Make more code work with no_std. (#407)

* Make more code work with no_std.

no_std support is still incomplete, but this patch takes care of the
bulk of the straightforward parts.

wasmtime-jit/src/action.rs

@@ -2,11 +2,11 @@
 
 use crate::compiler::Compiler;
 use crate::instantiate::SetupError;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::cmp::max;
 use core::{fmt, mem, ptr, slice};
 use cranelift_codegen::ir;
-use std::string::String;
-use std::vec::Vec;
 use wasmtime_runtime::{wasmtime_call_trampoline, Export, InstanceHandle, VMInvokeArgument};
 
 /// A runtime value.

wasmtime-jit/src/code_memory.rs

@@ -1,10 +1,10 @@
 //! Memory management for executable code.
 
+use alloc::boxed::Box;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::{cmp, mem};
 use region;
-use std::boxed::Box;
-use std::string::String;
-use std::vec::Vec;
 use wasmtime_runtime::{Mmap, VMFunctionBody};
 
 /// Memory manager for executable code.

wasmtime-jit/src/compiler.rs

@@ -4,6 +4,9 @@ use super::HashMap;
 use crate::code_memory::CodeMemory;
 use crate::instantiate::SetupError;
 use crate::target_tunables::target_tunables;
+use alloc::boxed::Box;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::convert::TryFrom;
 use cranelift_codegen::ir::InstBuilder;
 use cranelift_codegen::isa::{TargetFrontendConfig, TargetIsa};
@@ -12,9 +15,6 @@ use cranelift_codegen::{binemit, ir};
 use cranelift_entity::{EntityRef, PrimaryMap};
 use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
 use cranelift_wasm::{DefinedFuncIndex, DefinedMemoryIndex};
-use std::boxed::Box;
-use std::string::String;
-use std::vec::Vec;
 use wasmtime_debug::{emit_debugsections_image, DebugInfoData};
 use wasmtime_environ::{
     Compilation, CompileError, Compiler as _C, FunctionBodyData, Module, ModuleVmctxInfo,

wasmtime-jit/src/context.rs

@@ -1,15 +1,15 @@
 use crate::action::{get, inspect_memory, invoke};
+use crate::HashMap;
 use crate::{
     instantiate, ActionError, ActionOutcome, CompilationStrategy, Compiler, InstanceHandle,
     Namespace, RuntimeValue, SetupError,
 };
+use alloc::boxed::Box;
+use alloc::rc::Rc;
+use alloc::string::{String, ToString};
+use core::cell::RefCell;
+use core::{fmt, str};
 use cranelift_codegen::isa::TargetIsa;
-use std::boxed::Box;
-use std::cell::RefCell;
-use std::collections::HashMap;
-use std::rc::Rc;
-use std::string::{String, ToString};
-use std::{fmt, str};
 use wasmparser::{validate, OperatorValidatorConfig, ValidatingParserConfig};
 
 /// Indicates an unknown instance was specified.

wasmtime-jit/src/instantiate.rs

@@ -7,14 +7,15 @@ use super::HashMap;
 use crate::compiler::Compiler;
 use crate::link::link_module;
 use crate::resolver::Resolver;
+use alloc::boxed::Box;
+use alloc::rc::Rc;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::cell::RefCell;
 use cranelift_entity::{BoxedSlice, PrimaryMap};
 use cranelift_wasm::{DefinedFuncIndex, SignatureIndex};
-use std::boxed::Box;
+#[cfg(feature = "std")]
 use std::io::Write;
-use std::rc::Rc;
-use std::string::String;
-use std::vec::Vec;
 use wasmtime_debug::read_debuginfo;
 use wasmtime_environ::{
     CompileError, DataInitializer, DataInitializerLocation, Module, ModuleEnvironment,
@@ -117,6 +118,7 @@ impl<'data> RawCompiledModule<'data> {
         // Make all code compiled thus far executable.
         compiler.publish_compiled_code();
 
+        #[cfg(feature = "std")]
         let dbg_jit_registration = if let Some(img) = dbg_image {
             let mut bytes = Vec::new();
             bytes.write_all(&img).expect("all written");

wasmtime-jit/src/lib.rs

@@ -21,19 +21,14 @@
         clippy::use_self
     )
 )]
-#![no_std]
+
+#[macro_use]
+extern crate alloc;
 
 #[cfg(not(feature = "std"))]
-#[macro_use]
-extern crate alloc as std;
+use hashbrown::{hash_map, HashMap, HashSet};
 #[cfg(feature = "std")]
-#[macro_use]
-extern crate std;
-
-#[cfg(not(feature = "std"))]
-use hashbrown::{hash_map, HashMap};
-#[cfg(feature = "std")]
-use std::collections::{hash_map, HashMap};
+use std::collections::{hash_map, HashMap, HashSet};
 
 #[macro_use]
 extern crate failure_derive;

wasmtime-jit/src/link.rs

@@ -1,13 +1,13 @@
 //! Linking for JIT-compiled code.
 
 use crate::resolver::Resolver;
+use crate::HashSet;
+use alloc::vec::Vec;
 use core::ptr::write_unaligned;
 use cranelift_codegen::binemit::Reloc;
 use cranelift_codegen::ir::JumpTableOffsets;
 use cranelift_entity::PrimaryMap;
 use cranelift_wasm::{DefinedFuncIndex, Global, GlobalInit, Memory, Table, TableElementType};
-use std::collections::HashSet;
-use std::vec::Vec;
 use wasmtime_environ::{
     MemoryPlan, MemoryStyle, Module, Relocation, RelocationTarget, Relocations, TablePlan,
 };

wasmtime-jit/src/namespace.rs

@@ -4,7 +4,7 @@
 
 use super::HashMap;
 use crate::resolver::Resolver;
-use std::string::String;
+use alloc::string::String;
 use wasmtime_runtime::{Export, InstanceHandle};
 
 /// A namespace containing instances keyed by name.