1 files changed, 88 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/testdata/gen/zeroGen.go b/src/cmd/compile/internal/gc/testdata/gen/zeroGen.go
new file mode 100644
index 0000000000..90e8029f3f
--- /dev/null
+++ b/src/cmd/compile/internal/gc/testdata/gen/zeroGen.go
@@ -0,0 +1,88 @@
+// Copyright 2015 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
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"io/ioutil"
+	"log"
+)
+
+// This program generates tests to verify that zeroing operations
+// zero the data they are supposed to and clobber no adjacent values.
+
+// run as `go run zeroGen.go`.  A file called zero_ssa.go
+// will be written into the parent directory containing the tests.
+
+var sizes = [...]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 23, 24, 25, 31, 32, 33, 63, 64, 65, 1023, 1024, 1025}
+
+func main() {
+	w := new(bytes.Buffer)
+	fmt.Fprintf(w, "// run\n")
+	fmt.Fprintf(w, "// autogenerated from gen/zeroGen.go - do not edit!\n")
+	fmt.Fprintf(w, "package main\n")
+	fmt.Fprintf(w, "import \"fmt\"\n")
+
+	for _, s := range sizes {
+		// type for test
+		fmt.Fprintf(w, "type T%d struct {\n", s)
+		fmt.Fprintf(w, "  pre [8]byte\n")
+		fmt.Fprintf(w, "  mid [%d]byte\n", s)
+		fmt.Fprintf(w, "  post [8]byte\n")
+		fmt.Fprintf(w, "}\n")
+
+		// function being tested
+		fmt.Fprintf(w, "func zero%d_ssa(x *[%d]byte) {\n", s, s)
+		fmt.Fprintf(w, "  switch{}\n")
+		fmt.Fprintf(w, "  *x = [%d]byte{}\n", s)
+		fmt.Fprintf(w, "}\n")
+
+		// testing harness
+		fmt.Fprintf(w, "func testZero%d() {\n", s)
+		fmt.Fprintf(w, "  a := T%d{[8]byte{255,255,255,255,255,255,255,255},[%d]byte{", s, s)
+		for i := 0; i < s; i++ {
+			fmt.Fprintf(w, "255,")
+		}
+		fmt.Fprintf(w, "},[8]byte{255,255,255,255,255,255,255,255}}\n")
+		fmt.Fprintf(w, "  zero%d_ssa(&a.mid)\n", s)
+		fmt.Fprintf(w, "  want := T%d{[8]byte{255,255,255,255,255,255,255,255},[%d]byte{", s, s)
+		for i := 0; i < s; i++ {
+			fmt.Fprintf(w, "0,")
+		}
+		fmt.Fprintf(w, "},[8]byte{255,255,255,255,255,255,255,255}}\n")
+		fmt.Fprintf(w, "  if a != want {\n")
+		fmt.Fprintf(w, "    fmt.Printf(\"zero%d got=%%v, want %%v\\n\", a, want)\n", s)
+		fmt.Fprintf(w, "    failed=true\n")
+		fmt.Fprintf(w, "  }\n")
+		fmt.Fprintf(w, "}\n")
+	}
+
+	// boilerplate at end
+	fmt.Fprintf(w, "var failed bool\n")
+	fmt.Fprintf(w, "func main() {\n")
+	for _, s := range sizes {
+		fmt.Fprintf(w, "  testZero%d()\n", s)
+	}
+	fmt.Fprintf(w, "  if failed {\n")
+	fmt.Fprintf(w, "    panic(\"failed\")\n")
+	fmt.Fprintf(w, "  }\n")
+	fmt.Fprintf(w, "}\n")
+
+	// gofmt result
+	b := w.Bytes()
+	src, err := format.Source(b)
+	if err != nil {
+		fmt.Printf("%s\n", b)
+		panic(err)
+	}
+
+	// write to file
+	err = ioutil.WriteFile("../zero_ssa.go", src, 0666)
+	if err != nil {
+		log.Fatalf("can't write output: %v\n", err)
+	}
+}