Remove the tail recursion optimization.

paulsc96 · Mar 26, 2018 · e32b1e2 · e32b1e2
1 parent 9b03de3
commit e32b1e2
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Showing 11 changed files with 347 additions and 378 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,18 @@
+2018-03-26         Arnold D. Robbins     <[email protected]>
+
+	Remove the tail recursion optimization. It's fundamentally
+	broken, in the case where a local var becomes a parameter.
+	Thanks to Denis Shirokov <[email protected]> for the report.
+	See test/tailrecurse.awk.
+
+	* awk.h [num_tail_calls, tail_call]: Remove definitions.
+	* awkgram.y (grammar, mk_function): Remove code related to
+	the tail recursion optimization.
+	* eval.c (dump_fcall_stack): Adjust dumping code since no longer
+	looping through tail call recursion.
+	(setup_frame): Remove code related to the tail recursion optimization.
+	(init_interpret): Ditto.
+
 2018-03-22         Arnold D. Robbins     <[email protected]>
 
 	* configure.ac: Check for %a support in system printf.

diff --git a/awk.h b/awk.h
@@ -527,7 +527,6 @@ typedef struct exp_node {
 #define func_node    sub.nodep.x.extra
 #define prev_frame_size	sub.nodep.reflags
 #define reti         sub.nodep.l.li
-#define num_tail_calls    sub.nodep.cnt
 
 /* Node_var: */
 #define var_value    lnode
@@ -862,9 +861,6 @@ typedef struct exp_instruction {
 /* Op_func_call, Op_func */
 #define func_body       x.xn
 
-/* Op_func_call */
-#define tail_call	d.dl
-
 /* Op_subscript */
 #define sub_count       d.dl