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Issue #1754094: Improve the stack depth calculation in the compiler.

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There should be no other effect than a small decrease in memory use.
This commit is contained in:
Neil Schemenauer 2009-10-14 19:14:38 +00:00
parent 46afef330f
commit e441cb71c7
2 changed files with 17 additions and 4 deletions
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17
Python/compile.c
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@ -772,7 +772,7 @@ opcode_stack_effect(int opcode, int oparg)
case UNPACK_EX:
return (oparg&0xFF) + (oparg>>8);
case FOR_ITER:
return 1;
return 1; /* or -1, at end of iterator */
case STORE_ATTR:
return -2;
@ -799,7 +799,7 @@ opcode_stack_effect(int opcode, int oparg)
case COMPARE_OP:
return -1;
case IMPORT_NAME:
return 0;
return -1;
case IMPORT_FROM:
return 1;
@ -3546,7 +3546,7 @@ 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;
@ -3559,8 +3559,17 @@ 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 */