[WebAssembly] Call signExtend to get sign extended register

Patch by Jatin Bhateja!

Differential Revision: https://reviews.llvm.org/D39529

llvm-svn: 317710
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
index f516a6b..e67b1c8 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
@@ -541,7 +541,7 @@
 unsigned WebAssemblyFastISel::getRegForSignedValue(const Value *V) {
   MVT::SimpleValueType From = getSimpleType(V->getType());
   MVT::SimpleValueType To = getLegalType(From);
-  return zeroExtend(getRegForValue(V), V, From, To);
+  return signExtend(getRegForValue(V), V, From, To);
 }
 
 unsigned WebAssemblyFastISel::getRegForPromotedValue(const Value *V,