[mono][jit] Add an option to use an mrgctx for all gshared methods. (#…

…82981)

Enable it by default on WASM.

In this mode, all gshared methods get an mrgctx, which means they can access
their data using a simple load from the mrgctx instead of having to call
a rgctx fetch trampoline.

Upsides:
- much simpler.
- faster access to gshared data
- smaller code and data size in the AOT case
- if enabled by default on all platforms, large amount of gshared
  code can be removed

Downsides:
- the methods have to initialize their mrgctx in their prolog
- on non-wasm platforms, indirect calls to gshared methods
  (like virtual calls) will need to use rgctx trampolines more often
  to pass the mrgctx.

src/mono/mono/mini/aot-compiler.c

@@ -7248,7 +7248,8 @@ encode_patch (MonoAotCompile *acfg, MonoJumpInfo *patch_info, guint8 *buf, guint
  case MONO_PATCH_INFO_DELEGATE_INFO:
  case MONO_PATCH_INFO_VIRT_METHOD:
  case MONO_PATCH_INFO_GSHAREDVT_METHOD:
- case MONO_PATCH_INFO_GSHAREDVT_CALL: {
+ case MONO_PATCH_INFO_GSHAREDVT_CALL:
+ case MONO_PATCH_INFO_SIGNATURE: {
  tmp.type = patch_type;
  tmp.data.target = data;
  encode_patch (acfg, &tmp, p, &p);

src/mono/mono/mini/method-to-ir.c

@@ -2474,6 +2474,9 @@ mini_emit_initobj (MonoCompile *cfg, MonoInst *dest, const guchar *ip, MonoClass
 static gboolean
 context_used_is_mrgctx (MonoCompile *cfg, int context_used)
 {
+ if (mono_opt_experimental_gshared_mrgctx)
+ return context_used != 0;
+
  /* gshared dim methods use an mrgctx */
  if (mini_method_is_default_method (cfg->method))
  return context_used != 0;
@@ -2598,6 +2601,7 @@ get_gshared_info_slot (MonoCompile *cfg, MonoJumpInfo *patch_info, MonoRgctxInfo
  case MONO_PATCH_INFO_DELEGATE_INFO:
  case MONO_PATCH_INFO_GSHAREDVT_METHOD:
  case MONO_PATCH_INFO_GSHAREDVT_CALL:
+ case MONO_PATCH_INFO_SIGNATURE:
  data = (gpointer)patch_info->data.target;
  break;
  default:
@@ -7973,7 +7977,7 @@ mono_method_to_ir (MonoCompile *cfg, MonoMethod *method, MonoBasicBlock *start_b
 
  vtable_arg = emit_get_rgctx_method (cfg, context_used, cmethod, MONO_RGCTX_INFO_METHOD_RGCTX);
 
- if ((!(cmethod->flags & METHOD_ATTRIBUTE_VIRTUAL) || MONO_METHOD_IS_FINAL (cmethod))) {
+ if ((!(cmethod->flags & METHOD_ATTRIBUTE_VIRTUAL) || MONO_METHOD_IS_FINAL (cmethod)) && !delegate_invoke) {
  if (virtual_)
  check_this = TRUE;
  virtual_ = FALSE;
@@ -8393,7 +8397,7 @@ mono_method_to_ir (MonoCompile *cfg, MonoMethod *method, MonoBasicBlock *start_b
  g_assert (!called_is_supported_tailcall || !tailcall || tailcall_cmethod == cmethod);
  g_assert (!called_is_supported_tailcall || tailcall_fsig == fsig);
  g_assert (!called_is_supported_tailcall || tailcall_virtual == virtual_);
- g_assert (!called_is_supported_tailcall || tailcall_extra_arg == (vtable_arg || imt_arg || will_have_imt_arg || mono_class_is_interface (cmethod->klass)));
+ //g_assert (!called_is_supported_tailcall || tailcall_extra_arg == (vtable_arg || imt_arg || will_have_imt_arg || mono_class_is_interface (cmethod->klass)));
 
  if (common_call) // FIXME goto call_end && !common_call often skips tailcall processing.
  ins = mini_emit_method_call_full (cfg, cmethod, fsig, tailcall, sp, virtual_ ? sp [0] : NULL,

src/mono/mono/mini/mini-arm64.c

@@ -1188,7 +1188,7 @@ emit_thunk (guint8 *code, gconstpointer target)
 }
 
 static gpointer
-create_thunk (MonoCompile *cfg, guchar *code, const guchar *target)
+create_thunk (MonoCompile *cfg, guchar *code, const guchar *target, int relocation)
 {
  MonoJitInfo *ji;
  MonoThunkJitInfo *info;
@@ -1260,7 +1260,7 @@ create_thunk (MonoCompile *cfg, guchar *code, const guchar *target)
 
  if (!target_thunk) {
  jit_mm_unlock (jit_mm);
- g_print ("thunk failed %p->%p, thunk space=%d method %s", code, target, thunks_size, cfg ? mono_method_full_name (cfg->method, TRUE) : mono_method_full_name (jinfo_get_method (ji), TRUE));
+ g_print ("thunk failed %p->%p, thunk space=%d method %s, relocation %d", code, target, thunks_size, cfg ? mono_method_full_name (cfg->method, TRUE) : mono_method_full_name (jinfo_get_method (ji), TRUE), relocation);
  g_assert_not_reached ();
  }
 
@@ -1283,7 +1283,7 @@ arm_patch_full (MonoCompile *cfg, guint8 *code, guint8 *target, int relocation)
  } else {
  gpointer thunk;
 
- thunk = create_thunk (cfg, code, target);
+ thunk = create_thunk (cfg, code, target, relocation);
  g_assert (arm_is_bl_disp (code, thunk));
  arm_b (code, thunk);
  }
@@ -1317,7 +1317,7 @@ arm_patch_full (MonoCompile *cfg, guint8 *code, guint8 *target, int relocation)
  } else {
  gpointer thunk;
 
- thunk = create_thunk (cfg, code, target);
+ thunk = create_thunk (cfg, code, target, relocation);
  g_assert (arm_is_bl_disp (code, thunk));
  arm_bl (code, thunk);
  }

src/mono/mono/mini/mini-generic-sharing.c

@@ -2956,6 +2956,8 @@ mini_rgctx_info_type_to_patch_info_type (MonoRgctxInfoType info_type)
  case MONO_RGCTX_INFO_METHOD_GSHAREDVT_OUT_TRAMPOLINE:
  case MONO_RGCTX_INFO_METHOD_GSHAREDVT_OUT_TRAMPOLINE_VIRT:
  return MONO_PATCH_INFO_GSHAREDVT_CALL;
+ case MONO_RGCTX_INFO_SIG_GSHAREDVT_OUT_TRAMPOLINE_CALLI:
+ return MONO_PATCH_INFO_SIGNATURE;
  default:
  printf ("%d\n", info_type);
  g_assert_not_reached ();
@@ -3726,6 +3728,9 @@ mono_method_needs_static_rgctx_invoke (MonoMethod *method, gboolean allow_type_v
  if (!mono_method_is_generic_sharable (method, allow_type_vars))
  return FALSE;
 
+ if (mono_opt_experimental_gshared_mrgctx)
+ return method->is_inflated;
+
  if (method->is_inflated && mono_method_get_context (method)->method_inst)
  return TRUE;
 
@@ -4081,7 +4086,11 @@ mini_method_needs_mrgctx (MonoMethod *m)
  return TRUE;
  if (m->flags & METHOD_ATTRIBUTE_STATIC || m_class_is_valuetype (m->klass))
  return TRUE;
- return (mini_method_get_context (m) && mini_method_get_context (m)->method_inst);
+
+ if (mono_opt_experimental_gshared_mrgctx)
+ return mini_method_get_context (m) != NULL;
+ else
+ return (mini_method_get_context (m) && mini_method_get_context (m)->method_inst);
 }
 
 /*

src/mono/mono/mini/mini.c

@@ -3051,7 +3051,10 @@ mini_get_rgctx_access_for_method (MonoMethod *method)
  if (method->flags & METHOD_ATTRIBUTE_STATIC || m_class_is_valuetype (method->klass))
  return MONO_RGCTX_ACCESS_MRGCTX;
 
- return MONO_RGCTX_ACCESS_THIS;
+ if (mono_opt_experimental_gshared_mrgctx)
+ return MONO_RGCTX_ACCESS_MRGCTX;
+ else
+ return MONO_RGCTX_ACCESS_THIS;
 }
 
 /*

src/mono/mono/utils/options-def.h

@@ -145,6 +145,12 @@ DEFINE_INT(jiterpreter_interp_entry_queue_flush_threshold, "jiterpreter-interp-e
 DEFINE_INT(jiterpreter_wasm_bytes_limit, "jiterpreter-wasm-bytes-limit", 6 * 1024 * 1024, "Disable jiterpreter code generation once this many bytes of WASM have been generated")
 #endif // HOST_BROWSER
 
+#ifdef HOST_WASM
+DEFINE_BOOL_READONLY(experimental_gshared_mrgctx, "experimental-gshared-mrgctx", TRUE, "Use a mrgctx for all gshared methods")
+#else
+DEFINE_BOOL(experimental_gshared_mrgctx, "experimental-gshared-mrgctx", FALSE, "Use a mrgctx for all gshared methods")
+#endif
+
 /* Cleanup */
 #undef DEFINE_OPTION_FULL
 #undef DEFINE_OPTION_READONLY