From 10187d2372d3cf26bf0d886a4a88e536d8fd13d2 Mon Sep 17 00:00:00 2001
From: Olivier Nicole <olivier@chnik.fr>
Date: Thu, 2 Mar 2023 14:22:59 +0100
Subject: [PATCH] Disable some TSan instrumentation for performance

The functions that we un-instrumentation are called often but should not
contain data races with user code.

Co-authored-by: Fabrice Buoro <fabrice@tarides.com>
---
 runtime/caml/mlvalues.h | 7 +++++--
 runtime/interp.c        | 2 ++
 runtime/minor_gc.c      | 2 ++
 runtime/shared_heap.c   | 1 +
 runtime/str.c           | 1 +
 5 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/runtime/caml/mlvalues.h b/runtime/caml/mlvalues.h
index 8332d1fe7f..448232680f 100644
--- a/runtime/caml/mlvalues.h
+++ b/runtime/caml/mlvalues.h
@@ -193,8 +193,11 @@ where 0 <= R <= 31 is HEADER_RESERVED_BITS, set with the
 #endif
 
 #define Hp_atomic_val(val) ((atomic_uintnat *)(val) - 1)
-#define Hd_val(val) ((header_t) \
-  (atomic_load_explicit(Hp_atomic_val(val), memory_order_relaxed)))
+CAMLno_user_tsan /* Disable TSan instrumentation for performance. */
+Caml_inline header_t Hd_val(value val)
+{
+  return atomic_load_explicit(Hp_atomic_val(val), memory_order_relaxed);
+}
 
 #define Color_val(val) (Color_hd (Hd_val (val)))
 
diff --git a/runtime/interp.c b/runtime/interp.c
index d206d87822..5f47101d3c 100644
--- a/runtime/interp.c
+++ b/runtime/interp.c
@@ -244,6 +244,8 @@ static value raise_unhandled_effect;
 
 /* The interpreter itself */
 
+CAMLno_user_tsan /* No need to TSan-instrument this (and pay a slowdown)
+                    function as TSan is not supported for bytecode. */
 value caml_interprete(code_t prog, asize_t prog_size)
 {
 #ifdef PC_REG
diff --git a/runtime/minor_gc.c b/runtime/minor_gc.c
index d063f9f518..8bfe6dd70e 100644
--- a/runtime/minor_gc.c
+++ b/runtime/minor_gc.c
@@ -171,6 +171,7 @@ static void spin_on_header(value v) {
   }
 }
 
+CAMLno_user_tsan /* Disable TSan instrumentation for performance. */
 Caml_inline header_t get_header_val(value v) {
   header_t hd = atomic_load_explicit(Hp_atomic_val(v), memory_order_acquire);
   if (!Is_update_in_progress(hd))
@@ -381,6 +382,7 @@ static void oldify_one (void* st_v, value v, volatile value *p)
    Note that [oldify_one] itself is called by oldify_mopup, so we
    have to be careful to remove the first entry from the list before
    oldifying its fields. */
+CAMLno_user_tsan /* Disable TSan instrumentation for performance. */
 static void oldify_mopup (struct oldify_state* st, int do_ephemerons)
 {
   value v, new_v, f;
diff --git a/runtime/shared_heap.c b/runtime/shared_heap.c
index 5e6568dc55..b7ae0b66d3 100644
--- a/runtime/shared_heap.c
+++ b/runtime/shared_heap.c
@@ -256,6 +256,7 @@ Caml_inline void pool_initialize(pool* r,
 }
 
 /* Allocating an object from a pool */
+CAMLno_user_tsan /* Disable TSan instrumentation for performance. */
 static intnat pool_sweep(struct caml_heap_state* local,
                          pool**,
                          sizeclass sz ,
diff --git a/runtime/str.c b/runtime/str.c
index 32ca54c7a5..fc9cee585e 100644
--- a/runtime/str.c
+++ b/runtime/str.c
@@ -268,6 +268,7 @@ CAMLprim value caml_bytes_set64(value str, value index, value newval)
   return Val_unit;
 }
 
+CAMLno_user_tsan /* Disable TSan instrumentation for performance. */
 CAMLprim value caml_string_equal(value s1, value s2)
 {
   mlsize_t sz1, sz2;