diff mbox series

[6/7] not: simplify (~x {&,|,^} x) --> {0,~0,~0}

Message ID 20201122152731.10994-7-luc.vanoostenryck@gmail.com (mailing list archive)
State Mainlined, archived
Headers show
Series simplify logical negation | expand

Commit Message

Luc Van Oostenryck Nov. 22, 2020, 3:27 p.m. UTC 
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>
---
 simplify.c                   | 66 ++++++++++++++++++++++++++++++++++--
 validation/optim/cse-not01.c |  1 -
 2 files changed, 63 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/simplify.c b/simplify.c
index 203472972bca..b41c155735d1 100644
--- a/simplify.c
+++ b/simplify.c
@@ -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:
diff --git a/validation/optim/cse-not01.c b/validation/optim/cse-not01.c
index f87123f14f13..ea1bb7cf25d4 100644
--- a/validation/optim/cse-not01.c
+++ b/validation/optim/cse-not01.c
@@ -5,7 +5,6 @@  int xor(int a) { return (~a ^ a) == ~0; }
 /*
  * check-name: cse-not01
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1