allocation profiler: get stacks for pool allocs via wrapper function (J…

…uliaLang#43868)

src/array.c

@@ -500,15 +500,17 @@ JL_DLLEXPORT jl_value_t *jl_alloc_string(size_t len)
         int pool_id = jl_gc_szclass_align8(allocsz);
         jl_gc_pool_t *p = &ptls->heap.norm_pools[pool_id];
         int osize = jl_gc_sizeclasses[pool_id];
-        s = jl_gc_pool_alloc(ptls, (char*)p - (char*)ptls, osize);
+        // We call `jl_gc_pool_alloc_noinline` instead of `jl_gc_pool_alloc` to avoid double-counting in
+        // the Allocations Profiler. (See https://github.com/JuliaLang/julia/pull/43868 for more details.)
+        s = jl_gc_pool_alloc_noinline(ptls, (char*)p - (char*)ptls, osize);
     }
     else {
         if (allocsz < sz) // overflow in adding offs, size was "negative"
             jl_throw(jl_memory_exception);
         s = jl_gc_big_alloc(ptls, allocsz);
     }
     jl_set_typeof(s, jl_string_type);
-    maybe_record_alloc_to_profile(s, len);
+    maybe_record_alloc_to_profile(s, len, jl_string_type);
     *(size_t*)s = len;
     jl_string_data(s)[len] = 0;
     return s;

src/gc-alloc-profiler.cpp

@@ -118,7 +118,7 @@ JL_DLLEXPORT void jl_free_alloc_profile() {
 
 // == callback called into by the outside ==
 
-void _maybe_record_alloc_to_profile(jl_value_t *val, size_t size) JL_NOTSAFEPOINT {
+void _maybe_record_alloc_to_profile(jl_value_t *val, size_t size, jl_datatype_t *type) JL_NOTSAFEPOINT {
     auto& global_profile = g_alloc_profile;
     auto thread_id = jl_atomic_load_relaxed(&jl_current_task->tid);
     auto& profile = global_profile.per_thread_profiles[thread_id];
@@ -129,7 +129,6 @@ void _maybe_record_alloc_to_profile(jl_value_t *val, size_t size) JL_NOTSAFEPOIN
         return;
     }
 
-    auto type = (jl_datatype_t*)jl_typeof(val);
     profile.allocs.emplace_back(jl_raw_alloc_t{
         type,
         get_raw_backtrace(),

src/gc-alloc-profiler.h

@@ -31,13 +31,15 @@ JL_DLLEXPORT void jl_free_alloc_profile(void);
 // Functions to call from GC when alloc profiling is enabled
 // ---------------------------------------------------------------------
 
-void _maybe_record_alloc_to_profile(jl_value_t *val, size_t size) JL_NOTSAFEPOINT;
+void _maybe_record_alloc_to_profile(jl_value_t *val, size_t size, jl_datatype_t *typ) JL_NOTSAFEPOINT;
 
 extern int g_alloc_profile_enabled;
 
-static inline void maybe_record_alloc_to_profile(jl_value_t *val, size_t size) JL_NOTSAFEPOINT {
+#define jl_gc_unknown_type_tag ((jl_datatype_t*)0xdeadaa03)
+
+static inline void maybe_record_alloc_to_profile(jl_value_t *val, size_t size, jl_datatype_t *typ) JL_NOTSAFEPOINT {
     if (__unlikely(g_alloc_profile_enabled)) {
-        _maybe_record_alloc_to_profile(val, size);
+        _maybe_record_alloc_to_profile(val, size, typ);
     }
 }
 

src/gc.c

@@ -1197,7 +1197,7 @@ static NOINLINE jl_taggedvalue_t *add_page(jl_gc_pool_t *p) JL_NOTSAFEPOINT
 }
 
 // Size includes the tag and the tag is not cleared!!
-JL_DLLEXPORT jl_value_t *jl_gc_pool_alloc(jl_ptls_t ptls, int pool_offset,
+static inline jl_value_t *jl_gc_pool_alloc_inner(jl_ptls_t ptls, int pool_offset,
                                           int osize)
 {
     // Use the pool offset instead of the pool address as the argument
@@ -1253,6 +1253,23 @@ JL_DLLEXPORT jl_value_t *jl_gc_pool_alloc(jl_ptls_t ptls, int pool_offset,
     return jl_valueof(v);
 }
 
+// Instrumented version of jl_gc_pool_alloc_inner, called into by LLVM-generated code.
+JL_DLLEXPORT jl_value_t *jl_gc_pool_alloc(jl_ptls_t ptls, int pool_offset,
+                                          int osize)
+{
+    jl_value_t *val = jl_gc_pool_alloc_inner(ptls, pool_offset, osize);
+
+    maybe_record_alloc_to_profile(val, osize, jl_gc_unknown_type_tag);
+    return val;
+}
+
+// This wrapper exists only to prevent `jl_gc_pool_alloc_inner` from being inlined into
+// its callers. We provide an external-facing interface for callers, and inline `jl_gc_pool_alloc_inner`
+// into this. (See https://github.com/JuliaLang/julia/pull/43868 for more details.)
+jl_value_t *jl_gc_pool_alloc_noinline(jl_ptls_t ptls, int pool_offset, int osize) {
+    return jl_gc_pool_alloc_inner(ptls, pool_offset, osize);
+}
+
 int jl_gc_classify_pools(size_t sz, int *osize)
 {
     if (sz > GC_MAX_SZCLASS)
@@ -3540,6 +3557,8 @@ JL_DLLEXPORT void *jl_gc_managed_malloc(size_t sz)
     SetLastError(last_error);
 #endif
     errno = last_errno;
+    // jl_gc_managed_malloc is currently always used for allocating array buffers.
+    maybe_record_alloc_to_profile(b, sz, (jl_datatype_t*)jl_buff_tag);
     return b;
 }
 
@@ -3581,7 +3600,7 @@ static void *gc_managed_realloc_(jl_ptls_t ptls, void *d, size_t sz, size_t olds
     SetLastError(last_error);
 #endif
     errno = last_errno;
-
+    maybe_record_alloc_to_profile(b, sz, jl_gc_unknown_type_tag);
     return b;
 }
 

src/julia_internal.h

@@ -229,8 +229,8 @@ extern jl_array_t *jl_all_methods JL_GLOBALLY_ROOTED;
 JL_DLLEXPORT extern int jl_lineno;
 JL_DLLEXPORT extern const char *jl_filename;
 
-JL_DLLEXPORT jl_value_t *jl_gc_pool_alloc(jl_ptls_t ptls, int pool_offset,
-                                          int osize);
+jl_value_t *jl_gc_pool_alloc_noinline(jl_ptls_t ptls, int pool_offset,
+                                   int osize);
 JL_DLLEXPORT jl_value_t *jl_gc_big_alloc(jl_ptls_t ptls, size_t allocsz);
 JL_DLLEXPORT int jl_gc_classify_pools(size_t sz, int *osize);
 extern uv_mutex_t gc_perm_lock;
@@ -358,15 +358,17 @@ STATIC_INLINE jl_value_t *jl_gc_alloc_(jl_ptls_t ptls, size_t sz, void *ty)
         int pool_id = jl_gc_szclass(allocsz);
         jl_gc_pool_t *p = &ptls->heap.norm_pools[pool_id];
         int osize = jl_gc_sizeclasses[pool_id];
-        v = jl_gc_pool_alloc(ptls, (char*)p - (char*)ptls, osize);
+        // We call `jl_gc_pool_alloc_noinline` instead of `jl_gc_pool_alloc` to avoid double-counting in
+        // the Allocations Profiler. (See https://github.com/JuliaLang/julia/pull/43868 for more details.)
+        v = jl_gc_pool_alloc_noinline(ptls, (char*)p - (char*)ptls, osize);
     }
     else {
         if (allocsz < sz) // overflow in adding offs, size was "negative"
             jl_throw(jl_memory_exception);
         v = jl_gc_big_alloc(ptls, allocsz);
     }
     jl_set_typeof(v, ty);
-    maybe_record_alloc_to_profile(v, sz);
+    maybe_record_alloc_to_profile(v, sz, (jl_datatype_t*)ty);
     return v;
 }
 

stdlib/Profile/src/Allocs.jl

@@ -163,15 +163,19 @@ const BacktraceCache = Dict{BTElement,Vector{StackFrame}}
 
 # copied from julia_internal.h
 const JL_BUFF_TAG = UInt(0x4eadc000)
+const JL_GC_UNKNOWN_TYPE_TAG = UInt(0xdeadaa03)
 
 struct CorruptType end
 struct BufferType end
+struct UnknownType end
 
 function load_type(ptr::Ptr{Type})
     if UInt(ptr) < UInt(4096)
         return CorruptType
     elseif UInt(ptr) == JL_BUFF_TAG
         return BufferType
+    elseif UInt(ptr) == JL_GC_UNKNOWN_TYPE_TAG
+        return UnknownType
     end
     return unsafe_pointer_to_objref(ptr)
 end