Merge #1040

1040: Add the ability to pass backend specific options through CompilerConfig. r=nlewycky a=nlewycky

# Description
Add the ability to pass backend specific options through CompilerConfig.

Use this to replace wasmer_llvm_backend::GLOBAL_OPTIONS.

This adds a new item to CompilerConfig which can be any struct defined by a backend for backend specific configuration options. So far, we only implement the options that were previously in GLOBAL_OPTIONS, these move to wasmer.rs. The plan is to use these same callbacks for testing in llvm-backend-tests.

# Review

- [ ] Add a short description of the the change to the CHANGELOG.md file


Co-authored-by: Nick Lewycky <nick@wasmer.io>

lib/llvm-backend/src/backend.rs

@@ -2,6 +2,7 @@ use super::stackmap::StackmapRegistry;
 use crate::{
     intrinsics::Intrinsics,
     structs::{Callbacks, LLVMModule, LLVMResult, MemProtect},
+    LLVMCallbacks,
 };
 use inkwell::{
     memory_buffer::MemoryBuffer,
@@ -13,8 +14,6 @@ use std::{
     any::Any,
     cell::RefCell,
     ffi::{c_void, CString},
-    fs::File,
-    io::Write,
     mem,
     ops::Deref,
     ptr::{self, NonNull},
@@ -176,23 +175,22 @@ impl LLVMBackend {
         _stackmaps: &StackmapRegistry,
         _module_info: &ModuleInfo,
         target_machine: &TargetMachine,
+        llvm_callbacks: &Option<Rc<RefCell<dyn LLVMCallbacks>>>,
     ) -> (Self, LLVMCache) {
         let memory_buffer = target_machine
             .write_to_memory_buffer(&module.borrow_mut(), FileType::Object)
             .unwrap();
-        let mem_buf_slice = memory_buffer.as_slice();
 
-        if let Some(path) = unsafe { &crate::GLOBAL_OPTIONS.obj_file } {
-            let mut file = File::create(path).unwrap();
-            let mut pos = 0;
-            while pos < mem_buf_slice.len() {
-                pos += file.write(&mem_buf_slice[pos..]).unwrap();
-            }
+        if let Some(callbacks) = llvm_callbacks {
+            callbacks
+                .borrow_mut()
+                .obj_memory_buffer_callback(&memory_buffer);
         }
 
         let callbacks = get_callbacks();
         let mut module: *mut LLVMModule = ptr::null_mut();
 
+        let mem_buf_slice = memory_buffer.as_slice();
         let res = unsafe {
             module_load(
                 mem_buf_slice.as_ptr(),

lib/llvm-backend/src/code.rs

@@ -5,6 +5,7 @@ use crate::{
     stackmap::{StackmapEntry, StackmapEntryKind, StackmapRegistry, ValueSemantic},
     state::{ControlFrame, ExtraInfo, IfElseState, State},
     trampolines::generate_trampolines,
+    LLVMBackendConfig, LLVMCallbacks,
 };
 use inkwell::{
     builder::Builder,
@@ -877,6 +878,7 @@ pub struct LLVMModuleCodeGenerator<'ctx> {
     stackmaps: Rc<RefCell<StackmapRegistry>>,
     track_state: bool,
     target_machine: TargetMachine,
+    llvm_callbacks: Option<Rc<RefCell<dyn LLVMCallbacks>>>,
 }
 
 pub struct LLVMFunctionCodeGenerator<'ctx> {
@@ -8513,6 +8515,7 @@ impl<'ctx> ModuleCodeGenerator<LLVMFunctionCodeGenerator<'ctx>, LLVMBackend, Cod
             stackmaps: Rc::new(RefCell::new(StackmapRegistry::default())),
             track_state: false,
             target_machine,
+            llvm_callbacks: None,
         }
     }
 
@@ -8654,8 +8657,10 @@ impl<'ctx> ModuleCodeGenerator<LLVMFunctionCodeGenerator<'ctx>, LLVMBackend, Cod
             message: format!("trampolines generation error: {:?}", e),
         })?;
 
-        if let Some(path) = unsafe { &crate::GLOBAL_OPTIONS.pre_opt_ir } {
-            self.module.borrow_mut().print_to_file(path).unwrap();
+        if let Some(ref mut callbacks) = self.llvm_callbacks {
+            callbacks
+                .borrow_mut()
+                .preopt_ir_callback(&*self.module.borrow_mut());
         }
 
         let pass_manager = PassManager::create(());
@@ -8695,8 +8700,10 @@ impl<'ctx> ModuleCodeGenerator<LLVMFunctionCodeGenerator<'ctx>, LLVMBackend, Cod
         pass_manager.add_early_cse_pass();
 
         pass_manager.run_on(&*self.module.borrow_mut());
-        if let Some(path) = unsafe { &crate::GLOBAL_OPTIONS.post_opt_ir } {
-            self.module.borrow_mut().print_to_file(path).unwrap();
+        if let Some(ref mut callbacks) = self.llvm_callbacks {
+            callbacks
+                .borrow_mut()
+                .postopt_ir_callback(&*self.module.borrow_mut());
         }
 
         let stackmaps = self.stackmaps.borrow();
@@ -8707,12 +8714,18 @@ impl<'ctx> ModuleCodeGenerator<LLVMFunctionCodeGenerator<'ctx>, LLVMBackend, Cod
             &*stackmaps,
             module_info,
             &self.target_machine,
+            &mut self.llvm_callbacks,
         );
         Ok((backend, Box::new(cache_gen)))
     }
 
     fn feed_compiler_config(&mut self, config: &CompilerConfig) -> Result<(), CodegenError> {
         self.track_state = config.track_state;
+        if let Some(backend_compiler_config) = &config.backend_specific_config {
+            if let Some(llvm_config) = backend_compiler_config.get_specific::<LLVMBackendConfig>() {
+                self.llvm_callbacks = llvm_config.callbacks.clone();
+            }
+        }
         Ok(())
     }
 

lib/llvm-backend/src/lib.rs

@@ -21,8 +21,6 @@ mod state;
 mod structs;
 mod trampolines;
 
-use std::path::PathBuf;
-
 pub use code::LLVMFunctionCodeGenerator as FunctionCodeGenerator;
 pub use code::LLVMModuleCodeGenerator as ModuleCodeGenerator;
 
@@ -35,21 +33,15 @@ pub type LLVMCompiler = SimpleStreamingCompilerGen<
     code::CodegenError,
 >;
 
-#[derive(Debug, Clone)]
-/// LLVM backend flags.
-pub struct LLVMOptions {
-    /// Emit LLVM IR before optimization pipeline.
-    pub pre_opt_ir: Option<PathBuf>,
-
-    /// Emit LLVM IR after optimization pipeline.
-    pub post_opt_ir: Option<PathBuf>,
+pub type InkwellModule<'ctx> = inkwell::module::Module<'ctx>;
+pub type InkwellMemoryBuffer = inkwell::memory_buffer::MemoryBuffer;
 
-    /// Emit LLVM generated native code object file.
-    pub obj_file: Option<PathBuf>,
+pub trait LLVMCallbacks: std::any::Any + 'static {
+    fn preopt_ir_callback(&mut self, module: &InkwellModule);
+    fn postopt_ir_callback(&mut self, module: &InkwellModule);
+    fn obj_memory_buffer_callback(&mut self, memory_buffer: &InkwellMemoryBuffer);
 }
 
-pub static mut GLOBAL_OPTIONS: LLVMOptions = LLVMOptions {
-    pre_opt_ir: None,
-    post_opt_ir: None,
-    obj_file: None,
-};
+pub struct LLVMBackendConfig {
+    pub callbacks: Option<std::rc::Rc<std::cell::RefCell<dyn LLVMCallbacks>>>,
+}

lib/runtime-core/src/backend.rs

@@ -200,6 +200,19 @@ pub struct Features {
     pub threads: bool,
 }
 
+/// Use this to point to a compiler config struct provided by the backend.
+/// The backend struct must support runtime reflection with `Any`, which is any
+/// struct that does not contain a non-`'static` reference.
+#[derive(Debug)]
+pub struct BackendCompilerConfig(pub Box<dyn Any + 'static>);
+
+impl BackendCompilerConfig {
+    /// Obtain the backend-specific compiler config struct.
+    pub fn get_specific<T: 'static>(&self) -> Option<&T> {
+        self.0.downcast_ref::<T>()
+    }
+}
+
 /// Configuration data for the compiler
 #[derive(Debug, Default)]
 pub struct CompilerConfig {
@@ -210,10 +223,12 @@ pub struct CompilerConfig {
     pub track_state: bool,
     pub features: Features,
 
-    // target info used by LLVM
+    // Target info. Presently only supported by LLVM.
     pub triple: Option<String>,
     pub cpu_name: Option<String>,
     pub cpu_features: Option<String>,
+
+    pub backend_specific_config: Option<BackendCompilerConfig>,
 }
 
 pub trait Compiler {

src/bin/wasmer.rs

@@ -9,6 +9,7 @@
 )]
 extern crate structopt;
 
+use std::collections::HashMap;
 use std::env;
 use std::fs::{metadata, read_to_string, File};
 use std::io;
@@ -17,14 +18,15 @@ use std::path::PathBuf;
 use std::process::exit;
 use std::str::FromStr;
 
-use std::collections::HashMap;
 use structopt::{clap, StructOpt};
 
 use wasmer::*;
 #[cfg(feature = "backend-cranelift")]
 use wasmer_clif_backend::CraneliftCompiler;
 #[cfg(feature = "backend-llvm")]
-use wasmer_llvm_backend::{LLVMCompiler, LLVMOptions};
+use wasmer_llvm_backend::{
+    InkwellMemoryBuffer, InkwellModule, LLVMBackendConfig, LLVMCallbacks, LLVMCompiler,
+};
 use wasmer_runtime::{
     cache::{Cache as BaseCache, FileSystemCache, WasmHash},
     Value, VERSION,
@@ -40,6 +42,11 @@ use wasmer_runtime_core::{
 #[cfg(feature = "wasi")]
 use wasmer_wasi;
 
+#[cfg(feature = "backend-llvm")]
+use std::{cell::RefCell, io::Write, rc::Rc};
+#[cfg(feature = "backend-llvm")]
+use wasmer_runtime_core::backend::BackendCompilerConfig;
+
 #[derive(Debug, StructOpt)]
 #[structopt(name = "wasmer", about = "Wasm execution runtime.", author)]
 /// The options for the wasmer Command Line Interface
@@ -486,6 +493,32 @@ fn execute_wasi(
     Ok(())
 }
 
+#[cfg(feature = "backend-llvm")]
+impl LLVMCallbacks for LLVMCLIOptions {
+    fn preopt_ir_callback(&mut self, module: &InkwellModule) {
+        if let Some(filename) = &self.pre_opt_ir {
+            module.print_to_file(filename).unwrap();
+        }
+    }
+
+    fn postopt_ir_callback(&mut self, module: &InkwellModule) {
+        if let Some(filename) = &self.post_opt_ir {
+            module.print_to_file(filename).unwrap();
+        }
+    }
+
+    fn obj_memory_buffer_callback(&mut self, memory_buffer: &InkwellMemoryBuffer) {
+        if let Some(filename) = &self.obj_file {
+            let mem_buf_slice = memory_buffer.as_slice();
+            let mut file = File::create(filename).unwrap();
+            let mut pos = 0;
+            while pos < mem_buf_slice.len() {
+                pos += file.write(&mem_buf_slice[pos..]).unwrap();
+            }
+        }
+    }
+}
+
 /// Execute a wasm/wat file
 fn execute_wasm(options: &Run) -> Result<(), String> {
     let disable_cache = options.disable_cache;
@@ -558,22 +591,17 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
             .map_err(|e| format!("Can't convert from wast to wasm: {:?}", e))?;
     }
 
-    let compiler: Box<dyn Compiler> = match get_compiler_by_backend(options.backend, options) {
-        Some(x) => x,
-        None => return Err("the requested backend is not enabled".into()),
-    };
+    let compiler: Box<dyn Compiler> = get_compiler_by_backend(options.backend, options)
+        .ok_or_else(|| "the requested backend is not enabled")?;
 
+    #[allow(unused_mut)]
+    let mut backend_specific_config = None;
     #[cfg(feature = "backend-llvm")]
     {
         if options.backend == Backend::LLVM {
-            let options = options.backend_llvm_options.clone();
-            unsafe {
-                wasmer_llvm_backend::GLOBAL_OPTIONS = LLVMOptions {
-                    pre_opt_ir: options.pre_opt_ir,
-                    post_opt_ir: options.post_opt_ir,
-                    obj_file: options.obj_file,
-                }
-            }
+            backend_specific_config = Some(BackendCompilerConfig(Box::new(LLVMBackendConfig {
+                callbacks: Some(Rc::new(RefCell::new(options.backend_llvm_options.clone()))),
+            })))
         }
     }
 
@@ -598,6 +626,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
                 enforce_stack_check: true,
                 track_state,
                 features: options.features.into_backend_features(),
+                backend_specific_config,
                 ..Default::default()
             },
             &*compiler,
@@ -610,6 +639,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
                 symbol_map: em_symbol_map.clone(),
                 track_state,
                 features: options.features.into_backend_features(),
+                backend_specific_config,
                 ..Default::default()
             },
             &*compiler,
@@ -625,7 +655,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
         let mut cache = unsafe {
             FileSystemCache::new(wasmer_cache_dir).map_err(|e| format!("Cache error: {:?}", e))?
         };
-        let mut load_cache_key = || -> Result<_, String> {
+        let load_cache_key = || -> Result<_, String> {
             if let Some(ref prehashed_cache_key) = options.cache_key {
                 if let Ok(module) =
                     WasmHash::decode(prehashed_cache_key).and_then(|prehashed_key| {
@@ -655,6 +685,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
                             symbol_map: em_symbol_map.clone(),
                             track_state,
                             features: options.features.into_backend_features(),
+                            backend_specific_config,
                             ..Default::default()
                         },
                         &*compiler,