# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1640457003 -3600
# Node ID b969fdb8cd4640605d4361432c6c6a4a2f29cec8
# Parent  71ae885c1426a04424f6d682a607c0a8bb883137
patch 8.2.3893: Vim9: many local variables are initialized with an instruction

Commit: https://github.com/vim/vim/commit/5cd647935d0834b3064aa36384b8f6730fadadd6
Author: Bram Moolenaar <Bram@vim.org>
Date:   Sat Dec 25 18:23:24 2021 +0000

    patch 8.2.3893: Vim9: many local variables are initialized with an instruction

    Problem:    Vim9: many local variables are initialized with an instruction.
    Solution:   Initialize local variables to zero to avoid the instructions.

diff --git a/src/proto/vim9instr.pro b/src/proto/vim9instr.pro
--- a/src/proto/vim9instr.pro
+++ b/src/proto/vim9instr.pro
@@ -65,7 +65,7 @@ int generate_UNPACK(cctx_T *cctx, int va
 int generate_cmdmods(cctx_T *cctx, cmdmod_T *cmod);
 int generate_undo_cmdmods(cctx_T *cctx);
 int generate_store_var(cctx_T *cctx, assign_dest_T dest, int opt_flags, int vimvaridx, int scriptvar_idx, int scriptvar_sid, type_T *type, char_u *name);
-int generate_store_lhs(cctx_T *cctx, lhs_T *lhs, int instr_count);
+int generate_store_lhs(cctx_T *cctx, lhs_T *lhs, int instr_count, int is_decl);
 void may_generate_prof_end(cctx_T *cctx, int prof_lnum);
 void delete_instr(isn_T *isn);
 void clear_instr_ga(garray_T *gap);
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -1773,6 +1773,7 @@ enddef
 def ReturnBool(): bool
   var one = 1
   var zero = 0
+  var none: number
   var name: bool = one && zero || one
   return name
 enddef
@@ -1783,19 +1784,19 @@ def Test_disassemble_return_bool()
         'var one = 1\_s*' ..
         '0 STORE 1 in $0\_s*' ..
         'var zero = 0\_s*' ..
-        '1 STORE 0 in $1\_s*' ..
+        'var none: number\_s*' ..
         'var name: bool = one && zero || one\_s*' ..
-        '2 LOAD $0\_s*' ..
-        '3 COND2BOOL\_s*' ..
-        '4 JUMP_IF_COND_FALSE -> 7\_s*' ..
-        '5 LOAD $1\_s*' ..
-        '6 COND2BOOL\_s*' ..
-        '7 JUMP_IF_COND_TRUE -> 10\_s*' ..
-        '8 LOAD $0\_s*' ..
-        '9 COND2BOOL\_s*' ..
-        '10 STORE $2\_s*' ..
+        '1 LOAD $0\_s*' ..
+        '2 COND2BOOL\_s*' ..
+        '3 JUMP_IF_COND_FALSE -> 6\_s*' ..
+        '4 LOAD $1\_s*' ..
+        '5 COND2BOOL\_s*' ..
+        '6 JUMP_IF_COND_TRUE -> 9\_s*' ..
+        '7 LOAD $0\_s*' ..
+        '8 COND2BOOL\_s*' ..
+        '9 STORE $3\_s*' ..
         'return name\_s*' ..
-        '\d\+ LOAD $2\_s*' ..   
+        '\d\+ LOAD $3\_s*' ..   
         '\d\+ RETURN',
         instr)
   assert_equal(true, InvertBool())
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3893,
+/**/
     3892,
 /**/
     3891,
diff --git a/src/vim9cmds.c b/src/vim9cmds.c
--- a/src/vim9cmds.c
+++ b/src/vim9cmds.c
@@ -2092,7 +2092,7 @@ compile_redir(char_u *line, exarg_T *eap
 						      &t_string, cctx) == FAIL)
 		    return NULL;
 	    }
-	    else if (generate_store_lhs(cctx, lhs, -1) == FAIL)
+	    else if (generate_store_lhs(cctx, lhs, -1, FALSE) == FAIL)
 		return NULL;
 
 	    VIM_CLEAR(lhs->lhs_name);
diff --git a/src/vim9compile.c b/src/vim9compile.c
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1963,6 +1963,7 @@ compile_assignment(char_u *arg, exarg_T 
     {
 	int	instr_count = -1;
 	int	save_lnum;
+	int	skip_store = FALSE;
 
 	if (var_start[0] == '_' && !eval_isnamec(var_start[1]))
 	{
@@ -2186,7 +2187,12 @@ compile_assignment(char_u *arg, exarg_T 
 		    case VAR_VOID:
 		    case VAR_INSTR:
 		    case VAR_SPECIAL:  // cannot happen
-			generate_PUSHNR(cctx, 0);
+			// This is skipped for local variables, they are
+			// always initialized to zero.
+			if (lhs.lhs_dest == dest_local)
+			    skip_store = TRUE;
+			else
+			    generate_PUSHNR(cctx, 0);
 			break;
 		}
 	    }
@@ -2278,7 +2284,8 @@ compile_assignment(char_u *arg, exarg_T 
 		// type of "val" is used.
 		generate_SETTYPE(cctx, lhs.lhs_type);
 
-	    if (generate_store_lhs(cctx, &lhs, instr_count) == FAIL)
+	    if (!skip_store && generate_store_lhs(cctx, &lhs,
+						 instr_count, is_decl) == FAIL)
 	    {
 		cctx->ctx_lnum = save_lnum;
 		goto theend;
diff --git a/src/vim9execute.c b/src/vim9execute.c
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -397,7 +397,12 @@ call_dfunc(
 
     // Initialize local variables
     for (idx = 0; idx < dfunc->df_varcount; ++idx)
-	STACK_TV_BOT(STACK_FRAME_SIZE + idx)->v_type = VAR_UNKNOWN;
+    {
+	typval_T *tv = STACK_TV_BOT(STACK_FRAME_SIZE + idx);
+
+	tv->v_type = VAR_NUMBER;
+	tv->vval.v_number = 0;
+    }
     if (dfunc->df_has_closure)
     {
 	typval_T *tv = STACK_TV_BOT(STACK_FRAME_SIZE + dfunc->df_varcount);
@@ -5002,8 +5007,13 @@ call_def_function(
 	dfunc_T	*dfunc = ((dfunc_T *)def_functions.ga_data)
 							 + ufunc->uf_dfunc_idx;
 
+	// Initialize variables to zero.  That avoids having to generate
+	// initializing instructions for "var nr: number", "var x: any", etc.
 	for (idx = 0; idx < dfunc->df_varcount; ++idx)
-	    STACK_TV_VAR(idx)->v_type = VAR_UNKNOWN;
+	{
+	    STACK_TV_VAR(idx)->v_type = VAR_NUMBER;
+	    STACK_TV_VAR(idx)->vval.v_number = 0;
+	}
 	ectx.ec_stack.ga_len += dfunc->df_varcount;
 	if (dfunc->df_has_closure)
 	{
diff --git a/src/vim9instr.c b/src/vim9instr.c
--- a/src/vim9instr.c
+++ b/src/vim9instr.c
@@ -1886,7 +1886,7 @@ generate_store_var(
 }
 
     int
-generate_store_lhs(cctx_T *cctx, lhs_T *lhs, int instr_count)
+generate_store_lhs(cctx_T *cctx, lhs_T *lhs, int instr_count, int is_decl)
 {
     if (lhs->lhs_dest != dest_local)
 	return generate_store_var(cctx, lhs->lhs_dest,
@@ -1899,8 +1899,9 @@ generate_store_lhs(cctx_T *cctx, lhs_T *
 	garray_T	*instr = &cctx->ctx_instr;
 	isn_T		*isn = ((isn_T *)instr->ga_data) + instr->ga_len - 1;
 
-	// optimization: turn "var = 123" from ISN_PUSHNR + ISN_STORE into
-	// ISN_STORENR
+	// Optimization: turn "var = 123" from ISN_PUSHNR + ISN_STORE into
+	// ISN_STORENR.
+	// And "var = 0" does not need any instruction.
 	if (lhs->lhs_lvar->lv_from_outer == 0
 		&& instr->ga_len == instr_count + 1
 		&& isn->isn_type == ISN_PUSHNR)
@@ -1908,9 +1909,16 @@ generate_store_lhs(cctx_T *cctx, lhs_T *
 	    varnumber_T val = isn->isn_arg.number;
 	    garray_T    *stack = &cctx->ctx_type_stack;
 
-	    isn->isn_type = ISN_STORENR;
-	    isn->isn_arg.storenr.stnr_idx = lhs->lhs_lvar->lv_idx;
-	    isn->isn_arg.storenr.stnr_val = val;
+	    if (val == 0 && is_decl)
+	    {
+		--instr->ga_len;
+	    }
+	    else
+	    {
+		isn->isn_type = ISN_STORENR;
+		isn->isn_arg.storenr.stnr_idx = lhs->lhs_lvar->lv_idx;
+		isn->isn_arg.storenr.stnr_val = val;
+	    }
 	    if (stack->ga_len > 0)
 		--stack->ga_len;
 	}