Issue #1754094: Improve the stack depth calculation in the compiler.
There should be no other effect than a small decrease in memory use.
Patch by Christopher Tur Lesniewski-Laas.
diff --git a/Misc/NEWS b/Misc/NEWS
index 2fdbd6d..5c5acd7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,10 @@
Core and Builtins
-----------------
+- Issue #1754094: Improve the stack depth calculation in the compiler.
+ There should be no other effect than a small decrease in memory use.
+ Patch by Christopher Tur Lesniewski-Laas.
+
- Issue #7084: Fix a (very unlikely) crash when printing a list from one
thread, and mutating it from another one. Patch by Scott Dial.
diff --git a/Python/compile.c b/Python/compile.c
index 3b5f5ef..844aca6 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -692,13 +692,13 @@
return -1;
case SLICE+0:
- return 1;
+ return 0;
case SLICE+1:
- return 0;
- case SLICE+2:
- return 0;
- case SLICE+3:
return -1;
+ case SLICE+2:
+ return -1;
+ case SLICE+3:
+ return -2;
case STORE_SLICE+0:
return -2;
@@ -778,7 +778,8 @@
case POP_BLOCK:
return 0;
case END_FINALLY:
- return -1; /* or -2 or -3 if exception occurred */
+ return -3; /* or -1 or -2 if no exception occurred or
+ return/break/continue */
case BUILD_CLASS:
return -2;
@@ -789,7 +790,7 @@
case UNPACK_SEQUENCE:
return oparg-1;
case FOR_ITER:
- return 1;
+ return 1; /* or -1, at end of iterator */
case STORE_ATTR:
return -2;
@@ -815,7 +816,7 @@
case COMPARE_OP:
return -1;
case IMPORT_NAME:
- return 0;
+ return -1;
case IMPORT_FROM:
return 1;
@@ -835,10 +836,9 @@
case CONTINUE_LOOP:
return 0;
case SETUP_LOOP:
- return 0;
case SETUP_EXCEPT:
case SETUP_FINALLY:
- return 3; /* actually pushed by an exception */
+ return 0;
case LOAD_FAST:
return 1;
@@ -867,7 +867,7 @@
return -1;
case MAKE_CLOSURE:
- return -oparg;
+ return -oparg-1;
case LOAD_CLOSURE:
return 1;
case LOAD_DEREF:
@@ -3328,7 +3328,7 @@
static int
stackdepth_walk(struct compiler *c, basicblock *b, int depth, int maxdepth)
{
- int i;
+ int i, target_depth;
struct instr *instr;
if (b->b_seen || b->b_startdepth >= depth)
return maxdepth;
@@ -3341,8 +3341,17 @@
maxdepth = depth;
assert(depth >= 0); /* invalid code or bug in stackdepth() */
if (instr->i_jrel || instr->i_jabs) {
+ target_depth = depth;
+ if (instr->i_opcode == FOR_ITER) {
+ target_depth = depth-2;
+ } else if (instr->i_opcode == SETUP_FINALLY ||
+ instr->i_opcode == SETUP_EXCEPT) {
+ target_depth = depth+3;
+ if (target_depth > maxdepth)
+ maxdepth = target_depth;
+ }
maxdepth = stackdepth_walk(c, instr->i_target,
- depth, maxdepth);
+ target_depth, maxdepth);
if (instr->i_opcode == JUMP_ABSOLUTE ||
instr->i_opcode == JUMP_FORWARD) {
goto out; /* remaining code is dead */