1 files changed, 108 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/flags_test.go b/src/cmd/compile/internal/ssa/flags_test.go
new file mode 100644
index 0000000..d0079ac
--- /dev/null
+++ b/src/cmd/compile/internal/ssa/flags_test.go
@@ -0,0 +1,108 @@
+// 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.
+
+//go:build amd64 || arm64
+
+package ssa
+
+// This file tests the functions addFlags64 and subFlags64 by comparing their
+// results to what the chip calculates.
+
+import (
+	"runtime"
+	"testing"
+)
+
+func TestAddFlagsNative(t *testing.T) {
+	var numbers = []int64{
+		1, 0, -1,
+		2, -2,
+		1<<63 - 1, -1 << 63,
+	}
+	coverage := map[flagConstant]bool{}
+	for _, x := range numbers {
+		for _, y := range numbers {
+			a := addFlags64(x, y)
+			b := flagRegister2flagConstant(asmAddFlags(x, y), false)
+			if a != b {
+				t.Errorf("asmAdd diff: x=%x y=%x got=%s want=%s\n", x, y, a, b)
+			}
+			coverage[a] = true
+		}
+	}
+	if len(coverage) != 9 { // TODO: can we cover all outputs?
+		t.Errorf("coverage too small, got %d want 9", len(coverage))
+	}
+}
+
+func TestSubFlagsNative(t *testing.T) {
+	var numbers = []int64{
+		1, 0, -1,
+		2, -2,
+		1<<63 - 1, -1 << 63,
+	}
+	coverage := map[flagConstant]bool{}
+	for _, x := range numbers {
+		for _, y := range numbers {
+			a := subFlags64(x, y)
+			b := flagRegister2flagConstant(asmSubFlags(x, y), true)
+			if a != b {
+				t.Errorf("asmSub diff: x=%x y=%x got=%s want=%s\n", x, y, a, b)
+			}
+			coverage[a] = true
+		}
+	}
+	if len(coverage) != 7 { // TODO: can we cover all outputs?
+		t.Errorf("coverage too small, got %d want 7", len(coverage))
+	}
+}
+
+func TestAndFlagsNative(t *testing.T) {
+	var numbers = []int64{
+		1, 0, -1,
+		2, -2,
+		1<<63 - 1, -1 << 63,
+	}
+	coverage := map[flagConstant]bool{}
+	for _, x := range numbers {
+		for _, y := range numbers {
+			a := logicFlags64(x & y)
+			b := flagRegister2flagConstant(asmAndFlags(x, y), false)
+			if a != b {
+				t.Errorf("asmAnd diff: x=%x y=%x got=%s want=%s\n", x, y, a, b)
+			}
+			coverage[a] = true
+		}
+	}
+	if len(coverage) != 3 {
+		t.Errorf("coverage too small, got %d want 3", len(coverage))
+	}
+}
+
+func asmAddFlags(x, y int64) int
+func asmSubFlags(x, y int64) int
+func asmAndFlags(x, y int64) int
+
+func flagRegister2flagConstant(x int, sub bool) flagConstant {
+	var fcb flagConstantBuilder
+	switch runtime.GOARCH {
+	case "amd64":
+		fcb.Z = x>>6&1 != 0
+		fcb.N = x>>7&1 != 0
+		fcb.C = x>>0&1 != 0
+		if sub {
+			// Convert from amd64-sense to arm-sense
+			fcb.C = !fcb.C
+		}
+		fcb.V = x>>11&1 != 0
+	case "arm64":
+		fcb.Z = x>>30&1 != 0
+		fcb.N = x>>31&1 != 0
+		fcb.C = x>>29&1 != 0
+		fcb.V = x>>28&1 != 0
+	default:
+		panic("unsupported architecture: " + runtime.GOARCH)
+	}
+	return fcb.encode()
+}