cmd/compile, runtime: add comparison tracing for libFuzzer

This CL extends cmd/compile's experimental libFuzzer support with
calls to __sanitizer_cov_trace_{,const_}cmp{1,2,4,8}. This allows much
more efficient fuzzing of comparisons.

Only supports amd64 and arm64 for now.

Updates #14565.

Change-Id: Ibf82a8d9658f2bc50d955bdb1ae26723a3f0584d
Reviewed-on: https://go-review.googlesource.com/c/go/+/203887
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 75 insertions, 0 deletions

diff --git a/src/runtime/libfuzzer.go b/src/runtime/libfuzzer.go
new file mode 100644
index 0000000000..0161955f09
--- /dev/null
+++ b/src/runtime/libfuzzer.go
@@ -0,0 +1,75 @@
+// Copyright 2019 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.
+
+// +build libfuzzer
+
+package runtime
+
+import _ "unsafe" // for go:linkname
+
+func libfuzzerCall(fn *byte, arg0, arg1 uintptr)
+
+func libfuzzerTraceCmp1(arg0, arg1 uint8) {
+	libfuzzerCall(&__sanitizer_cov_trace_cmp1, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceCmp2(arg0, arg1 uint16) {
+	libfuzzerCall(&__sanitizer_cov_trace_cmp2, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceCmp4(arg0, arg1 uint32) {
+	libfuzzerCall(&__sanitizer_cov_trace_cmp4, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceCmp8(arg0, arg1 uint64) {
+	libfuzzerCall(&__sanitizer_cov_trace_cmp8, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceConstCmp1(arg0, arg1 uint8) {
+	libfuzzerCall(&__sanitizer_cov_trace_const_cmp1, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceConstCmp2(arg0, arg1 uint16) {
+	libfuzzerCall(&__sanitizer_cov_trace_const_cmp2, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceConstCmp4(arg0, arg1 uint32) {
+	libfuzzerCall(&__sanitizer_cov_trace_const_cmp4, uintptr(arg0), uintptr(arg1))
+}
+
+func libfuzzerTraceConstCmp8(arg0, arg1 uint64) {
+	libfuzzerCall(&__sanitizer_cov_trace_const_cmp8, uintptr(arg0), uintptr(arg1))
+}
+
+//go:linkname __sanitizer_cov_trace_cmp1 __sanitizer_cov_trace_cmp1
+//go:cgo_import_static __sanitizer_cov_trace_cmp1
+var __sanitizer_cov_trace_cmp1 byte
+
+//go:linkname __sanitizer_cov_trace_cmp2 __sanitizer_cov_trace_cmp2
+//go:cgo_import_static __sanitizer_cov_trace_cmp2
+var __sanitizer_cov_trace_cmp2 byte
+
+//go:linkname __sanitizer_cov_trace_cmp4 __sanitizer_cov_trace_cmp4
+//go:cgo_import_static __sanitizer_cov_trace_cmp4
+var __sanitizer_cov_trace_cmp4 byte
+
+//go:linkname __sanitizer_cov_trace_cmp8 __sanitizer_cov_trace_cmp8
+//go:cgo_import_static __sanitizer_cov_trace_cmp8
+var __sanitizer_cov_trace_cmp8 byte
+
+//go:linkname __sanitizer_cov_trace_const_cmp1 __sanitizer_cov_trace_const_cmp1
+//go:cgo_import_static __sanitizer_cov_trace_const_cmp1
+var __sanitizer_cov_trace_const_cmp1 byte
+
+//go:linkname __sanitizer_cov_trace_const_cmp2 __sanitizer_cov_trace_const_cmp2
+//go:cgo_import_static __sanitizer_cov_trace_const_cmp2
+var __sanitizer_cov_trace_const_cmp2 byte
+
+//go:linkname __sanitizer_cov_trace_const_cmp4 __sanitizer_cov_trace_const_cmp4
+//go:cgo_import_static __sanitizer_cov_trace_const_cmp4
+var __sanitizer_cov_trace_const_cmp4 byte
+
+//go:linkname __sanitizer_cov_trace_const_cmp8 __sanitizer_cov_trace_const_cmp8
+//go:cgo_import_static __sanitizer_cov_trace_const_cmp8
+var __sanitizer_cov_trace_const_cmp8 byte