[StackMaps] Add a lightweight parser for stackmap version 1 sections.

The parser provides a convenient interface for reading llvm stackmap v1 sections
in object files.

This patch also includes a new option for llvm-readobj, '-stackmap', which uses
the parser to pretty-print stackmap sections for debugging/testing purposes.

llvm-svn: 240860

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 630f0ee5fb8..4efd8cb07ea 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -17,6 +17,7 @@
 #include "ARMEHABIPrinter.h"
 #include "Error.h"
 #include "ObjDumper.h"
+#include "StackMapPrinter.h"
 #include "StreamWriter.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallString.h"
@@ -61,6 +62,8 @@ public:
   void printMipsABIFlags() override;
   void printMipsReginfo() override;
 
+  void printStackMap() const override;
+
 private:
   typedef ELFFile<ELFT> ELFO;
   typedef typename ELFO::Elf_Shdr Elf_Shdr;
@@ -1494,3 +1497,25 @@ template <class ELFT> void ELFDumper<ELFT>::printMipsReginfo() {
   W.printHex("Co-Proc Mask2", Reginfo->ri_cprmask[2]);
   W.printHex("Co-Proc Mask3", Reginfo->ri_cprmask[3]);
 }
+
+template <class ELFT> void ELFDumper<ELFT>::printStackMap() const {
+  const typename ELFFile<ELFT>::Elf_Shdr *StackMapSection = nullptr;
+  for (const auto &Sec : Obj->sections()) {
+    ErrorOr<StringRef> Name = Obj->getSectionName(&Sec);
+    if (*Name == ".llvm_stackmaps") {
+      StackMapSection = &Sec;
+      break;
+    }
+  }
+
+  if (!StackMapSection)
+    return;
+
+  StringRef StackMapContents;
+  ErrorOr<ArrayRef<uint8_t>> StackMapContentsArray =
+    Obj->getSectionContents(StackMapSection);
+
+  prettyPrintStackMap(
+              llvm::outs(),
+              StackMapV1Parser<ELFT::TargetEndianness>(*StackMapContentsArray));
+}