From 22414eb9023131ff79745f880ac77a1cf9a8f95d Mon Sep 17 00:00:00 2001
From: "Eliyaan (Nopana)" <103932369+Eliyaan@users.noreply.github.com>
Date: Fri, 28 Mar 2025 11:41:23 +0100
Subject: [PATCH] cgen: support measuring programs, that use multiple threads
 in the new profiler column (turn `prof_measured_time` into a thread local,
 for the supported C compilers) (#24061)

---
 vlib/v/gen/c/cgen.v    | 21 ++++++++++++++++++++-
 vlib/v/gen/c/profile.v | 10 +++++-----
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index a0228714c..1b03aa3a5 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -574,7 +574,26 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 	b.write_string2('\n // V preincludes:\n', g.preincludes.str())
 	b.write_string2('\n// V cheaders:\n', g.cheaders.str())
 	if g.pcs_declarations.len > 0 {
-		g.pcs_declarations.writeln('double prof_measured_time = 0.0;') // does not work for multithreaded
+		g.pcs_declarations.writeln('// V profile thread local:')
+		g.pcs_declarations.writeln('#if defined(__cplusplus) && __cplusplus >= 201103L')
+		g.pcs_declarations.writeln('\t#define PROF_THREAD_LOCAL thread_local')
+		g.pcs_declarations.writeln('#elif defined(__GNUC__) && __GNUC__ < 5')
+		g.pcs_declarations.writeln('\t#define PROF_THREAD_LOCAL __thread')
+		g.pcs_declarations.writeln('#elif defined(_MSC_VER)')
+		g.pcs_declarations.writeln('\t#define PROF_THREAD_LOCAL __declspec(thread)')
+		g.pcs_declarations.writeln('#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_THREADS__)')
+		g.pcs_declarations.writeln('\t#define PROF_THREAD_LOCAL _Thread_local')
+		g.pcs_declarations.writeln('#endif')
+		g.pcs_declarations.writeln('#ifndef PROF_THREAD_LOCAL')
+		g.pcs_declarations.writeln('\t#if defined(__GNUC__)')
+		g.pcs_declarations.writeln('\t\t#define PROF_THREAD_LOCAL __thread')
+		g.pcs_declarations.writeln('\t#endif')
+		g.pcs_declarations.writeln('#endif')
+		g.pcs_declarations.writeln('#ifdef PROF_THREAD_LOCAL')
+		g.pcs_declarations.writeln('\tstatic PROF_THREAD_LOCAL double prof_measured_time = 0.0;')
+		g.pcs_declarations.writeln('#else')
+		g.pcs_declarations.writeln('\tdouble prof_measured_time = 0.0; // multithreaded: wrong values for func times without its children')
+		g.pcs_declarations.writeln('#endif')
 		b.write_string2('\n// V profile counters:\n', g.pcs_declarations.str())
 	}
 	b.write_string2('\n// V includes:\n', g.includes.str())
diff --git a/vlib/v/gen/c/profile.v b/vlib/v/gen/c/profile.v
index e17075274..2da6d75c9 100644
--- a/vlib/v/gen/c/profile.v
+++ b/vlib/v/gen/c/profile.v
@@ -33,12 +33,12 @@ fn (mut g Gen) profile_fn(fn_decl ast.FnDecl) {
 		}
 		g.writeln('\tdouble _PROF_FN_START = ${measure_fn_name}();')
 		g.writeln('\tdouble _PROF_PREV_MEASURED_TIME = prof_measured_time;')
-		g.writeln('\tif(v__profile_enabled) { ${fn_profile_counter_name_calls}++; } // ${fn_name}')
+		g.writeln('if(v__profile_enabled) { ${fn_profile_counter_name_calls}++; } // ${fn_name}')
 		g.writeln('')
-		g.defer_profile_code = '\tif(v__profile_enabled) { double _PROF_ELAPSED = ${measure_fn_name}() - _PROF_FN_START; '
-		g.defer_profile_code += '${fn_profile_counter_name} += _PROF_ELAPSED; '
-		g.defer_profile_code += '${fn_profile_counter_name}_only_current += _PROF_ELAPSED - (prof_measured_time - _PROF_PREV_MEASURED_TIME); '
-		g.defer_profile_code += 'prof_measured_time = _PROF_PREV_MEASURED_TIME + _PROF_ELAPSED; }'
+		g.defer_profile_code = '\tif(v__profile_enabled) { \n\t\tdouble _PROF_ELAPSED = ${measure_fn_name}() - _PROF_FN_START;\n'
+		g.defer_profile_code += '\t\t${fn_profile_counter_name} += _PROF_ELAPSED;\n'
+		g.defer_profile_code += '\t\t${fn_profile_counter_name}_only_current += _PROF_ELAPSED - (prof_measured_time - _PROF_PREV_MEASURED_TIME);\n'
+		g.defer_profile_code += '\t\tprof_measured_time = _PROF_PREV_MEASURED_TIME + _PROF_ELAPSED;\n\t}'
 		if should_restore_v__profile_enabled {
 			g.defer_profile_code += '\n\t\tv__profile_enabled = _prev_v__profile_enabled;'
 		}
-- 
2.39.5