Make safepoint emission on function entry a codegen feature

base/reflection.jl

@@ -1063,6 +1063,7 @@ struct CodegenParams
     prefer_specsig::Cint
     gnu_pubnames::Cint
     debug_info_kind::Cint
+    safepoint_on_entry::Cint
 
     lookup::Ptr{Cvoid}
 
@@ -1071,12 +1072,14 @@ struct CodegenParams
     function CodegenParams(; track_allocations::Bool=true, code_coverage::Bool=true,
                    prefer_specsig::Bool=false,
                    gnu_pubnames=true, debug_info_kind::Cint = default_debug_info_kind(),
+                   safepoint_on_entry::Bool=true,
                    lookup::Ptr{Cvoid}=cglobal(:jl_rettype_inferred),
                    generic_context = nothing)
         return new(
             Cint(track_allocations), Cint(code_coverage),
             Cint(prefer_specsig),
             Cint(gnu_pubnames), debug_info_kind,
+            Cint(safepoint_on_entry),
             lookup, generic_context)
     end
 end

src/codegen.cpp

@@ -905,7 +905,7 @@ extern "C" {
 #else
         1,
 #endif
-        jl_default_debug_info_kind,
+        jl_default_debug_info_kind, 1,
         jl_rettype_inferred, NULL };
 }
 
@@ -6893,7 +6893,8 @@ static std::pair<std::unique_ptr<Module>, jl_llvm_functions_t>
     Instruction &prologue_end = ctx.builder.GetInsertBlock()->back();
 
     // step 11a. Emit the entry safepoint
-    emit_safepoint(ctx);
+    if (JL_FEAT_TEST(ctx, safepoint_on_entry))
+        emit_safepoint(ctx);
 
     // step 11b. Do codegen in control flow order
     std::vector<int> workstack;

src/julia.h

@@ -2167,9 +2167,11 @@ typedef struct {
 
     // controls the emission of debug-info. mirrors the clang options
     int gnu_pubnames;       // can we emit the gnu pubnames debuginfo
-    int debug_info_kind; // Enum for line-table-only, line-directives-only,
+    int debug_info_kind;    // Enum for line-table-only, line-directives-only,
                             // limited, standalone
 
+    int safepoint_on_entry; // Emit a safepoint on entry to each function
+
     // Cache access. Default: jl_rettype_inferred.
     jl_codeinstance_lookup_t lookup;
 

test/compiler/codegen.jl

@@ -9,9 +9,12 @@ const opt_level = Base.JLOptions().opt_level
 const coverage = (Base.JLOptions().code_coverage > 0) || (Base.JLOptions().malloc_log > 0)
 const Iptr = sizeof(Int) == 8 ? "i64" : "i32"
 
-# `_dump_function` might be more efficient but it doesn't really matter here...
-get_llvm(@nospecialize(f), @nospecialize(t), raw=true, dump_module=false, optimize=true) =
-    sprint(code_llvm, f, t, raw, dump_module, optimize)
+# The tests below assume a certain format and safepoint_on_entry=true breaks that.
+function get_llvm(@nospecialize(f), @nospecialize(t), raw=true, dump_module=false, optimize=true)
+    params = Base.CodegenParams(safepoint_on_entry=false)
+    d = InteractiveUtils._dump_function(f, t, false, false, !raw, dump_module, :att, optimize, :none, false, params)
+    sprint(print, d)
+end
 
 if opt_level > 0
     # Make sure getptls call is removed at IR level with optimization on