YJIT: implement `getconstant` YARV instruction (#6884)

* YJIT: implement getconstant YARV instruction

* Constant id is not a pointer

* Stack operands must be read after jit_prepare_routine_call

Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>

3 files changed, 65 insertions, 0 deletions

diff --git a/test/ruby/test_yjit.rb b/test/ruby/test_yjit.rb
index 1020257580..3a5792cab4 100644
--- a/test/ruby/test_yjit.rb
+++ b/test/ruby/test_yjit.rb
@@ -389,6 +389,29 @@ class TestYJIT < Test::Unit::TestCase
     assert_compiles("'foo' =~ /(o)./; $2", insns: %i[getspecial], result: nil)
   end
 
+  def test_compile_getconstant
+    assert_compiles(<<~RUBY, insns: %i[getconstant], result: [], call_threshold: 1)
+      def get_argv(klass)
+        klass::ARGV
+      end
+
+      get_argv(Object)
+    RUBY
+  end
+
+  def test_compile_getconstant_with_sp_offset
+    assert_compiles(<<~RUBY, insns: %i[getconstant], result: 2, call_threshold: 1)
+      class Foo
+        Bar = 1
+      end
+
+      2.times do
+        s = Foo # this opt_getconstant_path needs warmup, so 2.times is needed
+        Class.new(Foo).const_set(:Bar, s::Bar)
+      end
+    RUBY
+  end
+
   def test_compile_opt_getconstant_path
     assert_compiles(<<~RUBY, insns: %i[opt_getconstant_path], result: 123, call_threshold: 2)
       def get_foo
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 265088caac..1eed081fea 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1070,6 +1070,12 @@ vm_get_ev_const(rb_execution_context_t *ec, VALUE orig_klass, ID id, bool allow_
     }
 }
 
+VALUE
+rb_vm_get_ev_const(rb_execution_context_t *ec, VALUE orig_klass, ID id, VALUE allow_nil)
+{
+    return vm_get_ev_const(ec, orig_klass, id, allow_nil == Qtrue, 0);
+}
+
 static inline VALUE
 vm_get_ev_const_chain(rb_execution_context_t *ec, const ID *segments)
 {
diff --git a/yjit/src/codegen.rs b/yjit/src/codegen.rs
index d890775f2b..6a4026e947 100644
--- a/yjit/src/codegen.rs
+++ b/yjit/src/codegen.rs
@@ -6590,6 +6590,41 @@ fn gen_setclassvariable(
     KeepCompiling
 }
 
+fn gen_getconstant(
+    jit: &mut JITState,
+    ctx: &mut Context,
+    asm: &mut Assembler,
+    _ocb: &mut OutlinedCb,
+) -> CodegenStatus {
+
+    let id = jit_get_arg(jit, 0).as_usize();
+
+    // vm_get_ev_const can raise exceptions.
+    jit_prepare_routine_call(jit, ctx, asm);
+
+    let allow_nil_opnd = ctx.stack_pop(1);
+    let klass_opnd = ctx.stack_pop(1);
+
+    extern "C" {
+        fn rb_vm_get_ev_const(ec: EcPtr, klass: VALUE, id: ID, allow_nil: VALUE) -> VALUE;
+    }
+
+    let val_opnd = asm.ccall(
+        rb_vm_get_ev_const as *const u8,
+        vec![
+            EC,
+            klass_opnd,
+            id.into(),
+            allow_nil_opnd
+        ],
+    );
+
+    let top = ctx.stack_push(Type::Unknown);
+    asm.mov(top, val_opnd);
+
+    KeepCompiling
+}
+
 fn gen_opt_getconstant_path(
     jit: &mut JITState,
     ctx: &mut Context,
@@ -6993,6 +7028,7 @@ fn get_gen_fn(opcode: VALUE) -> Option<InsnGenFn> {
         YARVINSN_opt_size => Some(gen_opt_size),
         YARVINSN_opt_length => Some(gen_opt_length),
         YARVINSN_opt_regexpmatch2 => Some(gen_opt_regexpmatch2),
+        YARVINSN_getconstant => Some(gen_getconstant),
         YARVINSN_opt_getconstant_path => Some(gen_opt_getconstant_path),
         YARVINSN_invokebuiltin => Some(gen_invokebuiltin),
         YARVINSN_opt_invokebuiltin_delegate => Some(gen_opt_invokebuiltin_delegate),