Use C preprocessor comments in assembly headers.

We generate .S files for assembly, which means they run through the C
preprocessor first. In gas targets where # is the comment marker, there
is a conflict with cpp directives.

The comments actually rely on #This and #source not being directives. If
I begin a line with "if", the build fails. Since the C preprocessor is
responsible for removing C preprocessor comments, we should be able to
safely use // everywhere with less ambiguity.

(In fact, we were already relying on this for 32-bit ARM. The 32-bit ARM
gas line comment marker is @. 64-bit ARM uses //, and x86/x86_64/ppc64
use #.)

This reportedly causes issues for goma. See

Bug: 448
Change-Id: Ib58f3152691c1dbcccfc045f21f486b56824283d
Reviewed-by: Adam Langley <>
3 files changed
tree: 6a1f63107ca7e834eae75c613cf860cf5416c540
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. ssl/
  7. third_party/
  8. tool/
  9. util/
  10. .clang-format
  11. .gitignore
  15. CMakeLists.txt
  24. codereview.settings
  25. go.mod
  26. go.sum
  27. sources.cmake


BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

Project links:

There are other files in this directory which might be helpful: