Fix test Regression6046b.

src/compiler/mips/instruction-selector-mips.cc

Index: src/compiler/mips/instruction-selector-mips.cc
diff --git a/src/compiler/mips/instruction-selector-mips.cc b/src/compiler/mips/instruction-selector-mips.cc
index c8cfc09f69af5c08e582203e604b3884d26d93fc..a3cbfad548f29a3c934b0cac954386d5f3ac2f37 100644
--- a/src/compiler/mips/instruction-selector-mips.cc
+++ b/src/compiler/mips/instruction-selector-mips.cc
@@ -498,7 +498,7 @@ void InstructionSelector::VisitWord32Shr(Node* node) {
   if (m.left().IsWord32And() && m.right().HasValue()) {
     uint32_t lsb = m.right().Value() & 0x1f;
     Int32BinopMatcher mleft(m.left().node());
-    if (mleft.right().HasValue()) {
+    if (mleft.right().HasValue() && mleft.right().Value() != 0) {
       // Select Ext for Shr(And(x, mask), imm) where the result of the mask is
       // shifted into the least-significant bits.
       uint32_t mask = (mleft.right().Value() >> lsb) << lsb;