[WebAssembly] Add option to emit passive segments

Summary:
Adds `--passive-segments` and `--active-segments` flags to control
what kind of segments are emitted. For now the default is always
to emit active segments so this is not a breaking change, but in
the future the default will be changed to passive segments when
shared memory is requested and active segments otherwise. When
passive segments are emitted, corresponding memory.init and
data.drop instructions are emitted in a `__wasm_init_memory`
function that is automatically called at the beginning of
`__wasm_call_ctors`.

Reviewers: sbc100, aheejin, dschuff

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59343

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@365088 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/BinaryFormat/Wasm.h b/include/llvm/BinaryFormat/Wasm.h
index 0f327c188bf3bb9c75cd4481ed13e092a70375a9..0ff52cbdb3375504063965b576968f65b12581ba 100644 (file)
--- a/include/llvm/BinaryFormat/Wasm.h
+++ b/include/llvm/BinaryFormat/Wasm.h
@@ -249,6 +249,9 @@ enum : unsigned {
   WASM_OPCODE_F32_CONST = 0x43,
   WASM_OPCODE_F64_CONST = 0x44,
   WASM_OPCODE_I32_ADD = 0x6a,
+  WASM_OPCODE_MISC_PREFIX = 0xfc,
+  WASM_OPCODE_MEMORY_INIT = 0x08,
+  WASM_OPCODE_DATA_DROP = 0x09,
 };
 
 enum : unsigned {