diff mbox series

[07/10] cmps: canonicalize SMIN/SMAX +- 1 --> EQ/NE

Message ID 20210126220432.58265-8-luc.vanoostenryck@gmail.com (mailing list archive)
State Mainlined, archived
Headers show
Series simplify and canonicalize signed compares | expand

Commit Message

Luc Van Oostenryck Jan. 26, 2021, 10:04 p.m. UTC 
Compares with SMIN  + 1 or SMAX - 1 are equivalent to an equality
testing. For example, (x < SMIN + 1) is the same as (x == SMIN).

Canonicalize these to the equality testing since these are usually
simpler to handle.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 simplify.c                               | 8 ++++++++
 validation/optim/canonical-cmpe-minmax.c | 1 -
 2 files changed, 8 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/simplify.c b/simplify.c
index f7c6c68d4ce9..ad3adb11595e 100644
--- a/simplify.c
+++ b/simplify.c
@@ -1175,24 +1175,32 @@  static int simplify_compare_constant(struct instruction *insn, long long value)
 			return replace_with_pseudo(insn, value_pseudo(0));
 		if (value == sign_mask(size))	// (x <  SMAX) --> (x != SMAX)
 			return replace_opcode(insn, OP_SET_NE);
+		if (value == sign_bit(size) + 1)// (x < SMIN + 1) --> (x == SMIN)
+			return replace_binop_value(insn, OP_SET_EQ, sign_bit(size));
 		break;
 	case OP_SET_LE:
 		if (value == sign_mask(size))	// (x <= SMAX) --> 1
 			return replace_with_pseudo(insn, value_pseudo(1));
 		if (value == sign_bit(size))	// (x <= SMIN) --> (x == SMIN)
 			return replace_opcode(insn, OP_SET_EQ);
+		if (value == sign_mask(size) - 1) // (x <= SMAX - 1) --> (x != SMAX)
+			return replace_binop_value(insn, OP_SET_NE, sign_mask(size));
 		break;
 	case OP_SET_GE:
 		if (value == sign_bit(size))	// (x >= SMIN) --> 1
 			return replace_with_pseudo(insn, value_pseudo(1));
 		if (value == sign_mask(size))	// (x >= SMAX) --> (x == SMAX)
 			return replace_opcode(insn, OP_SET_EQ);
+		if (value == sign_bit(size) + 1)// (x >= SMIN + 1) --> (x != SMIN)
+			return replace_binop_value(insn, OP_SET_NE, sign_bit(size));
 		break;
 	case OP_SET_GT:
 		if (value == sign_mask(size))	// (x >  SMAX) --> 0
 			return replace_with_pseudo(insn, value_pseudo(0));
 		if (value == sign_bit(size))	// (x >  SMIN) --> (x != SMIN)
 			return replace_opcode(insn, OP_SET_NE);
+		if (value == sign_mask(size) - 1) // (x > SMAX - 1) --> (x == SMAX)
+			return replace_binop_value(insn, OP_SET_EQ, sign_mask(size));
 		break;
 
 	case OP_SET_B:
diff --git a/validation/optim/canonical-cmpe-minmax.c b/validation/optim/canonical-cmpe-minmax.c
index c72819244b95..32b272435fa2 100644
--- a/validation/optim/canonical-cmpe-minmax.c
+++ b/validation/optim/canonical-cmpe-minmax.c
@@ -10,7 +10,6 @@  int ge_smin(int a) { return (a >= (SMIN + 1)) == (a != SMIN); }
 /*
  * check-name: canonical-cmpe-minmax
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1