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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.
This commit is contained in:
Neil Schemenauer 2009-10-14 17:17:14 +00:00
parent 647e9d2652
commit 7fdd1cb583
2 changed files with 26 additions and 13 deletions
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4
Misc/NEWS
View File

@ -12,6 +12,10 @@ What's New in Python 2.7 alpha 1
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.

35
Python/compile.c
View File

@ -692,13 +692,13 @@ opcode_stack_effect(int opcode, int oparg)
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 @@ opcode_stack_effect(int opcode, int oparg)
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 @@ opcode_stack_effect(int opcode, int oparg)
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 @@ opcode_stack_effect(int opcode, int oparg)
case COMPARE_OP:
return -1;
case IMPORT_NAME:
return 0;
return -1;
case IMPORT_FROM:
return 1;
@ -835,10 +836,9 @@ opcode_stack_effect(int opcode, int oparg)
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 @@ opcode_stack_effect(int opcode, int oparg)
return -1;
case MAKE_CLOSURE:
return -oparg;
return -oparg-1;
case LOAD_CLOSURE:
return 1;
case LOAD_DEREF:
@ -3328,7 +3328,7 @@ dfs(struct compiler *c, basicblock *b, struct assembler *a)
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 @@ stackdepth_walk(struct compiler *c, basicblock *b, int depth, int maxdepth)
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 */