diff --git a/tools/qfcc/include/expr.h b/tools/qfcc/include/expr.h
index 4d0c41cbc..007ce347a 100644
--- a/tools/qfcc/include/expr.h
+++ b/tools/qfcc/include/expr.h
@@ -905,6 +905,10 @@ expr_t *sizeof_expr (expr_t *expr, struct type_s *type);
 
 expr_t *fold_constants (expr_t *e);
 
+void edag_flush (void);
+expr_t *edag_add_expr (expr_t *e);
+
+
 ///@}
 
 #endif//__expr_h
diff --git a/tools/qfcc/include/shared.h b/tools/qfcc/include/shared.h
index 81b883de9..102f31b44 100644
--- a/tools/qfcc/include/shared.h
+++ b/tools/qfcc/include/shared.h
@@ -37,6 +37,7 @@ extern struct expr_s     *local_expr;
 extern enum vis_e       current_visibility;
 extern enum storage_class_e current_storage;
 extern struct symtab_s *current_symtab;
+extern bool no_flush_dag;
 
 struct symbol_s *check_redefined (struct symbol_s *sym);
 extern struct symbol_s *check_undefined (struct symbol_s *sym);
diff --git a/tools/qfcc/source/Makemodule.am b/tools/qfcc/source/Makemodule.am
index 07f954141..56c6142a2 100644
--- a/tools/qfcc/source/Makemodule.am
+++ b/tools/qfcc/source/Makemodule.am
@@ -32,6 +32,7 @@ qfcc_SOURCES = \
 	tools/qfcc/source/expr_bool.c \
 	tools/qfcc/source/expr_cast.c \
 	tools/qfcc/source/expr_compound.c \
+	tools/qfcc/source/expr_dag.c \
 	tools/qfcc/source/expr_obj.c \
 	tools/qfcc/source/expr_vector.c \
 	tools/qfcc/source/evaluate.c \
diff --git a/tools/qfcc/source/expr.c b/tools/qfcc/source/expr.c
index 4c3dc1f1f..24d234a93 100644
--- a/tools/qfcc/source/expr.c
+++ b/tools/qfcc/source/expr.c
@@ -1398,10 +1398,10 @@ expr_t *
 new_alias_expr (type_t *type, expr_t *expr)
 {
 	if (is_ptr (type) && expr->type == ex_address) {
-		// avoid aliasing a pointer to a pointer (redundant)
-		expr = copy_expr (expr);
-		expr->address.type = type;
-		return expr;
+		auto new = new_address_expr (type, expr->address.lvalue,
+									 expr->address.offset);
+		new->address.type = type;
+		return new;
 	}
 	if (expr->type == ex_alias) {
 		if (expr->alias.offset) {
@@ -1422,7 +1422,7 @@ new_alias_expr (type_t *type, expr_t *expr)
 	alias->alias.expr = expr;
 	alias->file = expr->file;
 	alias->line = expr->line;
-	return alias;
+	return edag_add_expr (alias);
 }
 
 expr_t *
@@ -1444,11 +1444,11 @@ new_offset_alias_expr (type_t *type, expr_t *expr, int offset)
 	expr_t     *alias = new_expr ();
 	alias->type = ex_alias;
 	alias->alias.type = type;
-	alias->alias.expr = expr;
-	alias->alias.offset = new_int_expr (offset);
+	alias->alias.expr = edag_add_expr (expr);
+	alias->alias.offset = edag_add_expr (new_int_expr (offset));
 	alias->file = expr->file;
 	alias->line = expr->line;
-	return alias;
+	return edag_add_expr (alias);
 }
 
 expr_t *
diff --git a/tools/qfcc/source/expr_binary.c b/tools/qfcc/source/expr_binary.c
index b2e9747cf..065e30f62 100644
--- a/tools/qfcc/source/expr_binary.c
+++ b/tools/qfcc/source/expr_binary.c
@@ -1185,7 +1185,7 @@ binary_expr (int op, expr_t *e1, expr_t *e2)
 		int         scalar_op = 0;
 		if (type_width (t1) == 1) {
 			// scalar op vec
-			if (!(e = convert_scalar (e1, op, e2))) {
+			if (!(e = edag_add_expr (convert_scalar (e1, op, e2)))) {
 				return invalid_binary_expr (op, e1, e2);
 			}
 			scalar_op = 1;
@@ -1194,7 +1194,7 @@ binary_expr (int op, expr_t *e1, expr_t *e2)
 		}
 		if (type_width (t2) == 1) {
 			// vec op scalar
-			if (!(e = convert_scalar (e2, op, e1))) {
+			if (!(e = edag_add_expr (convert_scalar (e2, op, e1)))) {
 				return invalid_binary_expr (op, e1, e2);
 			}
 			scalar_op = 1;
@@ -1225,7 +1225,7 @@ binary_expr (int op, expr_t *e1, expr_t *e2)
 				t1 = base_type (t1);
 			}
 			e->expr.type = t1;
-			return e;
+			return edag_add_expr (e);
 		}
 	}
 
@@ -1240,11 +1240,12 @@ binary_expr (int op, expr_t *e1, expr_t *e2)
 	if (expr_type->b_cast)
 		e2 = cast_expr (expr_type->b_cast, e2);
 	if (expr_type->process) {
-		return fold_constants (expr_type->process (op, e1, e2));
+		e = fold_constants (expr_type->process (op, e1, e2));
+		return edag_add_expr (e);
 	}
 
 	if ((e = reimplement_binary_expr (op, e1, e2)))
-		return fold_constants (e);
+		return edag_add_expr (fold_constants (e));
 
 	e = new_binary_expr (op, e1, e2);
 	e->expr.type = expr_type->result_type;
@@ -1253,5 +1254,5 @@ binary_expr (int op, expr_t *e1, expr_t *e2)
 			e->expr.type = &type_float;
 		}
 	}
-	return fold_constants (e);
+	return edag_add_expr (fold_constants (e));
 }
diff --git a/tools/qfcc/source/expr_bool.c b/tools/qfcc/source/expr_bool.c
index 910430e88..989634f3b 100644
--- a/tools/qfcc/source/expr_bool.c
+++ b/tools/qfcc/source/expr_bool.c
@@ -325,5 +325,5 @@ convert_bool (expr_t *e, int block)
 		append_expr (block, e->boolean.e);
 		e->boolean.e = block;
 	}
-	return e;
+	return edag_add_expr (e);
 }
diff --git a/tools/qfcc/source/expr_dag.c b/tools/qfcc/source/expr_dag.c
new file mode 100644
index 000000000..d726fccb2
--- /dev/null
+++ b/tools/qfcc/source/expr_dag.c
@@ -0,0 +1,182 @@
+/*
+	expr_dag.c
+
+	Expression dag support code
+
+	Copyright (C) 2023 Bill Currie <bill@taniwha.org>
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <ctype.h>
+#include <string.h>
+
+#include "QF/darray.h"
+#include "QF/dstring.h"
+#include "QF/va.h"
+
+#include "tools/qfcc/include/diagnostic.h"
+#include "tools/qfcc/include/expr.h"
+#include "tools/qfcc/include/symtab.h"
+#include "tools/qfcc/include/type.h"
+
+typedef struct DARRAY_TYPE (expr_t *) exprset_t;
+
+static exprset_t expr_dag = DARRAY_STATIC_INIT(32);
+
+void
+edag_flush (void)
+{
+	expr_dag.size = 0;
+}
+
+expr_t *
+edag_add_expr (expr_t *expr)
+{
+	if (!expr) {
+		return expr;
+	}
+	for (size_t i = 0; i < expr_dag.size; i++) {
+		expr_t     *e = expr_dag.a[i];
+		if (e->type != expr->type) {
+			continue;
+		}
+		switch (expr->type) {
+			case ex_count:
+				internal_error (expr, "invalid expression type");
+			case ex_label:
+			case ex_labelref:
+			case ex_error:
+			case ex_state:
+			case ex_bool:
+			case ex_compound:
+			case ex_memset:
+			case ex_branch:
+			case ex_return:
+			case ex_adjstk:
+			case ex_with:
+			case ex_args:
+				// these are never put in the dag
+				return expr;
+			case ex_list:
+			case ex_block:
+				if (has_function_call (expr)) {
+					// FIXME const functions can be dagged (and pure if known to be safe)
+					return expr;
+				}
+				return expr;	//FIXME
+			case ex_expr:
+				if (e->expr.type == expr->expr.type
+					&& e->expr.op == expr->expr.op
+					&& e->expr.e1 == expr->expr.e1
+					&& e->expr.e2 == expr->expr.e2) {
+					return e;
+				}
+				break;
+			case ex_uexpr:
+				if (e->expr.type == expr->expr.type
+					&& e->expr.op == expr->expr.op
+					&& e->expr.e1 == expr->expr.e1) {
+					return e;
+				}
+				break;
+			case ex_def:
+				if (e->def == expr->def) {
+					return e;
+				}
+				break;
+			case ex_symbol:
+				if (e->symbol == expr->symbol) {
+					return e;
+				}
+				break;
+			case ex_temp:
+				return expr; //FIXME
+			case ex_vector:
+				return expr; //FIXME
+			case ex_selector:
+				if (e->selector.sel_ref == expr->selector.sel_ref
+					&& e->selector.sel == expr->selector.sel) {
+					return e;
+				}
+				break;
+			case ex_nil:
+				if (e->nil == expr->nil) {
+					return e;
+				}
+				break;
+			case ex_value:
+				if (e->value == expr->value) {
+					return e;
+				}
+				break;
+			case ex_alias:
+				if (e->alias.type == expr->alias.type
+					&& e->alias.expr == expr->alias.expr
+					&& e->alias.offset == expr->alias.offset) {
+					return e;
+				}
+				break;
+			case ex_address:
+				if (e->address.type == expr->address.type
+					&& e->address.lvalue == expr->address.lvalue
+					&& e->address.offset == expr->address.offset) {
+					return e;
+				}
+				break;
+			case ex_assign:
+				return expr;	// FIXME?
+			case ex_horizontal:
+				if (e->hop.type == expr->hop.type
+					&& e->hop.vec == expr->hop.vec
+					&& e->hop.op == expr->hop.op) {
+					return e;
+				}
+				break;
+			case ex_swizzle:
+				if (e->swizzle.type == expr->swizzle.type
+					&& e->swizzle.src == expr->swizzle.src
+					&& e->swizzle.source[0] == expr->swizzle.source[0]
+					&& e->swizzle.source[1] == expr->swizzle.source[1]
+					&& e->swizzle.source[2] == expr->swizzle.source[2]
+					&& e->swizzle.source[3] == expr->swizzle.source[3]
+					&& e->swizzle.neg == expr->swizzle.neg
+					&& e->swizzle.zero == expr->swizzle.zero) {
+					return e;
+				}
+				break;
+			case ex_extend:
+				if (e->extend.type == expr->extend.type
+					&& e->extend.src == expr->extend.src
+					&& e->extend.extend == expr->extend.extend
+					&& e->extend.reverse == expr->extend.reverse) {
+					return e;
+				}
+				break;
+			case ex_multivec:
+				return expr;	//FIXME ?
+		}
+	}
+	DARRAY_APPEND (&expr_dag, expr);
+	return expr;
+}
diff --git a/tools/qfcc/source/qc-parse.y b/tools/qfcc/source/qc-parse.y
index 86c399027..9a5673f6c 100644
--- a/tools/qfcc/source/qc-parse.y
+++ b/tools/qfcc/source/qc-parse.y
@@ -1370,12 +1370,12 @@ array_decl
 	;
 
 decl
-	: declspecs_ts local_expr initdecls ';'
+	: declspecs_ts local_expr initdecls seq_semi
 		{
 			$$ = local_expr;
 			local_expr = 0;
 		}
-	| declspecs_nots local_expr notype_initdecls ';'
+	| declspecs_nots local_expr notype_initdecls seq_semi
 		{
 			$$ = local_expr;
 			local_expr = 0;
@@ -1487,8 +1487,21 @@ pop_scope
 		}
 	;
 
+flush_dag
+	: /* empty */
+		{
+			if (!no_flush_dag) {
+				edag_flush ();
+			}
+		}
+	;
+
+seq_semi
+	: ';' flush_dag
+	;
+
 compound_statement
-	: '{' push_scope statements '}' pop_scope { $$ = $3; }
+	: '{' push_scope flush_dag statements '}' pop_scope flush_dag { $$ = $4; }
 	;
 
 statements
@@ -1496,9 +1509,9 @@ statements
 		{
 			$$ = new_block_expr ();
 		}
-	| statements statement
+	| statements flush_dag statement
 		{
-			$$ = append_expr ($1, $2);
+			$$ = append_expr ($1, $3);
 		}
 	;
 
@@ -1543,7 +1556,7 @@ statement
 		{
 			$$ = case_label_expr (switch_block, 0);
 		}
-	| SWITCH break_label '(' expr switch_block ')' compound_statement
+	| SWITCH break_label '(' comma_expr switch_block ')' compound_statement
 		{
 			$$ = switch_expr (switch_block, break_label, $7);
 			switch_block = $5;
@@ -1554,28 +1567,28 @@ statement
 			expr_t     *label = named_label_expr ($2);
 			$$ = goto_expr (label);
 		}
-	| IF not '(' texpr ')' statement %prec IFX
+	| IF not '(' texpr ')' flush_dag statement %prec IFX
 		{
-			$$ = build_if_statement ($2, $4, $6, 0, 0);
+			$$ = build_if_statement ($2, $4, $7, 0, 0);
 		}
-	| IF not '(' texpr ')' statement else statement
+	| IF not '(' texpr ')' flush_dag statement else statement
 		{
-			$$ = build_if_statement ($2, $4, $6, $7, $8);
+			$$ = build_if_statement ($2, $4, $7, $8, $9);
 		}
 	| FOR push_scope break_label continue_label
-			'(' opt_init_semi opt_expr ';' opt_expr ')' statement pop_scope
+			'(' opt_init_semi opt_expr seq_semi opt_expr ')' flush_dag statement pop_scope
 		{
 			if ($6) {
 				$6 = build_block_expr ($6, false);
 			}
-			$$ = build_for_statement ($6, $7, $9, $11,
+			$$ = build_for_statement ($6, $7, $9, $12,
 									  break_label, continue_label);
 			break_label = $3;
 			continue_label = $4;
 		}
-	| WHILE break_label continue_label not '(' texpr ')' statement
+	| WHILE break_label continue_label not '(' texpr ')' flush_dag statement
 		{
-			$$ = build_while_statement ($4, $6, $8, break_label,
+			$$ = build_while_statement ($4, $6, $9, break_label,
 										continue_label);
 			break_label = $2;
 			continue_label = $3;
@@ -1629,7 +1642,7 @@ not
 	;
 
 else
-	: ELSE
+	: ELSE flush_dag
 		{
 			// this is only to get the the file and line number info
 			$$ = new_nil_expr ();
@@ -1673,7 +1686,7 @@ switch_block
 	;
 
 opt_init_semi
-	: comma_expr ';'
+	: comma_expr seq_semi
 	| decl /* contains ; */
 	| ';'
 		{
@@ -1726,9 +1739,10 @@ ident_expr
 	;
 
 vector_expr
-	: '[' expr ',' expr_list ']'
+	: '[' expr ',' { no_flush_dag = true; } expr_list ']'
 		{
-			$$ = list_prepend_expr ($4, $2);
+			$$ = list_prepend_expr ($5, $2);
+			no_flush_dag = false;
 		}
 	;
 
@@ -1745,9 +1759,9 @@ expr
 	| expr '=' expr				{ $$ = assign_expr ($1, $3); }
 	| expr '=' compound_init	{ $$ = assign_expr ($1, $3); }
 	| expr ASX expr				{ $$ = asx_expr ($2, $1, $3); }
-	| expr '?' expr ':' expr 	{ $$ = conditional_expr ($1, $3, $5); }
-	| expr AND bool_label expr	{ $$ = bool_expr (AND, $3, $1, $4); }
-	| expr OR bool_label expr	{ $$ = bool_expr (OR,  $3, $1, $4); }
+	| expr '?' flush_dag expr ':' expr 	{ $$ = conditional_expr ($1, $4, $6); }
+	| expr AND flush_dag bool_label expr{ $$ = bool_expr (AND, $4, $1, $5); }
+	| expr OR flush_dag bool_label expr	{ $$ = bool_expr (OR,  $4, $1, $5); }
 	| expr EQ expr				{ $$ = binary_expr (EQ,  $1, $3); }
 	| expr NE expr				{ $$ = binary_expr (NE,  $1, $3); }
 	| expr LE expr				{ $$ = binary_expr (LE,  $1, $3); }
@@ -1789,8 +1803,8 @@ comma_expr
 	;
 
 expr_list
-	: expr						{ $$ = new_list_expr ($1); }
-	| expr_list ',' expr		{ $$ = list_append_expr ($1, $3); }
+	: expr							{ $$ = new_list_expr ($1); }
+	| expr_list ',' flush_dag expr	{ $$ = list_append_expr ($1, $4); }
 	;
 
 opt_arg_list
diff --git a/tools/qfcc/source/shared.c b/tools/qfcc/source/shared.c
index acdbf149f..439abdd75 100644
--- a/tools/qfcc/source/shared.c
+++ b/tools/qfcc/source/shared.c
@@ -46,6 +46,7 @@ expr_t     *local_expr;
 vis_t       current_visibility;
 storage_class_t current_storage = sc_global;
 symtab_t   *current_symtab;
+bool        no_flush_dag;
 
 /*	When defining a new symbol, already existing symbols must be in a
 	different scope. However, when they are in a different scope, we want a