From db63af5172f159c5a1983579b081b3bac7f03f0e Mon Sep 17 00:00:00 2001 From: notaz Date: Wed, 18 Mar 2015 04:14:56 +0200 Subject: [PATCH] translate: eliminate some useless func ptr reads --- tools/translate.c | 218 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 190 insertions(+), 28 deletions(-) diff --git a/tools/translate.c b/tools/translate.c index e9ea443..a894f17 100644 --- a/tools/translate.c +++ b/tools/translate.c @@ -2141,6 +2141,10 @@ static void op_set_clear_flag(struct parsed_op *po, || ((ops[_i].flags & (OPF_JMP|OPF_CJMP|OPF_RMD)) == OPF_JMP \ && ops[_i].op != OP_CALL)) +#define check_i(po, i) \ + if ((i) < 0) \ + ferr(po, "bad " #i ": %d\n", i) + static int scan_for_pop(int i, int opcnt, const char *reg, int magic, int depth, int *maxdepth, int do_flags) { @@ -2173,6 +2177,7 @@ static int scan_for_pop(int i, int opcnt, const char *reg, if (po->btj != NULL) { // jumptable for (j = 0; j < po->btj->count; j++) { + check_i(po, po->btj->d[j].bt_i); ret |= scan_for_pop(po->btj->d[j].bt_i, opcnt, reg, magic, depth, maxdepth, do_flags); if (ret < 0) @@ -2181,11 +2186,7 @@ static int scan_for_pop(int i, int opcnt, const char *reg, return ret; } - if (po->bt_i < 0) { - ferr(po, "dead branch\n"); - return -1; - } - + check_i(po, po->bt_i); if (po->flags & OPF_CJMP) { ret |= scan_for_pop(po->bt_i, opcnt, reg, magic, depth, maxdepth, do_flags); @@ -2323,16 +2324,14 @@ static void scan_propagate_df(int i, int opcnt) if (po->flags & OPF_JMP) { if (po->btj != NULL) { // jumptable - for (j = 0; j < po->btj->count; j++) + for (j = 0; j < po->btj->count; j++) { + check_i(po, po->btj->d[j].bt_i); scan_propagate_df(po->btj->d[j].bt_i, opcnt); + } return; } - if (po->bt_i < 0) { - ferr(po, "dead branch\n"); - return; - } - + check_i(po, po->bt_i); if (po->flags & OPF_CJMP) scan_propagate_df(po->bt_i, opcnt); else @@ -2352,13 +2351,57 @@ static void scan_propagate_df(int i, int opcnt) ferr(po, "missing DF clear?\n"); } +// is operand 'opr' referenced by parsed_op 'po'? +static int is_opr_referenced(const struct parsed_opr *opr, + const struct parsed_op *po) +{ + int i, mask; + + if (opr->type == OPT_REG) { + mask = po->regmask_dst | po->regmask_src; + if (po->op == OP_CALL) + mask |= (1 << xAX) | (1 << xCX) | (1 << xDX); + if ((1 << opr->reg) & mask) + return 1; + else + return 0; + } + + for (i = 0; i < po->operand_cnt; i++) + if (IS(po->operand[0].name, opr->name)) + return 1; + + return 0; +} + +// is operand 'opr' read by parsed_op 'po'? +static int is_opr_read(const struct parsed_opr *opr, + const struct parsed_op *po) +{ + int mask; + + if (opr->type == OPT_REG) { + mask = po->regmask_src; + if (po->op == OP_CALL) + // assume worst case + mask |= (1 << xAX) | (1 << xCX) | (1 << xDX); + if ((1 << opr->reg) & mask) + return 1; + else + return 0; + } + + // yes I'm lazy + return 0; +} + // is operand 'opr' modified by parsed_op 'po'? static int is_opr_modified(const struct parsed_opr *opr, const struct parsed_op *po) { int mask; - if ((po->flags & OPF_RMD) || !(po->flags & OPF_DATA)) + if (!(po->flags & OPF_DATA)) return 0; if (opr->type == OPT_REG) { @@ -2441,10 +2484,6 @@ static int scan_for_mod_opr0(struct parsed_op *po_test, return -1; } -#define check_i(po, i) \ - if ((i) < 0) \ - ferr(po, "bad " #i ": %d\n", i) - static int scan_for_flag_set(int i, int magic, int *branched, int *setters, int *setter_cnt) { @@ -2738,7 +2777,8 @@ static const struct parsed_proto *try_recover_pp( } static void scan_for_call_type(int i, const struct parsed_opr *opr, - int magic, const struct parsed_proto **pp_found, int *multi) + int magic, const struct parsed_proto **pp_found, int *pp_i, + int *multi) { const struct parsed_proto *pp = NULL; struct parsed_op *po; @@ -2751,7 +2791,7 @@ static void scan_for_call_type(int i, const struct parsed_opr *opr, lr = &g_label_refs[i]; for (; lr != NULL; lr = lr->next) { check_i(&ops[i], lr->i); - scan_for_call_type(lr->i, opr, magic, pp_found, multi); + scan_for_call_type(lr->i, opr, magic, pp_found, pp_i, multi); } if (i > 0 && LAST_OP(i - 1)) return; @@ -2816,8 +2856,10 @@ static void scan_for_call_type(int i, const struct parsed_opr *opr, } *multi = 1; } - if (pp != NULL) + if (pp != NULL) { *pp_found = pp; + *pp_i = po - ops; + } } // early check for tail call or branch back @@ -3039,12 +3081,13 @@ static void scan_prologue_epilogue(int opcnt) } static const struct parsed_proto *resolve_icall(int i, int opcnt, - int *multi_src) + int *pp_i, int *multi_src) { const struct parsed_proto *pp = NULL; int search_advice = 0; *multi_src = 0; + *pp_i = -1; switch (ops[i].operand[0].type) { case OPT_REGMEM: @@ -3056,7 +3099,7 @@ static const struct parsed_proto *resolve_icall(int i, int opcnt, // fallthrough default: scan_for_call_type(i, &ops[i].operand[0], i + opcnt * 9, &pp, - multi_src); + pp_i, multi_src); break; } @@ -3064,7 +3107,7 @@ static const struct parsed_proto *resolve_icall(int i, int opcnt, } // find an instruction that changed opr before i op -// *op_i must be set to -1 by caller +// *op_i must be set to -1 by the caller // *entry is set to 1 if one source is determined to be the caller // returns 1 if found, *op_i is then set to origin static int resolve_origin(int i, const struct parsed_opr *opr, @@ -3116,6 +3159,110 @@ static int resolve_origin(int i, const struct parsed_opr *opr, } } +// find an instruction that previously referenced opr +// if multiple results are found - fail +// *op_i must be set to -1 by the caller +// returns 1 if found, *op_i is then set to referencer insn +static int resolve_last_ref(int i, const struct parsed_opr *opr, + int magic, int *op_i) +{ + struct label_ref *lr; + int ret = 0; + + if (ops[i].cc_scratch == magic) + return 0; + ops[i].cc_scratch = magic; + + while (1) { + if (g_labels[i] != NULL) { + lr = &g_label_refs[i]; + for (; lr != NULL; lr = lr->next) { + check_i(&ops[i], lr->i); + ret |= resolve_last_ref(lr->i, opr, magic, op_i); + } + if (i > 0 && LAST_OP(i - 1)) + return ret; + } + + i--; + if (i < 0) + return -1; + + if (ops[i].cc_scratch == magic) + return 0; + ops[i].cc_scratch = magic; + + if (!is_opr_referenced(opr, &ops[i])) + continue; + + if (*op_i >= 0) + return -1; + + *op_i = i; + return 1; + } +} + +// find next instruction that reads opr +// if multiple results are found - fail +// *op_i must be set to -1 by the caller +// returns 1 if found, *op_i is then set to referencer insn +static int find_next_read(int i, int opcnt, + const struct parsed_opr *opr, int magic, int *op_i) +{ + struct parsed_op *po; + int j, ret = 0; + + for (; i < opcnt; i++) + { + if (ops[i].cc_scratch == magic) + return 0; + ops[i].cc_scratch = magic; + + po = &ops[i]; + if ((po->flags & OPF_JMP) && po->op != OP_CALL) { + if (po->btj != NULL) { + // jumptable + for (j = 0; j < po->btj->count; j++) { + check_i(po, po->btj->d[j].bt_i); + ret |= find_next_read(po->btj->d[j].bt_i, opcnt, opr, + magic, op_i); + } + return ret; + } + + if (po->flags & OPF_RMD) + continue; + check_i(po, po->bt_i); + if (po->flags & OPF_CJMP) { + ret = find_next_read(po->bt_i, opcnt, opr, magic, op_i); + if (ret < 0) + return ret; + } + + i = po->bt_i - 1; + continue; + } + + if (!is_opr_read(opr, po)) { + if (is_opr_modified(opr, po)) + // it's overwritten + return 0; + if (po->flags & OPF_TAIL) + return 0; + continue; + } + + if (*op_i >= 0) + return -1; + + *op_i = i; + return 1; + } + + return 0; +} + static int try_resolve_const(int i, const struct parsed_opr *opr, int magic, unsigned int *val) { @@ -3173,6 +3320,7 @@ static struct parsed_proto *process_call(int i, int opcnt) const struct parsed_proto *pp_c; struct parsed_proto *pp; const char *tmpname; + int call_i = -1, ref_i = -1; int adj = 0, multipath = 0; int ret, arg; @@ -3181,7 +3329,7 @@ static struct parsed_proto *process_call(int i, int opcnt) if (pp == NULL) { // indirect call - pp_c = resolve_icall(i, opcnt, &multipath); + pp_c = resolve_icall(i, opcnt, &call_i, &multipath); if (pp_c != NULL) { if (!pp_c->is_func && !pp_c->is_fptr) ferr(po, "call to non-func: %s\n", pp_c->name); @@ -3195,6 +3343,23 @@ static struct parsed_proto *process_call(int i, int opcnt) case OPT_REG: // we resolved this call and no longer need the register po->regmask_src &= ~(1 << po->operand[0].reg); + + if (!multipath && i != call_i && ops[call_i].op == OP_MOV + && ops[call_i].operand[1].type == OPT_LABEL) + { + // no other source users? + ret = resolve_last_ref(i, &po->operand[0], opcnt * 10, + &ref_i); + if (ret == 1 && call_i == ref_i) { + // and nothing uses it after us? + ref_i = -1; + ret = find_next_read(i + 1, opcnt, &po->operand[0], + opcnt * 11, &ref_i); + if (ret != 1) + // then also don't need the source mov + ops[call_i].flags |= OPF_RMD; + } + } break; case OPT_REGMEM: pp->is_fptr = 1; @@ -5648,17 +5813,14 @@ static void gen_hdr_dep_pass(int i, int opcnt, unsigned char *cbits, if (po->btj != NULL) { // jumptable for (j = 0; j < po->btj->count; j++) { + check_i(po, po->btj->d[j].bt_i); gen_hdr_dep_pass(po->btj->d[j].bt_i, opcnt, cbits, fp, regmask_save, regmask_dst, regmask_dep, has_ret); } return; } - if (po->bt_i < 0) { - ferr(po, "dead branch\n"); - return; - } - + check_i(po, po->bt_i); if (po->flags & OPF_CJMP) { gen_hdr_dep_pass(po->bt_i, opcnt, cbits, fp, regmask_save, regmask_dst, regmask_dep, has_ret); -- 2.39.5