackend {
     }
 }
 
+unsafe impl Send for LLVMCache {}
+unsafe impl Sync for LLVMCache {}
+
+pub struct LLVMCache {
+    buffer: Arc<Buffer>,
+}
+
+impl CacheGen for LLVMCache {
+    fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), CacheError> {
+        let mut memory = Memory::with_size_protect(self.buffer.len(), Protect::ReadWrite)
+            .map_err(CacheError::SerializeError)?;
+
+        let buffer = self.buffer.deref();
+
+        unsafe {
+            memory.as_slice_mut()[..buffer.len()].copy_from_slice(buffer);
+        }
+
+        Ok(([].as_ref().into(), memory))
+    }
+}
+
 #[cfg(feature = "disasm")]
 unsafe fn disass_ptr(ptr: *const u8, size: usize, inst_count: usize) {
     use capstone::arch::BuildsCapstone;

lib/llvm-backend/src/lib.rs

@@ -38,39 +38,28 @@ impl Compiler for LLVMCompiler {
         let (info, code_reader) = read_info::read_module(wasm, compiler_config).unwrap();
         let (module, intrinsics) = code::parse_function_bodies(&info, code_reader).unwrap();
 
-        let backend = backend::LLVMBackend::new(module, intrinsics);
+        let (backend, cache_gen) = backend::LLVMBackend::new(module, intrinsics);
 
-        // Create placeholder values here.
-        let cache_gen = {
-            use wasmer_runtime_core::backend::{sys::Memory, CacheGen};
-            use wasmer_runtime_core::cache::Error as CacheError;
-            use wasmer_runtime_core::module::ModuleInfo;
-
-            struct Placeholder;
+        Ok(ModuleInner {
+            runnable_module: Box::new(backend),
+            cache_gen: Box::new(cache_gen),
 
-            impl CacheGen for Placeholder {
-                fn generate_cache(
-                    &self,
-                    _module: &ModuleInner,
-                ) -> Result<(Box<ModuleInfo>, Box<[u8]>, Memory), CacheError> {
-                    unimplemented!()
-                }
-            }
+            info,
+        })
+    }
 
-            Box::new(Placeholder)
-        };
+    unsafe fn from_cache(&self, artifact: Artifact, _: Token) -> Result<ModuleInner, CacheError> {
+        let (info, _, memory) = artifact.consume();
+        let (backend, cache_gen) =
+            backend::LLVMBackend::from_buffer(memory).map_err(CacheError::DeserializeError)?;
 
         Ok(ModuleInner {
             runnable_module: Box::new(backend),
-            cache_gen,
+            cache_gen: Box::new(cache_gen),
 
             info,
         })
     }
-
-    unsafe fn from_cache(&self, _artifact: Artifact, _: Token) -> Result<ModuleInner, CacheError> {
-        unimplemented!("the llvm backend doesn't support caching yet")
-    }
 }
 
 fn validate(bytes: &[u8]) -> Result<(), CompileError> {
@@ -123,7 +112,7 @@ fn test_read_module() {
 
     let (module, intrinsics) = code::parse_function_bodies(&info, code_reader).unwrap();
 
-    let backend = backend::LLVMBackend::new(module, intrinsics);
+    let (backend, _) = backend::LLVMBackend::new(module, intrinsics);
 
     let func_ptr = backend.get_func(&info, LocalFuncIndex::new(0)).unwrap();
 

lib/runtime-core/src/backend.rs

@@ -83,8 +83,5 @@ pub trait RunnableModule: Send + Sync {
 }
 
 pub trait CacheGen: Send + Sync {
-    fn generate_cache(
-        &self,
-        module: &ModuleInner,
-    ) -> Result<(Box<ModuleInfo>, Box<[u8]>, Memory), CacheError>;
+    fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), CacheError>;
 }

lib/runtime-core/src/module.rs

@@ -121,8 +121,12 @@ impl Module {
     }
 
     pub fn cache(&self) -> Result<Artifact, CacheError> {
-        let (info, backend_metadata, code) = self.inner.cache_gen.generate_cache(&self.inner)?;
-        Ok(Artifact::from_parts(info, backend_metadata, code))
+        let (backend_metadata, code) = self.inner.cache_gen.generate_cache()?;
+        Ok(Artifact::from_parts(
+            Box::new(self.inner.info.clone()),
+            backend_metadata,
+            code,
+        ))
     }
 
     pub fn info(&self) -> &ModuleInfo {

lib/runtime-core/src/vm.rs

@@ -569,10 +569,7 @@ mod vm_ctx_tests {
             }
         }
         impl CacheGen for Placeholder {
-            fn generate_cache(
-                &self,
-                module: &ModuleInner,
-            ) -> Result<(Box<ModuleInfo>, Box<[u8]>, Memory), CacheError> {
+            fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), CacheError> {
                 unimplemented!()
             }
         }

lib/runtime/examples/call.rs

@@ -7,8 +7,6 @@ static WAT: &'static str = r#"
       (type (;0;) (func (result i32)))
       (import "env" "do_panic" (func $do_panic (type 0)))
       (func $dbz (result i32)
-        call $do_panic
-        drop
         i32.const 42
         i32.const 0
         i32.div_u

lib/singlepass-backend/src/lib.rs

@@ -36,10 +36,7 @@ use wasmer_runtime_core::{
 
 struct Placeholder;
 impl CacheGen for Placeholder {
-    fn generate_cache(
-        &self,
-        _module: &ModuleInner,
-    ) -> Result<(Box<ModuleInfo>, Box<[u8]>, Memory), CacheError> {
+    fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), CacheError> {
         Err(CacheError::Unknown(
             "the singlepass backend doesn't support caching yet".to_string(),
         ))