[Remarks] Add support for linking remarks

Remarks are usually emitted per-TU, and for generating a standalone
remark file that can be shipped with the linked binary we need some kind
of tool to merge everything together.

The remarks::RemarkLinker class takes care of this and:

* Deduplicates remarks
* Filters remarks with no debug location
* Merges string tables from all the entries

As an output, it provides an iterator range that can be used to
serialize the remarks to a file.

Differential Revision: https://reviews.llvm.org/D69141

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Remarks/RemarkFormat.cpp b/llvm/lib/Remarks/RemarkFormat.cpp
index f2d0331ec6a..c7fce151eff 100644
--- a/llvm/lib/Remarks/RemarkFormat.cpp
+++ b/llvm/lib/Remarks/RemarkFormat.cpp
@@ -12,6 +12,7 @@
 
 #include "llvm/Remarks/RemarkFormat.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Remarks/BitstreamRemarkContainer.h"
 
 using namespace llvm;
 using namespace llvm::remarks;
@@ -30,3 +31,17 @@ Expected<Format> llvm::remarks::parseFormat(StringRef FormatStr) {
 
   return Result;
 }
+
+Expected<Format> llvm::remarks::magicToFormat(StringRef Magic) {
+  auto Result =
+      StringSwitch<Format>(Magic)
+          .StartsWith("--- ", Format::YAML) // This is only an assumption.
+          .StartsWith(remarks::Magic, Format::YAMLStrTab)
+          .StartsWith(remarks::ContainerMagic, Format::Bitstream)
+          .Default(Format::Unknown);
+
+  if (Result == Format::Unknown)
+    return createStringError(std::make_error_code(std::errc::invalid_argument),
+                             "Unknown remark magic: '%s'", Magic.data());
+  return Result;
+}