cmd/compile: Install testcases for flag constant Ops

Flag constant Ops on arm and arm64 are under refactoring, this change adds
a couple of testcases that verify the behavior of 'noov' branches.

Updates #39505
Updates #38740
Updates #39303
Change-Id: I493344b52276900cd296c32da494d72932dfc9be
Reviewed-on: https://go-review.googlesource.com/c/go/+/238677
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

test/fixedbugs/issue39505.go

@@ -0,0 +1,31 @@
+// compile
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f() {
+	if len([]int{})-1 < len([]int{}) {
+	}
+
+	var st struct {
+		i int
+	}
+	g := func() string {
+		return ""
+	}
+	h := func(string) string {
+		return g() + g()
+	}
+	s, i := "", 0
+
+	st.i = len(s)
+	i = len(h(s[i+0:i+1])) + len(s[len(s)+1:i+1])
+	s = s[(len(s[i+1:len(s)+1])+1):len(h(""))+1] + (s[i+1 : len([]int{})+i])
+	i = 1 + len([]int{len([]string{s[i+len([]int{}) : len(s)+i]})})
+
+	var ch chan int
+	ch <- len(h("")) - len(s)
+}

test/fixedbugs/issue39505b.go

@@ -0,0 +1,183 @@
+// run
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func main() {
+	ff := []func(){lt_f1, lt_f2, lt_f3, lt_f4, lt_f5, lt_f6, lt_f7, lt_f8, lt_f9,
+		gt_f1, gt_f2, gt_f3, le_f1, le_f2, le_f3, ge_f1, ge_f2, ge_f3}
+
+	for _, f := range ff {
+		f()
+	}
+}
+
+func lt_f1() {
+	const c = 1
+	var a = 0
+	var v *int = &a
+	if *v-c < len([]int{}) {
+	} else {
+		panic("bad")
+	}
+}
+
+func lt_f2() {
+	const c = 10
+	var a = 0
+	var v *int = &a
+	if *v+c < len([]int{}) {
+		panic("bad")
+	}
+}
+
+func lt_f3() {
+	const c = -10
+	var a = 0
+	var v *int = &a
+	if *v|0xff+c < len([]int{}) {
+		panic("bad")
+	}
+}
+
+func lt_f4() {
+	const c = 10
+	var a = 0
+	var v *int = &a
+	if *v|0x0f+c < len([]int{}) {
+		panic("bad")
+	}
+}
+
+func lt_f5() {
+	const c int32 = 1
+	var a int32 = 0
+	var v *int32 = &a
+	if *v-c < int32(len([]int32{})) {
+	} else {
+		panic("bad")
+	}
+}
+
+func lt_f6() {
+	const c int32 = 10
+	var a int32 = 0
+	var v *int32 = &a
+	if *v+c < int32(len([]int32{})) {
+		panic("bad")
+	}
+}
+
+func lt_f7() {
+	const c int32 = -10
+	var a int32 = 0
+	var v *int32 = &a
+	if *v|0xff+c < int32(len([]int{})) {
+		panic("bad")
+	}
+}
+
+func lt_f8() {
+	const c int32 = 10
+	var a int32 = 0
+	var v *int32 = &a
+	if *v|0x0f+c < int32(len([]int{})) {
+		panic("bad")
+	}
+}
+
+func lt_f9() {
+	const c int32 = -10
+	var a int32 = 0
+	var v *int32 = &a
+	if *v|0x0a+c < int32(len([]int{})) {
+		panic("bad")
+	}
+}
+
+func gt_f1() {
+	const c = 1
+	var a = 0
+	var v *int = &a
+	if len([]int{}) > *v-c {
+	} else {
+		panic("bad")
+	}
+}
+
+func gt_f2() {
+	const c = 10
+	var a = 0
+	var v *int = &a
+	if len([]int{}) > *v|0x0f+c {
+		panic("bad")
+	}
+}
+
+func gt_f3() {
+	const c int32 = 10
+	var a int32 = 0
+	var v *int32 = &a
+	if int32(len([]int{})) > *v|0x0f+c {
+		panic("bad")
+	}
+}
+
+func le_f1() {
+	const c = -10
+	var a = 0
+	var v *int = &a
+	if *v|0xff+c <= len([]int{}) {
+		panic("bad")
+	}
+}
+
+func le_f2() {
+	const c = 0xf
+	var a = 0
+	var v *int = &a
+	if *v|0xf-c <= len([]int{}) {
+	} else {
+		panic("bad")
+	}
+}
+
+func le_f3() {
+	const c int32 = -10
+	var a int32 = 0
+	var v *int32 = &a
+	if *v|0xff+c <= int32(len([]int{})) {
+		panic("bad")
+	}
+}
+
+func ge_f1() {
+	const c = -10
+	var a = 0
+	var v *int = &a
+	if len([]int{}) >= *v|0xff+c {
+		panic("bad")
+	}
+}
+
+func ge_f2() {
+	const c int32 = 10
+	var a int32 = 0
+	var v *int32 = &a
+	if int32(len([]int{})) >= *v|0x0f+c {
+		panic("bad")
+	}
+}
+
+func ge_f3() {
+	const c = -10
+	var a = 0
+	var v *int = &a
+	if len([]int{}) >= *v|0x0a+c {
+	} else {
+		panic("bad")
+	}
+}