Add basic metrics collection

CMakeLists.txt

@@ -7,6 +7,10 @@ if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
                PROPERTY VALUE "${CMAKE_BINARY_DIR}/install")
 endif()
 
+# Add rpath to link with dependencies shared libraries
+set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)
+set(CMAKE_INSTALL_RPATH "\${ORIGIN}/../lib")
+
 option(PROT_ENABLE_WERROR "Enable -Werror option (CI)" OFF)
 option(PROT_BUILD_BENCHMARKS
        "Enable benchmarks build (requires riscv gnu toolchain)" OFF)

cmake/dependencies.cmake

@@ -64,3 +64,16 @@ CPMAddPackage(
   OPTIONS "BUILD_TESTING OFF"
   DOWNLOAD_ONLY True
 )
+
+# perf-cpp
+CPMAddPackage(
+  NAME perf-cpp
+  GITHUB_REPOSITORY jmuehlig/perf-cpp
+  GIT_TAG v0.12.6
+  # Don't add EXCLUDE_FROM_ALL, as perf-cpp will be used as shared library
+  SYSTEM True
+  OPTIONS
+  "BUILD_LIB_SHARED ON"
+  "CMAKE_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_PREFIX}/lib"
+)
+target_include_directories(perf-cpp PUBLIC $<BUILD_INTERFACE:${perf-cpp_SOURCE_DIR}/include>)

src/jit/base/base.cc

@@ -38,7 +38,7 @@ void JitEngine::step(CPUState &cpu) {
         }
         curAddr += isa::kWordSize;
       }
-    } else if (bbIt->second.num_exec >= kExecThreshold) [[likely]] {
+    } else if (bbIt->second.num_exec >= m_translationThreshold) [[likely]] {
       auto code = translate(bbIt->second);
       m_tbCache.insert(pc, code);
       if (code != nullptr) [[likely]] {
@@ -60,7 +60,7 @@ void JitEngine::interpret(CPUState &cpu, BBInfo &info) {
 
 auto JitEngine::getBBInfo(isa::Addr pc) const -> const BBInfo * {
   if (const auto found = m_cacheBB.find(pc); found != m_cacheBB.end()) {
-    if (found->second.num_exec >= kExecThreshold) {
+    if (found->second.num_exec >= m_translationThreshold) {
       return &found->second;
     }
   }

src/jit/base/include/prot/jit/base.hh

@@ -3,6 +3,7 @@
 
 #include "prot/interpreter.hh"
 
+#include <cstddef>
 #include <functional>
 #include <map>
 #include <unordered_map>
@@ -11,10 +12,11 @@
 namespace prot::engine {
 using JitFunction = void (*)(CPUState &);
 class JitEngine : public Interpreter {
-  static constexpr std::size_t kExecThreshold = 10;
-
 public:
   void step(CPUState &cpu) override;
+  void setTranslationThreshold(size_t threshold) {
+    m_translationThreshold = threshold;
+  }
 
 protected:
   struct TbCache {
@@ -63,6 +65,7 @@ private:
 private:
   [[nodiscard]] virtual JitFunction translate(const BBInfo &info) = 0;
 
+  size_t m_translationThreshold = 0;
   TbCache m_tbCache;
   std::unordered_map<isa::Addr, BBInfo> m_cacheBB;
 };

tools/bench/CLAUDE_Plot.md

@@ -0,0 +1,114 @@
+# CLAUDE_Plot.md — Benchmark Metrics Plotter
+
+## Project overview
+
+`Plot.py` — a single Python script for visu alising benchmark performance
+data collected across multiple series (e.g. JIT compilers, build configs).
+Produces SVG charts. Two regimes selectable via `--regime`.
+
+## Usage
+
+```bash
+# Bars: compare absolute metric values across series
+python3 Plot.py \
+    --regime bars \
+    --data results/llvm results/asmjit results/gcc \
+    --metrics cycles ipc l1i-cache-misses \
+    --out plots/
+
+# Graphs: show how metrics scale with a base metric (workload scaling)
+python3 Plot.py \
+    --regime graphs \
+    --data results/llvm results/asmjit results/gcc \
+    --base-metric instructions \
+    --metrics cycles ipc \
+    --out plots/
+```
+
+## CLI arguments
+
+| Argument | Required | Description |
+|---|---|---|
+| `--regime` | yes | `bars` or `graphs` |
+| `--data` | yes | One or more series directories; dir name = legend label |
+| `--metrics` | yes | CSV column names to plot |
+| `--base-metric` | graphs only | Column used as X axis (workload proxy) |
+| `--out` | no | Output directory for SVGs (default: `./plots`) |
+| `--logx` | no | Logarithmic X axis (graphs regime only) |
+| `--logy` | no | Logarithmic Y axis (both regimes) |
+
+## Data layouts
+
+### `bars` regime
+
+```
+<series-dir>/
+    <benchmark>.csv     ← rows = independent repeated runs
+```
+
+- Benchmarks matched across series by filename (without extension)
+- One SVG per metric, named `<metric>.svg`
+
+### `graphs` regime
+
+```
+<series-dir>/
+    <benchmark>/
+        <workload_size>.csv   ← rows = independent repeated runs at that size
+```
+
+- Benchmarks matched across series by sub-directory name
+- One SVG per dependent metric, named `<metric>_vs_<base-metric>.svg`
+
+## CSV format
+
+Plain CSV with a header row. Column names are metric names. Each data row is
+one independent run. Example:
+
+```
+instructions,cycles,branches,l1i-cache-misses
+100,50,10,1
+110,50,11,2
+```
+
+## How values are computed
+
+- **Bar height / line Y point** — geometric mean of all rows in a CSV file
+- **Error bars / shaded band** — ±1 standard deviation across rows
+- **Line X point** (`graphs` only) — geometric mean of `--base-metric` in that CSV
+
+Geomean is used rather than arithmetic mean because it is more appropriate for
+ratios and hardware counters that span orders of magnitude. Non-positive and
+non-finite values are excluded before computing geomean (required since
+`log(x)` is undefined for `x ≤ 0`).
+
+## Axis formatting
+
+On linear axes, matplotlib's `ScalarFormatter` is used with `useMathText=True`
+and `powerlimits=(-3, 3)`, which produces an automatic `×10^N` offset label
+when values are large or small. The axis label shows only the bare metric name.
+
+On log axes (`--logx` / `--logy`), matplotlib's default `LogFormatter` is used,
+showing ticks in `10^x` notation. `nonpositive="clip"` is passed to
+`set_xscale`/`set_yscale` so that bars starting from 0 and any negative
+error-bar lower bounds are silently clipped to a small positive value rather
+than crashing or producing invisible elements.
+
+## Dependencies
+
+```bash
+pip install numpy pandas matplotlib
+```
+
+## Known issues / notes
+
+- In `graphs_plot`, the emptiness check on `all_benches` is now an `assert`
+  rather than a soft print-and-return, reflecting that an empty `series_data`
+  should be caught upstream in `run_graphs` and never reach this point.
+- `--base-metric` is silently ignored when `--regime bars` is used.
+- Series with no valid CSV files produce a warning and are skipped rather than
+  causing a hard error.
+- In `graphs` regime, CSV files missing the dependent metric column produce a
+  warning and are skipped (the base metric missing is also warned).
+- Missing benchmark/series combinations in `bars` regime show an "N/A"
+  annotation on the bar rather than crashing.