Tidy up trap-handling code.

lib/execute/src/instance_plus.rs

@@ -12,9 +12,10 @@ use std::slice;
 use std::string::String;
 use std::vec::Vec;
 use std::{mem, ptr};
+use target_tunables::target_tunables;
 use trampoline_park::TrampolinePark;
 use wasmtime_environ::{
-    compile_module, Compilation, CompileError, DataInitializer, Module, ModuleEnvironment, Tunables,
+    compile_module, Compilation, CompileError, DataInitializer, Module, ModuleEnvironment,
 };
 use wasmtime_runtime::{
     wasmtime_call_trampoline, Export, Imports, Instance, InstantiationError, VMFunctionBody,
@@ -42,9 +43,7 @@ impl InstancePlus {
         resolver: &mut Resolver,
     ) -> Result<Self, ActionError> {
         let mut module = Module::new();
-
-        // TODO: Allow the tunables to be overridden.
-        let tunables = Tunables::default();
+        let tunables = target_tunables(isa.triple());
 
         let (lazy_function_body_inputs, lazy_data_initializers) = {
             let environ = ModuleEnvironment::new(isa, &mut module, tunables);

lib/execute/src/lib.rs

@@ -37,12 +37,14 @@ extern crate alloc;
 extern crate failure;
 #[macro_use]
 extern crate failure_derive;
+extern crate target_lexicon;
 
 mod action;
 mod instance_plus;
 mod jit_code;
 mod link;
 mod resolver;
+mod target_tunables;
 mod trampoline_park;
 
 pub use action::{ActionError, ActionOutcome, RuntimeValue};
@@ -50,6 +52,7 @@ pub use instance_plus::InstancePlus;
 pub use jit_code::JITCode;
 pub use link::link_module;
 pub use resolver::{NullResolver, Resolver};
+pub use target_tunables::target_tunables;
 
 #[cfg(not(feature = "std"))]
 mod std {

lib/execute/src/link.rs

@@ -320,7 +320,10 @@ fn relocate(
                         FloorF64 => wasmtime_f64_floor as usize,
                         TruncF64 => wasmtime_f64_trunc as usize,
                         NearestF64 => wasmtime_f64_nearest as usize,
+                        #[cfg(not(target_os = "windows"))]
                         Probestack => __rust_probestack as usize,
+                        #[cfg(all(target_os = "windows", target_pointer_width = "64"))]
+                        Probestack => __chkstk as usize,
                         other => panic!("unexpected libcall: {}", other),
                     }
                 }
@@ -357,5 +360,8 @@ fn relocate(
 /// A declaration for the stack probe function in Rust's standard library, for
 /// catching callstack overflow.
 extern "C" {
+    #[cfg(not(target_os = "windows"))]
     pub fn __rust_probestack();
+    #[cfg(all(target_os = "windows", target_pointer_width = "64"))]
+    pub fn __chkstk();
 }

lib/execute/src/target_tunables.rs

@@ -0,0 +1,22 @@
+use std::cmp::min;
+use target_lexicon::{OperatingSystem, Triple};
+use wasmtime_environ::Tunables;
+
+/// Return a `Tunables` instance tuned for the given target platform.
+pub fn target_tunables(triple: &Triple) -> Tunables {
+    let mut result = Tunables::default();
+
+    match triple.operating_system {
+        OperatingSystem::Windows => {
+            // For now, use a smaller footprint on Windows so that we don't
+            // don't outstrip the paging file.
+            // TODO: Make this configurable.
+            result.static_memory_bound = min(result.static_memory_bound, 0x100);
+            result.static_memory_offset_guard_size =
+                min(result.static_memory_offset_guard_size, 0x10000);
+        }
+        _ => {}
+    }
+
+    result
+}