[WebAssembly] Added basic support for if/else/end_if in MC layer.

Summary:
These instructions are currently unused in our backend, but for
completeness it is good to support them, so they can be used with
the assembler in hand-written code.

Tests are very basic, signature support missing much like other blocks.

Reviewers: dschuff, aheejin

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D55973

llvm-svn: 350079

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 62229d390b3..d997190aa36 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -488,7 +488,8 @@ public:
     // assembly, so we add a dummy one explicitly (since we have no control
     // over signature tables here, we assume these will be regenerated when
     // the wasm module is generated).
-    if (BaseName == "block" || BaseName == "loop" || BaseName == "try") {
+    if (BaseName == "block" || BaseName == "loop" || BaseName == "try" ||
+        BaseName == "if") {
       Operands.push_back(make_unique<WebAssemblyOperand>(
           WebAssemblyOperand::Integer, NameLoc, NameLoc,
           WebAssemblyOperand::IntOp{-1}));