[WebAssembly] Initialize memory in start function

Summary:
 - `__wasm_init_memory` is now the WebAssembly start function instead
   of being called from `__wasm_call_ctors` or called directly by the
   runtime.
 - Adds a new synthetic data symbol `__wasm_init_memory_flag` that is
   atomically incremented from zero to one by the thread responsible
   for initializing memory.
 - All threads now unconditionally perform data.drop on all passive
   segments.
 - Removes --passive-segments and --active-segments flags and controls
   segment type based on --shared-memory instead. The deleted flags
   were only present to ameliorate the upgrade path in Emscripten.

Reviewers: sbc100, aheejin

Subscribers: dschuff, jgravelle-google, sunfish, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65783

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@370965 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/BinaryFormat/Wasm.h b/include/llvm/BinaryFormat/Wasm.h
index 07548609f1a2bf713f1a377bf04df80e97907189..e2c94a12ad67905d6a37f5ee4d8a9fb49ee4b27b 100644 (file)
--- a/include/llvm/BinaryFormat/Wasm.h
+++ b/include/llvm/BinaryFormat/Wasm.h
@@ -251,9 +251,21 @@ enum : unsigned {
   WASM_OPCODE_F32_CONST = 0x43,
   WASM_OPCODE_F64_CONST = 0x44,
   WASM_OPCODE_I32_ADD = 0x6a,
+};
+
+// Opcodes used in synthetic functions.
+enum : unsigned {
+  WASM_OPCODE_IF = 0x04,
+  WASM_OPCODE_ELSE = 0x05,
+  WASM_OPCODE_DROP = 0x1a,
   WASM_OPCODE_MISC_PREFIX = 0xfc,
   WASM_OPCODE_MEMORY_INIT = 0x08,
   WASM_OPCODE_DATA_DROP = 0x09,
+  WASM_OPCODE_ATOMICS_PREFIX = 0xfe,
+  WASM_OPCODE_ATOMIC_NOTIFY = 0x00,
+  WASM_OPCODE_I32_ATOMIC_WAIT = 0x01,
+  WASM_OPCODE_I32_ATOMIC_STORE = 0x17,
+  WASM_OPCODE_I32_RMW_CMPXCHG = 0x48,
 };
 
 enum : unsigned {