diff options
Diffstat (limited to 'simplify.c')
| -rw-r--r-- | simplify.c | 92 |
1 files changed, 85 insertions, 7 deletions
@@ -575,12 +575,26 @@ static long long check_shift_count(struct instruction *insn, unsigned long long return sval; } +static int simplify_or_lsr(struct instruction *insn, pseudo_t src, pseudo_t other, unsigned shift) +{ + // src->def->opcode == OP_AND + pseudo_t src2 = src->def->src2; + + if (!constant(src2)) + return 0; + if (((unsigned long long) src2->value) >> shift) + return 0; + return replace_pseudo(insn, &insn->src1, other); +} + static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long value) { struct instruction *def; + unsigned long long mask; unsigned long long nval; unsigned int size; pseudo_t src2; + pseudo_t src; if (!value) return replace_with_pseudo(insn, pseudo); @@ -627,14 +641,54 @@ static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long v break; case OP_LSR: size = operand_size(insn, pseudo); - /* fall through */ - case OP_SHL: if (value >= size) goto zero; - if (pseudo->type != PSEUDO_REG) + switch(DEF_OPCODE(def, pseudo)) { + case OP_AND: + // replace (A & M) >> S + // by (A >> S) & (M >> S) + if (!constant(def->src2)) + break; + if (nbr_users(pseudo) > 1) + break; + mask = def->src2->value; + def->opcode = OP_LSR; + def->src2 = insn->src2; + insn->opcode = OP_AND; + insn->src2 = value_pseudo(mask >> value); + return REPEAT_CSE; + case OP_LSR: + goto case_shift_shift; + case OP_OR: + // replace ((A & M) | B) >> S + // by (B >> S) + // when (M >> S) == 0 + src = def->src1; + if (def_opcode(src) == OP_AND) + return simplify_or_lsr(insn, src, def->src2, value); + src = def->src2; + if (def_opcode(src) == OP_AND) + return simplify_or_lsr(insn, src, def->src1, value); break; - def = pseudo->def; - if (def->opcode == insn->opcode) { + case OP_SHL: + // replace (A << S) >> S + // by A & (Mask(size) >> S) + if (!constant(def->src2)) + break; + if (def->src2->value != value) + break; + size = insn->size - value; + insn->opcode = OP_AND; + insn->src2 = value_pseudo((1ULL << size) - 1); + return replace_pseudo(insn, &insn->src1, def->src1); + } + break; + case OP_SHL: + if (value >= size) + goto zero; + switch(DEF_OPCODE(def, pseudo)) { + case OP_SHL: + case_shift_shift: // also for LSR - LSR if (def == insn) // cyclic DAG! break; src2 = def->src2; @@ -770,18 +824,41 @@ static int simplify_seteq_setne(struct instruction *insn, long long value) return 0; } +static int simplify_and_or_mask(struct instruction *insn, pseudo_t and, pseudo_t other, unsigned long long mask) +{ + struct instruction *def = and->def; + + if (!constant(def->src2)) + return 0; + if (def->src2->value & mask) + return 0; + return replace_pseudo(insn, &insn->src1, other); +} + static int simplify_constant_mask(struct instruction *insn, unsigned long long mask) { pseudo_t old = insn->src1; unsigned long long omask; unsigned long long nmask; struct instruction *def; + pseudo_t src1, src2; int osize; switch (DEF_OPCODE(def, old)) { case OP_FPCMP ... OP_BINCMP_END: osize = 1; goto oldsize; + case OP_OR: + // Let's handle ((A & M') | B ) & M + // or (B | (A & M')) & M + // when M' & M == 0 + src1 = def->src1; + src2 = def->src2; + if (def_opcode(src1) == OP_AND) + return simplify_and_or_mask(insn, src1, src2, mask); + if (def_opcode(src2) == OP_AND) + return simplify_and_or_mask(insn, src2, src1, mask); + break; case OP_ZEXT: osize = def->orig_type->bit_size; /* fall through */ @@ -1091,7 +1168,7 @@ static int simplify_one_memop(struct instruction *insn, pseudo_t orig) offset: /* Invalid code */ - if (new == orig) { + if (new == orig || new == addr) { if (new == VOID) return 0; /* @@ -1103,8 +1180,9 @@ offset: */ if (repeat_phase & REPEAT_CFG_CLEANUP) return 0; - new = VOID; warning(insn->pos, "crazy programmer"); + replace_pseudo(insn, &insn->src, VOID); + return 0; } insn->offset += off->value; replace_pseudo(insn, &insn->src, new); |