[PATCH 11/16] cmp: simplify zext(x) cmp C --> x cmp C

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

When doing a compare of a zero-extended value against a constant,
this extension can be dropped and the comparison done on the
original type if the constant is within the original range and
signed compares become the corresponding unsigned one.

Simplify away these sign-extensions.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 simplify.c                        | 11 +++++++++++
 validation/optim/cmp-zext-uimm1.c |  1 -
 validation/optim/cmp-zext.c       |  1 -
 validation/optim/zext-cmpu.c      |  1 -
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/simplify.c b/simplify.c
index eb2c724f6307..1cb5275b7a73 100644
--- a/simplify.c
+++ b/simplify.c
@@ -1149,6 +1149,17 @@ static int simplify_compare_constant(struct instruction *insn, long long value)
 			return replace_pseudo(insn, &insn->src1, def->src);
 		}
 		break;
+	case OP_ZEXT:
+		osize = def->orig_type->bit_size;
+		bits = bits_mask(osize);
+		if (value <= bits) {
+			const struct opcode_table *op = &opcode_table[insn->opcode];
+			if (op->flags & OPF_SIGNED)
+				insn->opcode = op->sign;
+			insn->itype = def->orig_type;
+			return replace_pseudo(insn, &insn->src1, def->src);
+		}
+		break;
 	}
 	return changed;
 }
diff --git a/validation/optim/cmp-zext-uimm1.c b/validation/optim/cmp-zext-uimm1.c
index ffcdaad5c1bd..c21780ea728d 100644
--- a/validation/optim/cmp-zext-uimm1.c
+++ b/validation/optim/cmp-zext-uimm1.c
@@ -9,7 +9,6 @@ int zext_gt_p(unsigned int x) { return (zext(x) >  (BITS    )) == 0; }
 /*
  * check-name: cmp-zext-uimm1
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1
diff --git a/validation/optim/cmp-zext.c b/validation/optim/cmp-zext.c
index ecee6b5e9101..ac4847806251 100644
--- a/validation/optim/cmp-zext.c
+++ b/validation/optim/cmp-zext.c
@@ -11,7 +11,6 @@ _Bool cmpu_zext(ARGS(UINT32)) { return TEST(UINT64, UINT32, a, < , 0xffffffff);
 /*
  * check-name: cmp-zext
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1
diff --git a/validation/optim/zext-cmpu.c b/validation/optim/zext-cmpu.c
index 279ed70e0fda..9758e0710d7b 100644
--- a/validation/optim/zext-cmpu.c
+++ b/validation/optim/zext-cmpu.c
@@ -10,7 +10,6 @@ int gtl(unsigned x) { return (((long long)x) >  0x0fffffffeULL) == (x >  0xfffff
 /*
  * check-name: zext-cmpu
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1
-- 
2.29.2