diff mbox series

[SPARSE,4/4] simplify AND(x >= 0, x < C) --> (unsigned)x < C

Message ID 20210418153233.45234-5-luc.vanoostenryck@gmail.com (mailing list archive)
State Mainlined, archived
Headers show
Series fix/improve canonicalization of signed compares | expand

Commit Message

Luc Van Oostenryck April 18, 2021, 3:32 p.m. UTC 
Such compares with a signed value are relatively common and can be
easily be simplified into a single unsigned compare. So, do it.

Note: This simplification triggers only 27 times in a x86-64 defconfig
      kernel. I expected more but I suppose it's because most checks
      aren't done against a constant or are done with unsigned values.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 simplify.c                      | 11 +++++++++++
 validation/optim/range-check1.c |  1 -
 validation/optim/range-check2.c |  1 -
 3 files changed, 11 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/simplify.c b/simplify.c
index e0e4f9ebcba9..0a29db189b55 100644
--- a/simplify.c
+++ b/simplify.c
@@ -1920,6 +1920,17 @@  static int simplify_and_one_side(struct instruction *insn, pseudo_t *p1, pseudo_
 			if (def->src1 == defr->src1 && def->src2 == defr->src2)
 				return replace_with_value(insn, 0);
 		}
+		if (def->opcode == OP_SET_GE && is_zero(def->src2)) {
+			switch (DEF_OPCODE(defr, *p2)) {
+			case OP_SET_LE:
+				if (!is_positive(defr->src2, defr->itype->bit_size))
+					break;
+				// (x >= 0) && (x <= C) --> (x u<= C)
+				insn->itype = defr->itype;
+				replace_binop(insn, OP_SET_BE, &insn->src1, defr->src1, &insn->src2, defr->src2);
+				return REPEAT_CSE;
+			}
+		}
 		break;
 	case OP_OR:
 		if (DEF_OPCODE(defr, *p2) == OP_OR) {
diff --git a/validation/optim/range-check1.c b/validation/optim/range-check1.c
index 82b939917da4..358da045c456 100644
--- a/validation/optim/range-check1.c
+++ b/validation/optim/range-check1.c
@@ -8,7 +8,6 @@  _Bool check_ok(long i)
 /*
  * check-name: range-check1
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-contains: setbe\\..*0x3ff
diff --git a/validation/optim/range-check2.c b/validation/optim/range-check2.c
index f565b84ea9db..69c01b9d36d5 100644
--- a/validation/optim/range-check2.c
+++ b/validation/optim/range-check2.c
@@ -8,7 +8,6 @@  _Bool check_ok(int i)
 /*
  * check-name: range-check2
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1