Implement limiting WebAssembly execution with fuel

Cargo.toml

@@ -55,6 +55,7 @@ test-programs = { path = "crates/test-programs" }
 wasmtime-fuzzing = { path = "crates/fuzzing" }
 wasmtime-runtime = { path = "crates/runtime" }
 tracing-subscriber = "0.2.0"
+wast = "32.0.0"
 
 [build-dependencies]
 anyhow = "1.0.19"

cranelift/src/souper_harvest.rs

@@ -12,7 +12,7 @@ static WASM_MAGIC: &[u8] = &[0x00, 0x61, 0x73, 0x6D];
 /// Harvest candidates for superoptimization from a Wasm or Clif file.
 ///
 /// Candidates are emitted in Souper's text format:
-/// https://github.com/google/souper
+/// <https://github.com/google/souper>
 #[derive(StructOpt)]
 pub struct Options {
     /// Specify an input file to be used. Use '-' for stdin.

cranelift/wasm/src/code_translator.rs

@@ -261,7 +261,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
                 .extend_from_slice(builder.block_params(loop_body));
 
             builder.switch_to_block(loop_body);
-            environ.translate_loop_header(builder.cursor())?;
+            environ.translate_loop_header(builder)?;
         }
         Operator::If { ty } => {
             let val = state.pop1();

cranelift/wasm/src/environ/spec.rs

@@ -295,6 +295,12 @@ pub trait FuncEnvironment: TargetEnvironment {
         ReturnMode::NormalReturns
     }
 
+    /// Called after the locals for a function have been parsed, and the number
+    /// of variables defined by this function is provided.
+    fn after_locals(&mut self, num_locals_defined: usize) {
+        drop(num_locals_defined);
+    }
+
     /// Set up the necessary preamble definitions in `func` to access the global variable
     /// identified by `index`.
     ///
@@ -637,7 +643,7 @@ pub trait FuncEnvironment: TargetEnvironment {
     ///
     /// This can be used to insert explicit interrupt or safepoint checking at
     /// the beginnings of loops.
-    fn translate_loop_header(&mut self, _pos: FuncCursor) -> WasmResult<()> {
+    fn translate_loop_header(&mut self, _builder: &mut FunctionBuilder) -> WasmResult<()> {
         // By default, don't emit anything.
         Ok(())
     }

cranelift/wasm/src/func_translator.rs

@@ -170,6 +170,8 @@ fn parse_local_decls<FE: FuncEnvironment + ?Sized>(
         declare_locals(builder, count, ty, &mut next_local, environ)?;
     }
 
+    environ.after_locals(next_local);
+
     Ok(())
 }
 

crates/cranelift/Cargo.toml

@@ -17,3 +17,4 @@ cranelift-wasm = { path = "../../cranelift/wasm", version = "0.69.0" }
 cranelift-codegen = { path = "../../cranelift/codegen", version = "0.69.0" }
 cranelift-frontend = { path = "../../cranelift/frontend", version = "0.69.0" }
 cranelift-entity = { path = "../../cranelift/entity", version = "0.69.0" }
+wasmparser = "0.73.0"