Add @min_optlevel to set a min-optlevel for a module

NEWS.md

@@ -23,6 +23,9 @@ New language features
   - actual running time for the task (`Base.Experimental.task_running_time_ns`), and
   - wall-time for the task (`Base.Experimental.task_wall_time_ns`).
 - Support for Unicode 16 ([#56925]).
+* `Base.Experimental.@min_optlevel level` sets a minimum optlevel (`--min_optlevel`) for a
+  module, ensuring that level of optimization even if the process is run at a lower optlevel
+  (`-O`) ([#]).
 
 Language changes
 ----------------

base/experimental.jl

@@ -124,6 +124,27 @@ macro optlevel(n::Int)
     return Expr(:meta, :optlevel, n)
 end
 
+"""
+    Experimental.@min_optlevel n::Int
+
+Set the minimum optimization level (equivalent to the `--min-optlevel` command line
+argument) for code in the current module. Submodules inherit the setting of their
+parent module.
+
+Supported values are 0, 1, 2, and 3.
+
+This sets a lower-bound for optimization level, such that the effective optimization
+level, `o` is `@min_optlevel <= o <= @optlevel` and `--min-optlevel <= o <= -O`.
+
+NOTE: This min optimization level will only be applied to LLVM functions that are compiled
+from this module. If a function defined in this module is *inlined* into a function defined
+outside the module, that function will not inherit this min optimization level. Consider
+whether you need to introduce `@noinline` if you require users to observe your min optlevel.
+"""
+macro min_optlevel(n::Int)
+    return Expr(:meta, :min_optlevel, n)
+end
+
 """
     Experimental.@max_methods n::Int
 

src/ast.c

@@ -100,6 +100,7 @@ JL_DLLEXPORT jl_sym_t *jl_escape_sym;
 JL_DLLEXPORT jl_sym_t *jl_aliasscope_sym;
 JL_DLLEXPORT jl_sym_t *jl_popaliasscope_sym;
 JL_DLLEXPORT jl_sym_t *jl_optlevel_sym;
+JL_DLLEXPORT jl_sym_t *jl_min_optlevel_sym;
 JL_DLLEXPORT jl_sym_t *jl_thismodule_sym;
 JL_DLLEXPORT jl_sym_t *jl_eval_sym;
 JL_DLLEXPORT jl_sym_t *jl_include_sym;
@@ -392,6 +393,7 @@ void jl_init_common_symbols(void)
     jl_specialize_sym = jl_symbol("specialize");
     jl_nospecializeinfer_sym = jl_symbol("nospecializeinfer");
     jl_optlevel_sym = jl_symbol("optlevel");
+    jl_min_optlevel_sym = jl_symbol("min_optlevel");
     jl_compile_sym = jl_symbol("compile");
     jl_force_compile_sym = jl_symbol("force_compile");
     jl_infer_sym = jl_symbol("infer");

src/codegen.cpp

@@ -8673,6 +8673,11 @@ static jl_llvm_functions_t
         static const char* const optLevelStrings[] = { "0", "1", "2", "3" };
         FnAttrs.addAttribute("julia-optimization-level", optLevelStrings[optlevel]);
     }
+    int min_optlevel = jl_get_module_min_optlevel(ctx.module);
+    if (min_optlevel >= 0 && min_optlevel <= 3) {
+        static const char* const optLevelStrings[] = { "0", "1", "2", "3" };
+        FnAttrs.addAttribute("julia-min-optimization-level", optLevelStrings[min_optlevel]);
+    }
 
     ctx.f = f;
 

src/interpreter.c

@@ -659,6 +659,12 @@ static jl_value_t *eval_body(jl_array_t *stmts, interpreter_state *s, size_t ip,
                                 jl_set_module_optlevel(s->module, n);
                             }
                         }
+                        else if (jl_exprarg(stmt, 0) == (jl_value_t*)jl_min_optlevel_sym) {
+                            if (jl_is_long(jl_exprarg(stmt, 1))) {
+                                int n = jl_unbox_long(jl_exprarg(stmt, 1));
+                                jl_set_module_min_optlevel(s->module, n);
+                            }
+                        }
                         else if (jl_exprarg(stmt, 0) == (jl_value_t*)jl_compile_sym) {
                             if (jl_is_long(jl_exprarg(stmt, 1))) {
                                 jl_set_module_compile(s->module, jl_unbox_long(jl_exprarg(stmt, 1)));

src/jitlayers.cpp

@@ -1049,6 +1049,14 @@ static orc::ThreadSafeModule selectOptLevel(orc::ThreadSafeModule TSM) JL_NOTSAF
                         if (ol < opt_level)
                             opt_level = ol;
                     }
+                    attr = F.getFnAttribute("julia-min-optimization-level");
+                    val = attr.getValueAsString();
+                    if (val != "") {
+                        size_t ol = (size_t)val[0] - '0';
+                        if (ol > opt_level)
+                            opt_level = ol;
+                        jl_safe_printf("Function %s opt: %d\n", F.getName().str().c_str(), (int)opt_level);
+                    }
                 }
             }
             if (opt_level < opt_level_min)

src/jl_exported_funcs.inc

@@ -213,6 +213,7 @@
     XX(jl_get_module_infer) \
     XX(jl_get_module_of_binding) \
     XX(jl_get_module_optlevel) \
+    XX(jl_get_module_min_optlevel) \
     XX(jl_get_next_task) \
     XX(jl_get_nth_field) \
     XX(jl_get_nth_field_checked) \
@@ -411,6 +412,7 @@
     XX(jl_set_module_infer) \
     XX(jl_set_module_nospecialize) \
     XX(jl_set_module_optlevel) \
+    XX(jl_set_module_min_optlevel) \
     XX(jl_set_module_uuid) \
     XX(jl_set_next_task) \
     XX(jl_set_nth_field) \

src/julia.h

@@ -724,6 +724,7 @@ typedef struct _jl_module_t {
     _Atomic(uint32_t) counter;
     int32_t nospecialize;  // global bit flags: initialization for new methods
     int8_t optlevel;
+    int8_t min_optlevel;
     int8_t compile;
     int8_t infer;
     uint8_t istopmod;
@@ -1989,7 +1990,9 @@ extern JL_DLLIMPORT jl_module_t *jl_libdl_module JL_GLOBALLY_ROOTED;
 JL_DLLEXPORT jl_module_t *jl_new_module(jl_sym_t *name, jl_module_t *parent);
 JL_DLLEXPORT void jl_set_module_nospecialize(jl_module_t *self, int on);
 JL_DLLEXPORT void jl_set_module_optlevel(jl_module_t *self, int lvl);
+JL_DLLEXPORT void jl_set_module_min_optlevel(jl_module_t *self, int lvl);
 JL_DLLEXPORT int jl_get_module_optlevel(jl_module_t *m);
+JL_DLLEXPORT int jl_get_module_min_optlevel(jl_module_t *m);
 JL_DLLEXPORT void jl_set_module_compile(jl_module_t *self, int value);
 JL_DLLEXPORT int jl_get_module_compile(jl_module_t *m);
 JL_DLLEXPORT void jl_set_module_infer(jl_module_t *self, int value);

src/julia_internal.h

@@ -1867,6 +1867,7 @@ extern JL_DLLEXPORT jl_sym_t *jl_escape_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_aliasscope_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_popaliasscope_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_optlevel_sym;
+extern JL_DLLEXPORT jl_sym_t *jl_min_optlevel_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_thismodule_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_eval_sym;
 extern JL_DLLEXPORT jl_sym_t *jl_include_sym;

src/module.c

@@ -91,6 +91,7 @@ JL_DLLEXPORT jl_module_t *jl_new_module_(jl_sym_t *name, jl_module_t *parent, ui
     jl_atomic_store_relaxed(&m->counter, 1);
     m->nospecialize = 0;
     m->optlevel = -1;
+    m->min_optlevel = -1;
     m->compile = -1;
     m->infer = -1;
     m->max_methods = -1;
@@ -145,6 +146,10 @@ JL_DLLEXPORT void jl_set_module_optlevel(jl_module_t *self, int lvl)
 {
     self->optlevel = lvl;
 }
+JL_DLLEXPORT void jl_set_module_min_optlevel(jl_module_t *self, int lvl)
+{
+    self->min_optlevel = lvl;
+}
 
 JL_DLLEXPORT int jl_get_module_optlevel(jl_module_t *m)
 {
@@ -155,6 +160,16 @@ JL_DLLEXPORT int jl_get_module_optlevel(jl_module_t *m)
     }
     return lvl;
 }
+JL_DLLEXPORT int jl_get_module_min_optlevel(jl_module_t *m)
+{
+    int lvl = m->min_optlevel;
+    while (lvl == -1 && m->parent != m && m != jl_base_module) {
+        m = m->parent;
+        lvl = m->min_optlevel;
+    }
+    return lvl;
+}
+
 
 JL_DLLEXPORT void jl_set_module_compile(jl_module_t *self, int value)
 {