Allow optional sorting of profiler output via HL_PROFILER_SORT env var (Fixes #7638)

src/runtime/profiler_common.cpp

@@ -333,6 +333,23 @@ WEAK void halide_profiler_memory_free(void *user_context,
 WEAK void halide_profiler_report_unlocked(void *user_context, halide_profiler_state *s) {
     StringStreamPrinter<1024> sstr(user_context);
 
+    int64_t (*compare_fs_fn)(halide_profiler_func_stats *a, halide_profiler_func_stats *b) = nullptr;
+
+    const char *sort_str = getenv("HL_PROFILER_SORT");
+    if (sort_str) {
+        if (!strcmp(sort_str, "time")) {
+            // Sort by descending time
+            compare_fs_fn = [](halide_profiler_func_stats *a, halide_profiler_func_stats *b) -> int64_t {
+                return (int64_t)b->time - (int64_t)a->time;
+            };
+        } else if (!strcmp(sort_str, "name")) {
+            // Sort by ascending name
+            compare_fs_fn = [](halide_profiler_func_stats *a, halide_profiler_func_stats *b) -> int64_t {
+                return strcmp(a->name, b->name);
+            };
+        }
+    }
+
     for (halide_profiler_pipeline_stats *p = s->pipelines; p;
          p = (halide_profiler_pipeline_stats *)(p->next)) {
         float t = p->time / 1000000.0f;
@@ -366,6 +383,9 @@ WEAK void halide_profiler_report_unlocked(void *user_context, halide_profiler_st
         }
 
         if (print_f_states) {
+            int f_stats_count = 0;
+            halide_profiler_func_stats **f_stats = (halide_profiler_func_stats **)__builtin_alloca(p->num_funcs * sizeof(halide_profiler_func_stats *));
+
             int max_func_name_length = 0;
             for (int i = 0; i < p->num_funcs; i++) {
                 halide_profiler_func_stats *fs = p->funcs + i;
@@ -376,8 +396,6 @@ WEAK void halide_profiler_report_unlocked(void *user_context, halide_profiler_st
             }
 
             for (int i = 0; i < p->num_funcs; i++) {
-                size_t cursor = 0;
-                sstr.clear();
                 halide_profiler_func_stats *fs = p->funcs + i;
 
                 // The first func is always a catch-all overhead
@@ -386,6 +404,25 @@ WEAK void halide_profiler_report_unlocked(void *user_context, halide_profiler_st
                     continue;
                 }
 
+                f_stats[f_stats_count++] = fs;
+            }
+
+            if (compare_fs_fn) {
+                for (int i = 1; i < f_stats_count; i++) {
+                    for (int j = i; j > 0 && compare_fs_fn(f_stats[j - 1], f_stats[j]) > 0; j--) {
+                        auto *a = f_stats[j - 1];
+                        auto *b = f_stats[j];
+                        f_stats[j - 1] = b;
+                        f_stats[j] = a;
+                    }
+                }
+            }
+
+            for (int i = 0; i < f_stats_count; i++) {
+                size_t cursor = 0;
+                sstr.clear();
+                halide_profiler_func_stats *fs = f_stats[i];
+
                 sstr << "  " << fs->name << ": ";
                 cursor += max_func_name_length + 5;
                 while (sstr.size() < cursor) {