Rewrite SendWithoutBlock to SendWithoutBlockDirect when possible

In calls to top-level functions, we assume that call targets will not
get rewritten, so we can insert a PatchPoint and do the lookup at
compile-time.

Author: tekknolagi

zjit/src/codegen.rs

@@ -187,7 +187,8 @@ fn gen_insn(jit: &mut JITState, asm: &mut Assembler, function: &Function, insn_i
         Insn::Jump(branch) => return gen_jump(jit, asm, branch),
         Insn::IfTrue { val, target } => return gen_if_true(jit, asm, opnd!(val), target),
         Insn::IfFalse { val, target } => return gen_if_false(jit, asm, opnd!(val), target),
-        Insn::SendWithoutBlock { call_info, cd, state, .. } => gen_send_without_block(jit, asm, call_info, *cd, function.frame_state(*state))?,
+        Insn::SendWithoutBlock { call_info, cd, state, .. } | Insn::SendWithoutBlockDirect { call_info, cd, state, .. }
+            => gen_send_without_block(jit, asm, call_info, *cd, function.frame_state(*state))?,
         Insn::Return { val } => return Some(gen_return(asm, opnd!(val))?),
         Insn::FixnumAdd { left, right, state } => gen_fixnum_add(asm, opnd!(left), opnd!(right), function.frame_state(*state))?,
         Insn::FixnumSub { left, right, state } => gen_fixnum_sub(asm, opnd!(left), opnd!(right), function.frame_state(*state))?,
@@ -200,6 +201,7 @@ fn gen_insn(jit: &mut JITState, asm: &mut Assembler, function: &Function, insn_i
         Insn::FixnumGe { left, right } => gen_fixnum_ge(asm, opnd!(left), opnd!(right))?,
         Insn::Test { val } => gen_test(asm, opnd!(val))?,
         Insn::GuardType { val, guard_type, state } => gen_guard_type(asm, opnd!(val), *guard_type, function.frame_state(*state))?,
+        Insn::GuardBitEquals { val, expected, state } => gen_guard_bit_equals(asm, opnd!(val), *expected, function.frame_state(*state))?,
         Insn::PatchPoint(_) => return Some(()), // For now, rb_zjit_bop_redefined() panics. TODO: leave a patch point and fix rb_zjit_bop_redefined()
         _ => {
             debug!("ZJIT: gen_function: unexpected insn {:?}", insn);
@@ -497,6 +499,13 @@ fn gen_guard_type(asm: &mut Assembler, val: lir::Opnd, guard_type: Type, state:
     Some(val)
 }
 
+/// Compile an identity check with a side exit
+fn gen_guard_bit_equals(asm: &mut Assembler, val: lir::Opnd, expected: VALUE, state: &FrameState) -> Option<lir::Opnd> {
+    asm.cmp(val, Opnd::UImm(expected.into()));
+    asm.jnz(Target::SideExit(state.clone()));
+    Some(val)
+}
+
 /// Save the incremented PC on the CFP.
 /// This is necessary when callees can raise or allocate.
 fn gen_save_pc(asm: &mut Assembler, state: &FrameState) {