822590f5e
Denys Vlasenko
2023-06-17
Subject
shell/math: eliminate some redundant stores on return code path
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shell/math.c+23 -20
| @@ -303,21 +303,21 @@ arith_lookup_val(arith_state_t *math_state, var_or_num_t *t) | |
| static NOINLINE const char* | |
| arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_or_num_t **numstackptr) | |
| { | |
| - | #define NUMPTR (*numstackptr) |
| + | #define NUMSTACKPTR (*numstackptr) |
| var_or_num_t *top_of_stack; | |
| arith_t rez; | |
| /* There is no operator that can work without arguments */ | |
| - | if (NUMPTR == numstack) |
| + | if (NUMSTACKPTR == numstack) |
| goto syntax_err; | |
| - | top_of_stack = NUMPTR - 1; |
| + | top_of_stack = NUMSTACKPTR - 1; |
| if (op == TOK_CONDITIONAL_SEP) { | |
| /* "expr1 ? expr2 : expr3" operation */ | |
| var_or_num_t *expr1 = &top_of_stack[-2]; | |
| - | NUMPTR = expr1 + 1; |
| + | NUMSTACKPTR = expr1 + 1; |
| if (expr1 < numstack) /* Example: $((2:3)) */ | |
| return "malformed ?: operator"; | |
| if (expr1->val != 0) /* select expr2 or expr3 */ | |
| @@ -348,12 +348,17 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| goto syntax_err; /* no */ | |
| /* Pop numstack */ | |
| - | NUMPTR = top_of_stack; /* this decrements NUMPTR */ |
| + | NUMSTACKPTR = top_of_stack; /* this decrements NUMSTACKPTR */ |
| top_of_stack--; /* now points to left side */ | |
| if (math_state->evaluation_disabled) { | |
| dbg("binary op %02x skipped", op); | |
| goto ret_NULL; | |
| + | /* bash 5.2.12 does not execute "2/0" in disabled |
| + | * branches of ?: (and thus does not complain), |
| + | * but complains about negative exp: "2**-1". |
| + | * I don't think we need to emulate that. |
| + | */ |
| } | |
| right_side_val = rez; | |
| @@ -457,7 +462,7 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| return NULL; | |
| syntax_err: | |
| return "arithmetic syntax error"; | |
| - | #undef NUMPTR |
| + | #undef NUMSTACKPTR |
| } | |
| /* longest must be first */ | |
| @@ -630,8 +635,7 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| if (*expr == '\0') { | |
| if (expr == start_expr) { | |
| /* Null expression */ | |
| - | numstack->val = 0; |
| - | goto ret; |
| + | return 0; |
| } | |
| /* This is only reached after all tokens have been extracted from the | |
| @@ -650,9 +654,9 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| /* At this point, we're done with the expression */ | |
| if (numstackptr != numstack + 1) { | |
| /* if there is not exactly one result, it's bad */ | |
| - | goto err; |
| + | goto syntax_err; |
| } | |
| - | goto ret; |
| + | return numstack->val; |
| } | |
| p = endofname(expr); | |
| @@ -697,7 +701,7 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| * a new number or name. Example: 09v09v09v09v09v09v09v09v09v | |
| */ | |
| if (isalnum(*expr) || *expr == '_') | |
| - | goto err; |
| + | goto syntax_err; |
| if (errno) | |
| numstackptr->val = 0; /* bash compat */ | |
| goto push_num; | |
| @@ -750,7 +754,7 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| if (*p == '\0') { | |
| /* No next element, operator not found */ | |
| //math_state->syntax_error_at = expr; | |
| - | goto err; |
| + | goto syntax_err; |
| } | |
| } | |
| /* NB: expr now points past the operator */ | |
| @@ -812,7 +816,7 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| /* binary, ternary or RPAREN */ | |
| if (lasttok != TOK_NUM) { | |
| /* must be preceded by a num */ | |
| - | goto err; |
| + | goto syntax_err; |
| } | |
| /* if op is RPAREN: | |
| * while opstack is not empty: | |
| @@ -883,7 +887,7 @@ dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[ | |
| } /* while (opstack not empty) */ | |
| if (op == TOK_RPAREN) /* unpaired RPAREN? */ | |
| - | goto err; |
| + | goto syntax_err; |
| check_cond: | |
| if (op == TOK_CONDITIONAL) { | |
| /* We just now evaluated EXPR before "?". | |
| @@ -914,20 +918,19 @@ dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[ | |
| } else if (ternary_level == math_state->evaluation_disabled) { | |
| math_state->evaluation_disabled = 0; | |
| dbg("':' entered: evaluation_disabled=CLEAR"); | |
| - | } /* else: ternary_level > nonzero evaluation_disabled: we are in nested ?:, in its disabled branch */ |
| - | /* do nothing */ |
| + | } /* else: ternary_level > evaluation_disabled && evaluation_disabled != 0 */ |
| + | /* We are in nested "?:" while in outer "?:" disabled branch */ |
| + | /* do_nothing */ |
| } | |
| goto tok_found1; | |
| } | |
| } /* while (1) */ | |
| - | err: |
| + | syntax_err: |
| errmsg = "arithmetic syntax error"; | |
| err_with_custom_msg: | |
| - | numstack->val = -1; |
| - | ret: |
| math_state->errmsg = errmsg; | |
| - | return numstack->val; |
| + | return -1; |
| } | |
| arith_t FAST_FUNC | |