This CL makes two main changes to allow internal/fuzz to support
-d=libfuzzer instrumentation:
1. It extends cmd/link to define _counters and _ecounters symbols so
internal/fuzz can find the coverage counters.
2. It adds "trace" stub functions that implement the ABI expected by
cmd/compile for comparison instrumentation.
N.B., that -tags=libfuzzer should *not* be set, so that
internal/fuzz's trace routines will be used instead of runtime's
libfuzzer trampolines.
Also, the current implementation doesn't support multi-module builds
(i.e., compiling a Go program that spans multiple .so/.dll files).
Presumably this isn't an issue, since "go test -fuzz" will need to
recompile the binary with instrumentation anyway so it can make sure
to always use a single-module build. But we can revisit this if
necessary.
Change-Id: I9b1619119ab7477bebcfd5988b4b60499a7ab0d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/308289
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Katie Hockman <katie@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
This change only includes a stub for the function
which will hook into the runtime to expose
coverage instrumentation while we're fuzzing.
Previously, we discussed an exported API named
FuzzCoverage, but since this is within the
internal/fuzz package, simply naming it coverage
seems appropriate.
Change-Id: Iba3240e53e0c4c434e937aa9bb1711a44fec9975
Reviewed-on: https://go-review.googlesource.com/c/go/+/308191
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
