[WebAssembly] Fixed objdump not parsing function headers.

Summary:
objdump was interpreting the function header containing the locals
declaration as instructions. To parse these without injecting target
specific code in objdump, MCDisassembler::onSymbolStart was added to
be implemented by the WebAssembly implemention.

WasmObjectFile now returns a code offset for the "address" of a symbol,
rather than the index. This is also more in-line with what other
targets do.

Also ensured that the AsmParser correctly puts each function
in its own segment to enable this test case.

Reviewers: sbc100, dschuff

Subscribers: jgravelle-google, aheejin, sunfish, rupprecht, llvm-commits

Differential Revision: https://reviews.llvm.org/D56684

llvm-svn: 351460

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp b/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
index 2f1275d..0959881 100644
--- a/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
+++ b/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
@@ -8,6 +8,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 
@@ -15,6 +17,13 @@ using namespace llvm;
 
 MCDisassembler::~MCDisassembler() = default;
 
+MCDisassembler::DecodeStatus MCDisassembler::onSymbolStart(
+    StringRef Name, uint64_t &Size, ArrayRef<uint8_t> Bytes, uint64_t Address,
+    raw_ostream &VStream, raw_ostream &CStream) const {
+  Size = 0;
+  return MCDisassembler::Success;
+}
+
 bool MCDisassembler::tryAddingSymbolicOperand(MCInst &Inst, int64_t Value,
                                               uint64_t Address, bool IsBranch,
                                               uint64_t Offset,