[WebAssembly] Check return value of getRegForValue in FastISel

Previously, FastISel for WebAssembly wasn't checking the return value of
`getRegForValue` in certain cases, which would generate instructions
referencing NoReg. This patch fixes this behavior.

Patch by Dominic Chen

Differential Revision: https://reviews.llvm.org/D23100

llvm-svn: 277742

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
index b4786e5518f..2f409622795 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
@@ -388,6 +388,9 @@ unsigned WebAssemblyFastISel::getRegForI1Value(const Value *V, bool &Not) {
 
 unsigned WebAssemblyFastISel::zeroExtendToI32(unsigned Reg, const Value *V,
                                               MVT::SimpleValueType From) {
+  if (Reg == 0)
+    return 0;
+
   switch (From) {
   case MVT::i1:
     // If the value is naturally an i1, we don't need to mask it.
@@ -422,6 +425,9 @@ unsigned WebAssemblyFastISel::zeroExtendToI32(unsigned Reg, const Value *V,
 
 unsigned WebAssemblyFastISel::signExtendToI32(unsigned Reg, const Value *V,
                                               MVT::SimpleValueType From) {
+  if (Reg == 0)
+    return 0;
+
   switch (From) {
   case MVT::i1:
   case MVT::i8:
@@ -1121,6 +1127,8 @@ bool WebAssemblyFastISel::selectStore(const Instruction *I) {
   materializeLoadStoreOperands(Addr);
 
   unsigned ValueReg = getRegForValue(Store->getValueOperand());
+  if (ValueReg == 0)
+    return false;
   if (VTIsi1)
     ValueReg = maskI1Value(ValueReg, Store->getValueOperand());
 
@@ -1147,6 +1155,8 @@ bool WebAssemblyFastISel::selectBr(const Instruction *I) {
 
   bool Not;
   unsigned CondReg = getRegForI1Value(Br->getCondition(), Not);
+  if (CondReg == 0)
+    return false;
 
   unsigned Opc = WebAssembly::BR_IF;
   if (Not)
@@ -1214,6 +1224,9 @@ bool WebAssemblyFastISel::selectRet(const Instruction *I) {
   else
     Reg = getRegForValue(RV);
 
+  if (Reg == 0)
+    return false;
+
   BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc)).addReg(Reg);
   return true;
 }