210 lines
7.5 KiB
C
210 lines
7.5 KiB
C
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/**
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* @file value_pool.c
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* @brief Tests that creating a name inside a scope costs the value pool nothing.
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*
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* This is the defect a Breakout written against the interpreter died of after
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* twenty-five seconds, and nothing in either corpus could have found it: the
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* pool holds 4096 values, so it takes *thousands* of scope entries to see, and
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* nothing else here runs that long.
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*
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* The cause was that scope exit returns the variable *slot* and not its storage.
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* akbasic_runtime_prev_environment() marks the variable unused,
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* akbasic_runtime_new_variable() memsets the slot it hands back -- clearing
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* `values` -- and akbasic_variable_init() therefore drew fresh slots for a
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* variable whose old ones were still counted. Every GOSUB that created a local
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* leaked, with no diagnostic until the pool ran dry on whichever line happened
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* to be unlucky.
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*
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* A scalar now lives in the variable itself, so the pool is not involved at all.
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* Two of the counts below are past the old 4096 ceiling on purpose -- under it,
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* they would pass against the broken interpreter too. The third takes the
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* opposite approach and asks for the whole pool after only a few scopes, which
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* is cheaper and sharper: one leaked slot and it has nowhere to go.
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*/
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#include <string.h>
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#include <akbasic/error.h>
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#include <akbasic/runtime.h>
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#include "harness.h"
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#include "testutil.h"
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/** @brief Run a program to completion, bounded so a hang fails rather than waits. */
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static akerr_ErrorContext AKERR_NOIGNORE *run_program(const char *source)
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{
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PREPARE_ERROR(errctx);
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PASS(errctx, harness_start(NULL));
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PASS(errctx, akbasic_runtime_load(&HARNESS_RUNTIME, source));
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PASS(errctx, akbasic_runtime_start(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
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PASS(errctx, akbasic_runtime_run(&HARNESS_RUNTIME, 2000000));
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SUCCEED_RETURN(errctx);
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}
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/**
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* @brief 6,000 GOSUBs, each creating a local, cost nothing.
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*
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* TODO.md section 6 item 30's reduction, unchanged. It used to fail at
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* `LOC# = 1` on the 4091st call with "Array of 1 elements does not fit in the
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* 0 remaining value slots" -- naming the line that was unlucky rather than the
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* line that was wrong, which is most of why it cost an evening to find.
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*/
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static void test_scoped_scalar_costs_nothing(void)
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{
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TEST_REQUIRE_OK(run_program("10 X# = 0\n"
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"20 FOR T# = 1 TO 6000\n"
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"30 GOSUB SUBA\n"
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"40 NEXT T#\n"
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"50 PRINT \"OK \" + X#\n"
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"60 END\n"
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"70 LABEL SUBA\n"
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"80 LOC# = 1\n"
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"90 X# = X# + LOC#\n"
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"100 RETURN\n"));
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TEST_REQUIRE_STR(HARNESS_OUTPUT, "OK 6000\n");
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harness_stop();
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}
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/**
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* @brief A `FOR` counter is a name like any other, and costs nothing either.
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*
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