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| author | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2020-10-06 21:29:32 +0200 |
|---|---|---|
| committer | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2020-11-22 15:58:07 +0100 |
| commit | a49663abcf7f1a0139b403fa23856ca998ffee28 (patch) | |
| tree | a95154341a0aed194ea7cec82fd8306d3e5ad50d /simplify.c | |
| parent | 8b1d40e3721f82b57bad55d9095d7ec7db5bbbef (diff) | |
| download | sparse-dev-a49663abcf7f1a0139b403fa23856ca998ffee28.tar.gz | |
not: simplify (~x {&,|,^} x) --> {0,~0,~0}
Simplify bitwise operations on a pseudo and its complement
into 0 (for &) or ~0 for (| and ^).
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Diffstat (limited to 'simplify.c')
| -rw-r--r-- | simplify.c | 66 |
1 files changed, 63 insertions, 3 deletions
@@ -1630,6 +1630,66 @@ static int simplify_compare(struct instruction *insn) return 0; } +static int simplify_and_one_side(struct instruction *insn, pseudo_t *p1, pseudo_t *p2) +{ + struct instruction *def; + pseudo_t src1 = *p1; + + switch (DEF_OPCODE(def, src1)) { + case OP_NOT: + if (def->src == *p2) + return replace_with_value(insn, 0); + break; + } + return 0; +} + +static int simplify_and(struct instruction *insn) +{ + return simplify_and_one_side(insn, &insn->src1, &insn->src2) || + simplify_and_one_side(insn, &insn->src2, &insn->src1); +} + +static int simplify_ior_one_side(struct instruction *insn, pseudo_t *p1, pseudo_t *p2) +{ + struct instruction *def; + pseudo_t src1 = *p1; + + switch (DEF_OPCODE(def, src1)) { + case OP_NOT: + if (def->src == *p2) + return replace_with_value(insn, bits_mask(insn->size)); + break; + } + return 0; +} + +static int simplify_ior(struct instruction *insn) +{ + return simplify_ior_one_side(insn, &insn->src1, &insn->src2) || + simplify_ior_one_side(insn, &insn->src2, &insn->src1); +} + +static int simplify_xor_one_side(struct instruction *insn, pseudo_t *p1, pseudo_t *p2) +{ + struct instruction *def; + pseudo_t src1 = *p1; + + switch (DEF_OPCODE(def, src1)) { + case OP_NOT: + if (def->src == *p2) + return replace_with_value(insn, bits_mask(insn->size)); + break; + } + return 0; +} + +static int simplify_xor(struct instruction *insn) +{ + return simplify_xor_one_side(insn, &insn->src1, &insn->src2) || + simplify_xor_one_side(insn, &insn->src2, &insn->src1); +} + static int simplify_constant_unop(struct instruction *insn) { long long val = insn->src1->value; @@ -2162,10 +2222,10 @@ int simplify_instruction(struct instruction *insn) switch (insn->opcode) { case OP_ADD: return simplify_add(insn); case OP_SUB: return simplify_sub(insn); + case OP_AND: return simplify_and(insn); + case OP_OR: return simplify_ior(insn); + case OP_XOR: return simplify_xor(insn); case OP_MUL: - case OP_AND: - case OP_OR: - case OP_XOR: case OP_SHL: case OP_LSR: case OP_ASR: |