From c551522d250ae53d7cac031f91f9c605c02893e7 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Sun, 17 Dec 2017 17:50:07 +0000
Subject: [PATCH] [WebAssembly] Export some more info on wasm funtions

Summary:
These fields are useful for lld's gc-sections support

Also remove an unused field.

Subscribers: jfb, dschuff, jgravelle-google, aheejin, sunfish

Differential Revision: https://reviews.llvm.org/D41320

llvm-svn: 320946
---
 llvm/include/llvm/BinaryFormat/Wasm.h |  2 ++
 llvm/include/llvm/Object/Wasm.h       |  2 --
 llvm/lib/Object/WasmObjectFile.cpp    | 11 +++++++----
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
index a21f28c41965..48847002c82a 100644
--- a/llvm/include/llvm/BinaryFormat/Wasm.h
+++ b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -91,6 +91,8 @@ struct WasmLocalDecl {
 struct WasmFunction {
   std::vector<WasmLocalDecl> Locals;
   ArrayRef<uint8_t> Body;
+  size_t CodeSectionOffset;
+  size_t Size;
 };
 
 struct WasmDataSegment {
diff --git a/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
index a129aeef4f49..5bb1a3fca3d1 100644
--- a/llvm/include/llvm/Object/Wasm.h
+++ b/llvm/include/llvm/Object/Wasm.h
@@ -140,7 +140,6 @@ public:
   ArrayRef<wasm::WasmElemSegment> elements() const { return ElemSegments; }
   ArrayRef<WasmSegment> dataSegments() const { return DataSegments; }
   ArrayRef<wasm::WasmFunction> functions() const { return Functions; }
-  const ArrayRef<uint8_t>& code() const { return CodeSection; }
   uint32_t startFunction() const { return StartFunction; }
 
   void moveSymbolNext(DataRefImpl &Symb) const override;
@@ -242,7 +241,6 @@ private:
   std::vector<WasmSegment> DataSegments;
   std::vector<wasm::WasmFunction> Functions;
   std::vector<WasmSymbol> Symbols;
-  ArrayRef<uint8_t> CodeSection;
   uint32_t StartFunction = -1;
   bool HasLinkingSection = false;
   wasm::WasmLinkingData LinkingData;
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 41377579ae0f..7a0c05ed8a15 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -684,18 +684,21 @@ Error WasmObjectFile::parseStartSection(const uint8_t *Ptr, const uint8_t *End)
 }
 
 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
+  const uint8_t *CodeSectionStart = Ptr;
   uint32_t FunctionCount = readVaruint32(Ptr);
   if (FunctionCount != FunctionTypes.size()) {
     return make_error<GenericBinaryError>("Invalid function count",
                                           object_error::parse_failed);
   }
 
-  CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
-
   while (FunctionCount--) {
     wasm::WasmFunction Function;
-    uint32_t FunctionSize = readVaruint32(Ptr);
-    const uint8_t *FunctionEnd = Ptr + FunctionSize;
+    const uint8_t *FunctionStart = Ptr;
+    uint32_t Size = readVaruint32(Ptr);
+    const uint8_t *FunctionEnd = Ptr + Size;
+
+    Function.CodeSectionOffset = FunctionStart - CodeSectionStart;
+    Function.Size = FunctionEnd - FunctionStart;
 
     uint32_t NumLocalDecls = readVaruint32(Ptr);
     Function.Locals.reserve(NumLocalDecls);