experiment with allocating regs on stack in interp

+ Avoids having to lug around an execution context, arguably simplified
  things but now there's no real way to detect when we run out memory
  for regs.

1 files changed, 28 insertions, 77 deletions

diff --git a/src/interp.c b/src/interp.c
index f8ba927..80a9edc 100644
--- a/src/interp.c
+++ b/src/interp.c
@@ -5,7 +5,7 @@
 /* this is the body of a given ejit_interp function, it assumes there's an
  * external int64_t retval and double retval_f into which it places the value to
  * be returned. Included from src/interp.c */
-union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args[argc], struct interp_state *state, bool run, void ***labels_wb)
+union interp_ret ejit_run(struct ejit_func *f, size_t paramc, struct ejit_arg params[paramc], bool run, void ***labels_wb)
 {
 	static void *labels[OPCODE_COUNT] = {
 		[MOVI] = &&MOVI,
@@ -227,40 +227,35 @@ union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args
 	if (f->arena) {
 		if (f->rtype == EJIT_INT64 || f->rtype == EJIT_UINT64)
 			return (union interp_ret){
-				.i = ((ejit_escape_l_t)f->arena)(argc, args)
+				.i = ((ejit_escape_l_t)f->arena)(paramc, params)
 			};
 
 		if (f->rtype == EJIT_DOUBLE)
 			return (union interp_ret){
-				.f = ((ejit_escape_d_t)f->arena)(argc, args)
+				.f = ((ejit_escape_d_t)f->arena)(paramc, params)
 			};
 
 		if (f->rtype == EJIT_FLOAT)
 			return (union interp_ret){
-				.f = ((ejit_escape_f_t)f->arena)(argc, args)
+				.f = ((ejit_escape_f_t)f->arena)(paramc, params)
 			};
 
 		return (union interp_ret){
-			.i = ((ejit_escape_i_t)f->arena)(argc, args)
+			.i = ((ejit_escape_i_t)f->arena)(paramc, params)
 		};
 	}
 
 	int64_t retval = 0; double retval_f = 0.0;
 
-	size_t prev_gprs = gprs_len(&state->gprs);
-	size_t prev_fprs = fprs_len(&state->fprs);
-	size_t prev_argc = args_len(&state->args);
-
-	gprs_reserve(&state->gprs, prev_gprs + gpr_stats_len(&f->gpr));
-	fprs_reserve(&state->fprs, prev_fprs + fpr_stats_len(&f->fpr));
-
 	union fpr {
 		double d;
 		float f;
 	};
-	int64_t *gpr = ((int64_t *)state->gprs.buf) + prev_gprs;
-	union fpr *fpr = ((union fpr *)state->fprs.buf) + prev_fprs;
 
+	size_t argc = 0;
+	int64_t *gpr = alloca(sizeof(int64_t) * gpr_stats_len(&f->gpr));
+	union fpr *fpr = alloca(sizeof(int64_t) * fpr_stats_len(&f->fpr));
+	struct ejit_arg *args = alloca(sizeof(struct ejit_arg) * f->max_args);
 	struct ejit_insn *insns = f->insns.buf;
 
 	/* retval is kind of an unfortunate extra bit of state to keep track of,
@@ -978,25 +973,25 @@ union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args
 	DISPATCH();
 
 	DO(PARAM);
-	gpr[i.r2] = args[i.r0].u64;
+	gpr[i.r2] = params[i.r0].u64;
 	DISPATCH();
 
 	DO(PARAM_F);
 	if (i.r1 == EJIT_FLOAT)
-		fpr[i.r2].f = args[i.r0].f;
+		fpr[i.r2].f = params[i.r0].f;
 	else
-		fpr[i.r2].d = args[i.r0].d;
+		fpr[i.r2].d = params[i.r0].d;
 
 	DISPATCH();
 
 	DO(ARG);
 	struct ejit_arg a = ejit_build_arg(i.r1, gpr[i.r2]);
-	args_append(&state->args, a);
+	args[argc++] = a;
 	DISPATCH();
 
 	DO(ARG_I);
 	struct ejit_arg a = ejit_build_arg(i.r1, i.o);
-	args_append(&state->args, a);
+	args[argc++] = a;
 	DISPATCH();
 
 	DO(ARG_F);
@@ -1006,7 +1001,7 @@ union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args
 	else
 		a = ejit_build_arg_f(i.r1, fpr[i.r2].f);
 
-	args_append(&state->args, a);
+	args[argc++] = a;
 	DISPATCH();
 
 	DO(ARG_FI);
@@ -1016,95 +1011,55 @@ union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args
 	else
 		a = ejit_build_arg_f(i.r1, i.f);
 
-	args_append(&state->args, a);
+	args[argc++] = a;
 	DISPATCH();
 
 	DO(CALLI_I);
 	struct ejit_func *f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
-	retval = ejit_run(f, argc, args, state, true, NULL).i;
-
-	gpr = state->gprs.buf + prev_gprs;
-	fpr = (union fpr *)state->fprs.buf + prev_fprs;
-	args_shrink(&state->args, prev_argc);
+	retval = ejit_run(f, argc, args, true, NULL).i;
+	argc = 0;
 	DISPATCH();
 
 	DO(CALLI_L);
 	struct ejit_func *f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
-	retval = ejit_run(f, argc, args, state, true, NULL).i;
-
-	gpr = state->gprs.buf + prev_gprs;
-	fpr = (union fpr *)state->fprs.buf + prev_fprs;
-	args_shrink(&state->args, prev_argc);
+	retval = ejit_run(f, argc, args, true, NULL).i;
+	argc = 0;
 	DISPATCH();
 
 	DO(CALLI_F);
 	struct ejit_func *f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
-	retval_f = ejit_run(f, argc, args, state, true, NULL).f;
-
-	gpr = state->gprs.buf + prev_gprs;
-	fpr = (union fpr *)state->fprs.buf + prev_fprs;
-	args_shrink(&state->args, prev_argc);
+	retval_f = ejit_run(f, argc, args, true, NULL).f;
+	argc = 0;
 	DISPATCH();
 
 	DO(CALLI_D);
 	struct ejit_func *f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
-	retval_f = ejit_run(f, argc, args, state, true, NULL).f;
-
-	gpr = state->gprs.buf + prev_gprs;
-	fpr = (union fpr *)state->fprs.buf + prev_fprs;
-	args_shrink(&state->args, prev_argc);
+	retval_f = ejit_run(f, argc, args, true, NULL).f;
+	argc = 0;
 	DISPATCH();
 
 	DO(ESCAPEI_I);
 	ejit_escape_i_t f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
 	retval = f(argc, args);
-
-	args_shrink(&state->args, prev_argc);
+	argc = 0;
 	DISPATCH();
 
 	DO(ESCAPEI_L);
 	ejit_escape_l_t f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
 	retval = f(argc, args);
-
-	args_shrink(&state->args, prev_argc);
+	argc = 0;
 	DISPATCH();
 
 	DO(ESCAPEI_F);
 	ejit_escape_f_t f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
 	retval_f = f(argc, args);
-
-	args_shrink(&state->args, prev_argc);
+	argc = 0;
 	DISPATCH();
 
 	DO(ESCAPEI_D);
 	ejit_escape_d_t f = i.p;
-	size_t argc = args_len(&state->args) - prev_argc;
-	struct ejit_arg *args = state->args.buf + prev_argc;
-
 	retval_f = f(argc, args);
-
-	args_shrink(&state->args, prev_argc);
+	argc = 0;
 	DISPATCH();
 
 	/* dispatch is technically unnecessary for returns, but keep it for
@@ -1144,13 +1099,9 @@ union interp_ret ejit_run(struct ejit_func *f, size_t argc, struct ejit_arg args
 #undef DO
 
 out_float:
-	gprs_shrink(&state->gprs, prev_gprs);
-	fprs_shrink(&state->fprs, prev_fprs);
 	return (union interp_ret){.f = retval_f};
 
 out_int:
-	gprs_shrink(&state->gprs, prev_gprs);
-	fprs_shrink(&state->fprs, prev_fprs);
 	return (union interp_ret){.i = retval};
 
 zero_out: