[Cranelift] folds comparison over bitwise-not operands (#11638)

* [Cranelift] add opts and tests

* [Cranelift] add opts and tests

* [ISLE] add runtests

Author: bongjunj

cranelift/codegen/src/opts/icmp.isle

@@ -298,3 +298,7 @@
 ;; (x < y) ? x : y != x == x > y, for both signed and unsigned.
 (rule (simplify (ne cty (select ty (slt cty x y) x y) x)) (sgt cty x y))
 (rule (simplify (ne cty (select ty (ult cty x y) x y) x)) (ugt cty x y))
+
+(rule (simplify (ult cty (bnot ty x) (bnot ty y))) (ugt cty x y))
+(rule (simplify (slt cty (bnot ty x) (bnot ty y))) (sgt cty x y))
+

cranelift/filetests/filetests/egraph/icmp-new.clif

@@ -0,0 +1,32 @@
+test optimize precise-output
+set opt_level=speed
+target x86_64
+
+function %test1(i8, i8) -> i8 {
+block0(v0: i8, v2: i8):
+    v1 = bnot v0
+    v3 = bnot v2
+    v4 = icmp ult v1, v3
+    return v4
+}
+
+; function %test1(i8, i8) -> i8 fast {
+; block0(v0: i8, v2: i8):
+;     v5 = icmp ugt v0, v2
+;     return v5
+; }
+
+function %test1(i8, i8) -> i8 {
+block0(v0: i8, v2: i8):
+    v1 = bnot v0
+    v3 = bnot v2
+    v4 = icmp slt v1, v3
+    return v4
+}
+
+; function %test1(i8, i8) -> i8 fast {
+; block0(v0: i8, v2: i8):
+;     v5 = icmp sgt v0, v2
+;     return v5
+; }
+

cranelift/filetests/filetests/runtests/icmp.clif

@@ -44,3 +44,24 @@ block0(v0: i32, v1: i32):
 ; run: %ule_sub_swap(1, -88) == 0
 ; run: %ule_sub_swap(1, 2) == 0
 ; run: %ule_sub_swap(2, 1) == 1
+
+function %fold_cmp_over_nots1(i8, i8) -> i8 {
+block0(v0: i8, v2: i8):
+    v1 = bnot v0
+    v3 = bnot v2
+    v4 = icmp ult v1, v3
+    return v4
+}
+
+; run: %fold_cmp_over_nots1(2, 1) == 1
+
+function %fold_cmp_over_nots2(i8, i8) -> i8 {
+block0(v0: i8, v2: i8):
+    v1 = bnot v0
+    v3 = bnot v2
+    v4 = icmp slt v1, v3
+    return v4
+}
+
+; run: %fold_cmp_over_nots2(2, 1) == 1
+