Use the target-lexicon crate.

This switches from a custom list of architectures to use the
target-lexicon crate.

 - "set is_64bit=1; isa x86" is replaced with "target x86_64", and
   similar for other architectures, and the `is_64bit` flag is removed
   entirely.

 - The `is_compressed` flag is removed too; it's no longer being used to
   control REX prefixes on x86-64, ARM and Thumb are separate
   architectures in target-lexicon, and we can figure out how to
   select RISC-V compressed encodings when we're ready.

lib/wasm/src/environ/dummy.rs

@@ -8,6 +8,7 @@ use environ::{FuncEnvironment, GlobalValue, ModuleEnvironment, WasmResult};
 use func_translator::FuncTranslator;
 use std::string::String;
 use std::vec::Vec;
+use target_lexicon::Triple;
 use translation_utils::{FunctionIndex, Global, GlobalIndex, Memory, MemoryIndex, SignatureIndex,
                         Table, TableIndex};
 use wasmparser;
@@ -39,6 +40,9 @@ impl<T> Exportable<T> {
 /// `DummyEnvironment` to allow it to be borrowed separately from the
 /// `FuncTranslator` field.
 pub struct DummyModuleInfo {
+    /// Target description.
+    pub triple: Triple,
+
     /// Compilation setting flags.
     pub flags: settings::Flags,
 
@@ -69,8 +73,9 @@ pub struct DummyModuleInfo {
 
 impl DummyModuleInfo {
     /// Allocates the data structures with the given flags.
-    pub fn with_flags(flags: settings::Flags) -> Self {
+    pub fn with_triple_flags(triple: Triple, flags: settings::Flags) -> Self {
         Self {
+            triple,
             flags,
             signatures: Vec::new(),
             imported_funcs: Vec::new(),
@@ -100,14 +105,14 @@ pub struct DummyEnvironment {
 
 impl DummyEnvironment {
     /// Allocates the data structures with default flags.
-    pub fn default() -> Self {
-        Self::with_flags(settings::Flags::new(settings::builder()))
+    pub fn with_triple(triple: Triple) -> Self {
+        Self::with_triple_flags(triple, settings::Flags::new(settings::builder()))
     }
 
     /// Allocates the data structures with the given flags.
-    pub fn with_flags(flags: settings::Flags) -> Self {
+    pub fn with_triple_flags(triple: Triple, flags: settings::Flags) -> Self {
         Self {
-            info: DummyModuleInfo::with_flags(flags),
+            info: DummyModuleInfo::with_triple_flags(triple, flags),
             trans: FuncTranslator::new(),
             func_bytecode_sizes: Vec::new(),
         }
@@ -143,6 +148,10 @@ impl<'dummy_environment> DummyFuncEnvironment<'dummy_environment> {
 }
 
 impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environment> {
+    fn triple(&self) -> &Triple {
+        &self.mod_info.triple
+    }
+
     fn flags(&self) -> &settings::Flags {
         &self.mod_info.flags
     }

lib/wasm/src/environ/spec.rs

@@ -4,6 +4,7 @@ use cretonne_codegen::cursor::FuncCursor;
 use cretonne_codegen::ir::{self, InstBuilder};
 use cretonne_codegen::settings::Flags;
 use std::vec::Vec;
+use target_lexicon::Triple;
 use translation_utils::{FunctionIndex, Global, GlobalIndex, Memory, MemoryIndex, SignatureIndex,
                         Table, TableIndex};
 use wasmparser::BinaryReaderError;
@@ -74,6 +75,9 @@ pub type WasmResult<T> = Result<T, WasmError>;
 /// IR. The function environment provides information about the WebAssembly module as well as the
 /// runtime environment.
 pub trait FuncEnvironment {
+    /// Get the triple for the current compilation.
+    fn triple(&self) -> &Triple;
+
     /// Get the flags for the current compilation.
     fn flags(&self) -> &Flags;
 
@@ -81,11 +85,7 @@ pub trait FuncEnvironment {
     ///
     /// This returns `I64` for 64-bit architectures and `I32` for 32-bit architectures.
     fn native_pointer(&self) -> ir::Type {
-        if self.flags().is_64bit() {
-            ir::types::I64
-        } else {
-            ir::types::I32
-        }
+        ir::Type::int(u16::from(self.triple().pointer_width().unwrap().bits())).unwrap()
     }
 
     /// Set up the necessary preamble definitions in `func` to access the global variable

lib/wasm/src/func_translator.rs

@@ -237,6 +237,7 @@ mod tests {
     use cretonne_codegen::ir::types::I32;
     use cretonne_codegen::{ir, Context};
     use environ::{DummyEnvironment, FuncEnvironment};
+    use target_lexicon::Triple;
 
     #[test]
     fn small1() {
@@ -256,7 +257,7 @@ mod tests {
         ];
 
         let mut trans = FuncTranslator::new();
-        let runtime = DummyEnvironment::default();
+        let runtime = DummyEnvironment::with_triple(Triple::default());
         let mut ctx = Context::new();
 
         ctx.func.name = ir::ExternalName::testcase("small1");
@@ -289,7 +290,7 @@ mod tests {
         ];
 
         let mut trans = FuncTranslator::new();
-        let runtime = DummyEnvironment::default();
+        let runtime = DummyEnvironment::with_triple(Triple::default());
         let mut ctx = Context::new();
 
         ctx.func.name = ir::ExternalName::testcase("small2");
@@ -335,7 +336,7 @@ mod tests {
         ];
 
         let mut trans = FuncTranslator::new();
-        let runtime = DummyEnvironment::default();
+        let runtime = DummyEnvironment::with_triple(Triple::default());
         let mut ctx = Context::new();
 
         ctx.func.name = ir::ExternalName::testcase("infloop");

lib/wasm/src/lib.rs

@@ -34,6 +34,7 @@ extern crate hashmap_core;
 #[macro_use(dbg)]
 extern crate cretonne_codegen;
 extern crate cretonne_frontend;
+extern crate target_lexicon;
 extern crate wasmparser;
 
 extern crate failure;