cmd/compile: teach prove about bitwise OR operation

Fixes #45928.

Change-Id: Ifbb0effbca4ab7c0eb56069fee40edb564553c35
Reviewed-on: https://go-review.googlesource.com/c/go/+/410336
Reviewed-by: Cuong Manh Le <[email protected]>
Run-TryBot: Wayne Zuo <[email protected]>
Reviewed-by: David Chase <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: wdvxdr1123

src/cmd/compile/internal/ssa/prove.go

@@ -842,6 +842,9 @@ func prove(f *Func) {
 			case OpAnd64, OpAnd32, OpAnd16, OpAnd8:
 				ft.update(b, v, v.Args[1], unsigned, lt|eq)
 				ft.update(b, v, v.Args[0], unsigned, lt|eq)
+			case OpOr64, OpOr32, OpOr16, OpOr8:
+				ft.update(b, v, v.Args[1], unsigned, gt|eq)
+				ft.update(b, v, v.Args[0], unsigned, gt|eq)
 			}
 		}
 	}

test/prove.go

@@ -1053,6 +1053,11 @@ func issue51622(b []byte) int {
 	return 0
 }
 
+func issue45928(x int) {
+	combinedFrac := (x) / (x | (1 << 31)) // ERROR "Proved Neq64$"
+	useInt(combinedFrac)
+}
+
 //go:noinline
 func useInt(a int) {
 }