Add support for generating perf maps for simple perf profiling (#6030)

* Add support for generating perf maps for simple perf profiling

* add missing enum entry in C code

* bugfix: use hexa when printing the code region's length too (thanks bjorn3!)

* sanitize file name + use bufwriter

* introduce --profile CLI flag for wasmtime

* Update doc and doc comments for new --profile option

* remove redundant FromStr import

* Apply review feedback: make_line receives a Write impl, report errors

* fix tests?

* better docs

crates/wasmtime/src/config.rs

@@ -6,13 +6,14 @@ use std::collections::{HashMap, HashSet};
 use std::fmt;
 #[cfg(feature = "cache")]
 use std::path::Path;
+use std::str::FromStr;
 use std::sync::Arc;
 use target_lexicon::Architecture;
 use wasmparser::WasmFeatures;
 #[cfg(feature = "cache")]
 use wasmtime_cache::CacheConfig;
 use wasmtime_environ::Tunables;
-use wasmtime_jit::{JitDumpAgent, NullProfilerAgent, ProfilingAgent, VTuneAgent};
+use wasmtime_jit::{JitDumpAgent, NullProfilerAgent, PerfMapAgent, ProfilingAgent, VTuneAgent};
 use wasmtime_runtime::{InstanceAllocator, OnDemandInstanceAllocator, RuntimeMemoryCreator};
 
 pub use wasmtime_environ::CacheStore;
@@ -221,7 +222,6 @@ impl Config {
     #[cfg(compiler)]
     #[cfg_attr(nightlydoc, doc(cfg(feature = "cranelift")))] // see build.rs
     pub fn target(&mut self, target: &str) -> Result<&mut Self> {
-        use std::str::FromStr;
         self.compiler_config.target =
             Some(target_lexicon::Triple::from_str(target).map_err(|e| anyhow::anyhow!(e))?);
 
@@ -1536,6 +1536,7 @@ impl Config {
 
     pub(crate) fn build_profiler(&self) -> Result<Box<dyn ProfilingAgent>> {
         Ok(match self.profiling_strategy {
+            ProfilingStrategy::PerfMap => Box::new(PerfMapAgent::new()?) as Box<dyn ProfilingAgent>,
             ProfilingStrategy::JitDump => Box::new(JitDumpAgent::new()?) as Box<dyn ProfilingAgent>,
             ProfilingStrategy::VTune => Box::new(VTuneAgent::new()?) as Box<dyn ProfilingAgent>,
             ProfilingStrategy::None => Box::new(NullProfilerAgent),
@@ -1727,11 +1728,14 @@ pub enum OptLevel {
 }
 
 /// Select which profiling technique to support.
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub enum ProfilingStrategy {
     /// No profiler support.
     None,
 
+    /// Collect function name information as the "perf map" file format, used with `perf` on Linux.
+    PerfMap,
+
     /// Collect profiling info for "jitdump" file format, used with `perf` on
     /// Linux.
     JitDump,
@@ -1740,6 +1744,20 @@ pub enum ProfilingStrategy {
     VTune,
 }
 
+impl FromStr for ProfilingStrategy {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        match s {
+            "none" => Ok(Self::None),
+            "perfmap" => Ok(Self::PerfMap),
+            "jitdump" => Ok(Self::JitDump),
+            "vtune" => Ok(Self::VTune),
+            _ => anyhow::bail!("unknown value for profiling strategy"),
+        }
+    }
+}
+
 /// Select how wasm backtrace detailed information is handled.
 #[derive(Debug, Clone, Copy)]
 pub enum WasmBacktraceDetails {