Support vtune profiling of trampolines too (#3687)

* Provide helpers for demangling function names

* Profile trampolines in vtune too

* get rid of mapping

* avoid code duplication with jitdump_linux

* maintain previous default display name for wasm functions

* no dash, grrr

* Remove unused profiling error type

crates/jit/src/profiling.rs

@@ -1,6 +1,4 @@
-use crate::CompiledModule;
-use std::error::Error;
-use std::fmt;
+use crate::{demangling::demangle_function_name_or_index, CompiledModule};
 use wasmtime_environ::{DefinedFuncIndex, EntityRef, Module};
 
 cfg_if::cfg_if! {
@@ -30,45 +28,38 @@ pub use vtune::VTuneAgent;
 pub trait ProfilingAgent: Send + Sync + 'static {
     /// Notify the profiler of a new module loaded into memory
     fn module_load(&self, module: &CompiledModule, dbg_image: Option<&[u8]>);
-    /// Notify the profiler that the object file provided contains
-    /// dynamically-generated trampolines which are now being loaded.
-    fn trampoline_load(&self, file: &object::File<'_>);
+
+    /// Notify the profiler about a single dynamically-generated trampoline (for host function)
+    /// that is being loaded now.`
+    fn load_single_trampoline(&self, name: &str, addr: *const u8, size: usize, pid: u32, tid: u32);
 }
 
 /// Default agent for unsupported profiling build.
 #[derive(Debug, Default, Clone, Copy)]
 pub struct NullProfilerAgent;
 
-#[derive(Debug)]
-struct NullProfilerAgentError;
-
-impl fmt::Display for NullProfilerAgentError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "A profiler agent is not supported by this build")
-    }
-}
-
-// This is important for other errors to wrap this one.
-impl Error for NullProfilerAgentError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        // Generic error, underlying cause isn't tracked.
-        None
-    }
-}
-
 impl ProfilingAgent for NullProfilerAgent {
     fn module_load(&self, _module: &CompiledModule, _dbg_image: Option<&[u8]>) {}
-    fn trampoline_load(&self, _file: &object::File<'_>) {}
+    fn load_single_trampoline(
+        &self,
+        _name: &str,
+        _addr: *const u8,
+        _size: usize,
+        _pid: u32,
+        _tid: u32,
+    ) {
+    }
 }
 
 #[allow(dead_code)]
 fn debug_name(module: &Module, index: DefinedFuncIndex) -> String {
     let index = module.func_index(index);
-    match module.func_names.get(&index) {
-        Some(s) => rustc_demangle::try_demangle(s)
-            .map(|demangle| demangle.to_string())
-            .or_else(|_| cpp_demangle::Symbol::new(s).map(|sym| sym.to_string()))
-            .unwrap_or_else(|_| s.clone()),
-        None => format!("wasm::wasm-function[{}]", index.index()),
-    }
+    let mut debug_name = String::new();
+    demangle_function_name_or_index(
+        &mut debug_name,
+        module.func_names.get(&index).map(|s| s.as_str()),
+        index.index(),
+    )
+    .unwrap();
+    debug_name
 }