[WebAssembly] Add COMDAT support

This adds COMDAT support to the Wasm object-file format.
Spec: https://github.com/WebAssembly/tool-conventions/pull/31

Corresponding LLD change:
https://bugs.llvm.org/show_bug.cgi?id=35533, and D40845

Patch by Nicholas Wilson

Differential Revision: https://reviews.llvm.org/D40844

llvm-svn: 322135

1 files changed, 16 insertions, 6 deletions

diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
index 7d436180f03..80fd9a47a8d 100644
--- a/llvm/include/llvm/BinaryFormat/Wasm.h
+++ b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -95,6 +95,7 @@ struct WasmFunction {
   ArrayRef<uint8_t> Body;
   uint32_t CodeSectionOffset;
   uint32_t Size;
+  StringRef Comdat;
 };
 
 struct WasmDataSegment {
@@ -104,6 +105,7 @@ struct WasmDataSegment {
   StringRef Name;
   uint32_t Alignment;
   uint32_t Flags;
+  StringRef Comdat;
 };
 
 struct WasmElemSegment {
@@ -174,11 +176,6 @@ enum : unsigned {
 };
 
 enum : unsigned {
-  WASM_NAMES_FUNCTION = 0x1,
-  WASM_NAMES_LOCAL = 0x2,
-};
-
-enum : unsigned {
   WASM_LIMITS_FLAG_HAS_MAX = 0x1,
 };
 
@@ -190,12 +187,25 @@ enum class ValType {
   F64 = WASM_TYPE_F64,
 };
 
-// Linking metadata kinds.
+// Kind codes used in the custom "name" section
+enum : unsigned {
+  WASM_NAMES_FUNCTION = 0x1,
+  WASM_NAMES_LOCAL    = 0x2,
+};
+
+// Kind codes used in the custom "linking" section
 enum : unsigned {
   WASM_SYMBOL_INFO    = 0x2,
   WASM_DATA_SIZE      = 0x3,
   WASM_SEGMENT_INFO   = 0x5,
   WASM_INIT_FUNCS     = 0x6,
+  WASM_COMDAT_INFO    = 0x7,
+};
+
+// Kind codes used in the custom "linking" section in the WASM_COMDAT_INFO
+enum : unsigned {
+  WASM_COMDAT_DATA        = 0x0,
+  WASM_COMDAT_FUNCTION    = 0x1,
 };
 
 const unsigned WASM_SYMBOL_BINDING_MASK       = 0x3;