[analyze-memory] Add function call frequency analysis (#14779)

esphome/analyze_memory/__init__.py

@@ -1,6 +1,6 @@
 """Memory usage analyzer for ESPHome compiled binaries."""
 
-from collections import defaultdict
+from collections import Counter, defaultdict
 from dataclasses import dataclass, field
 import logging
 from pathlib import Path
@@ -40,6 +40,15 @@ _READELF_SECTION_PATTERN = re.compile(
     r"\s*\[\s*\d+\]\s+([\.\w]+)\s+\w+\s+[\da-fA-F]+\s+[\da-fA-F]+\s+([\da-fA-F]+)"
 )
 
+# Regex for extracting call targets from objdump disassembly
+# Matches direct call instructions across architectures:
+#   Xtensa: call0/call4/call8/call12/callx0/callx4/callx8/callx12 <addr> <symbol>
+#   ARM:    bl/blx <addr> <symbol>
+# Captures the mangled symbol name inside angle brackets.
+_CALL_TARGET_PATTERN = re.compile(
+    r"\t(?:call(?:0|4|8|12)|callx(?:0|4|8|12)|blx?)\s+[\da-fA-F]+ <([^>]+)>"
+)
+
 # Component category prefixes
 _COMPONENT_PREFIX_ESPHOME = "[esphome]"
 _COMPONENT_PREFIX_EXTERNAL = "[external]"
@@ -197,6 +206,8 @@ class MemoryAnalyzer:
         self._lib_hash_to_name: dict[str, str] = {}
         # Heuristic category to library redirect: "mdns_lib" -> "[lib]mdns"
         self._heuristic_to_lib: dict[str, str] = {}
+        # Function call counts: mangled_name -> call_count
+        self._function_call_counts: Counter[str] = Counter()
 
     def analyze(self) -> dict[str, ComponentMemory]:
         """Analyze the ELF file and return component memory usage."""
@@ -206,6 +217,7 @@ class MemoryAnalyzer:
         self._categorize_symbols()
         self._analyze_cswtch_symbols()
         self._analyze_sdk_libraries()
+        self._analyze_function_calls()
         return dict(self.components)
 
     def _parse_sections(self) -> None:
@@ -384,8 +396,9 @@ class MemoryAnalyzer:
             return
 
         _LOGGER.info("Demangling %d symbols", len(symbols))
-        self._demangle_cache = batch_demangle(symbols, objdump_path=self.objdump_path)
+        demangled = batch_demangle(symbols, objdump_path=self.objdump_path)
-        _LOGGER.info("Successfully demangled %d symbols", len(self._demangle_cache))
+        self._demangle_cache.update(demangled)
+        _LOGGER.info("Successfully demangled %d symbols", len(demangled))
 
     def _demangle_symbol(self, symbol: str) -> str:
         """Get demangled C++ symbol name from cache."""
@@ -1011,6 +1024,43 @@ class MemoryAnalyzer:
             total_size,
         )
 
+    def _analyze_function_calls(self) -> None:
+        """Count function call sites by parsing disassembly output.
+
+        Parses direct call instructions (call0/call8/bl/blx) from objdump -d
+        to count how many times each function is called. This helps identify
+        inlining candidates — frequently called small functions benefit most
+        from inlining.
+        """
+        result = run_tool(
+            [self.objdump_path, "-d", str(self.elf_path)],
+            timeout=60,
+        )
+        if result is None or result.returncode != 0:
+            _LOGGER.debug("Failed to disassemble ELF for function call analysis")
+            return
+
+        self._function_call_counts = Counter(
+            match.group(1)
+            for line in result.stdout.splitlines()
+            if (match := _CALL_TARGET_PATTERN.search(line))
+        )
+
+        # Demangle any call targets not already in the cache
+        missing = [
+            name
+            for name in self._function_call_counts
+            if name not in self._demangle_cache
+        ]
+        if missing:
+            self._batch_demangle_symbols(missing)
+
+        _LOGGER.debug(
+            "Function call analysis: %d unique targets, %d total calls",
+            len(self._function_call_counts),
+            sum(self._function_call_counts.values()),
+        )
+
     def get_unattributed_ram(self) -> tuple[int, int, int]:
         """Get unattributed RAM sizes (SDK/framework overhead).
 

esphome/analyze_memory/cli.py

@@ -231,6 +231,110 @@ class MemoryAnalyzerCLI(MemoryAnalyzer):
                     lines.append(f"    {size:>6,} B  {sym_name}")
             lines.append("")
 
+    # Number of top called functions to show
+    TOP_CALLS_LIMIT: int = 50
+    # Number of inlining candidates to show
+    INLINE_CANDIDATES_LIMIT: int = 25
+    # Maximum function size in bytes to consider for inlining
+    INLINE_SIZE_THRESHOLD: int = 16
+
+    def _build_symbol_sizes(self) -> dict[str, int]:
+        """Build a size lookup from all component symbols: mangled_name -> size."""
+        return {
+            symbol: size
+            for symbols in self._component_symbols.values()
+            for symbol, _, size, _ in symbols
+        }
+
+    def _format_call_row(
+        self, index: int, mangled: str, count: int, symbol_sizes: dict[str, int]
+    ) -> str:
+        """Format a single row for call frequency tables."""
+        demangled = self._demangle_cache.get(mangled, mangled)
+        if len(demangled) > 80:
+            demangled = f"{demangled[:77]}..."
+        size = symbol_sizes.get(mangled)
+        size_str = f"{size:>5,} B" if size is not None else "      ?"
+        return f"{index:>3}  {count:>5}  {size_str}  {demangled}"
+
+    def _add_call_table_header(self, lines: list[str]) -> None:
+        """Add the header row for call frequency tables."""
+        lines.append(f"{'#':>3}  {'Calls':>5}  {'Size':>7}  Function")
+        lines.append(f"{'---':>3}  {'-----':>5}  {'-------':>7}  {'-' * 60}")
+
+    def _add_function_call_analysis(self, lines: list[str]) -> None:
+        """Add function call frequency analysis section.
+
+        Shows the most frequently called functions by call site count.
+        """
+        self._add_section_header(lines, "Top Called Functions")
+
+        symbol_sizes = self._build_symbol_sizes()
+
+        # Sort by call count descending
+        sorted_calls = sorted(
+            self._function_call_counts.items(), key=lambda x: x[1], reverse=True
+        )
+
+        self._add_call_table_header(lines)
+
+        for i, (mangled, count) in enumerate(sorted_calls[: self.TOP_CALLS_LIMIT]):
+            lines.append(self._format_call_row(i + 1, mangled, count, symbol_sizes))
+
+        total_calls = sum(self._function_call_counts.values())
+        lines.append("")
+        lines.append(
+            f"Total: {len(self._function_call_counts)} unique targets, "
+            f"{total_calls:,} call sites"
+        )
+        lines.append("")
+
+    def _add_inline_candidates(self, lines: list[str]) -> None:
+        """Add inlining candidates section.
+
+        Shows frequently called functions that are small enough to benefit
+        from inlining (< 16 bytes). These are the best candidates for
+        reducing call overhead.
+        """
+        self._add_section_header(
+            lines,
+            f"Inlining Candidates (<{self.INLINE_SIZE_THRESHOLD} B, by call count)",
+        )
+
+        symbol_sizes = self._build_symbol_sizes()
+
+        # Filter to small functions with known size, sort by call count
+        candidates = sorted(
+            (
+                (mangled, count)
+                for mangled, count in self._function_call_counts.items()
+                if mangled in symbol_sizes
+                and symbol_sizes[mangled] < self.INLINE_SIZE_THRESHOLD
+            ),
+            key=lambda x: x[1],
+            reverse=True,
+        )
+
+        if not candidates:
+            lines.append("No candidates found.")
+            lines.append("")
+            return
+
+        self._add_call_table_header(lines)
+
+        for i, (mangled, count) in enumerate(
+            candidates[: self.INLINE_CANDIDATES_LIMIT]
+        ):
+            lines.append(self._format_call_row(i + 1, mangled, count, symbol_sizes))
+
+        lines.append("")
+        lines.append(
+            f"Showing top {min(len(candidates), self.INLINE_CANDIDATES_LIMIT)} "
+            f"of {len(candidates)} functions under "
+            f"{self.INLINE_SIZE_THRESHOLD} B"
+        )
+        lines.append("")
+
     def generate_report(self, detailed: bool = False) -> str:
         """Generate a formatted memory report."""
         components = sorted(
@@ -533,6 +637,11 @@ class MemoryAnalyzerCLI(MemoryAnalyzer):
         if self._cswtch_symbols:
             self._add_cswtch_analysis(lines)
 
+        # Function call frequency analysis
+        if self._function_call_counts:
+            self._add_function_call_analysis(lines)
+            self._add_inline_candidates(lines)
+
         lines.append(
             "Note: This analysis covers symbols in the ELF file. Some runtime allocations may not be included."
         )