PPC/s390: [crankshaft] Fix Smi overflow in {HMaybeGrowElements}.

src/crankshaft/ppc/lithium-codegen-ppc.cc

Index: src/crankshaft/ppc/lithium-codegen-ppc.cc
diff --git a/src/crankshaft/ppc/lithium-codegen-ppc.cc b/src/crankshaft/ppc/lithium-codegen-ppc.cc
index f870361144063caa6ff9c23dd8aec45869dec247..ac955613f0ebb1750a1a4996ae8533a0acd9410c 100644
--- a/src/crankshaft/ppc/lithium-codegen-ppc.cc
+++ b/src/crankshaft/ppc/lithium-codegen-ppc.cc
@@ -4354,12 +4354,21 @@ void LCodeGen::DoDeferredMaybeGrowElements(LMaybeGrowElements* instr) {
       if (Smi::IsValid(int_key)) {
         __ LoadSmiLiteral(r6, Smi::FromInt(int_key));
       } else {
-        // We should never get here at runtime because there is a smi check on
-        // the key before this point.
-        __ stop("expected smi");
+        Abort(kArrayIndexConstantValueTooBig);
       }
     } else {
+      Label is_smi;
+#if V8_TARGET_ARCH_PPC64
       __ SmiTag(r6, ToRegister(key));
+#else
+      // Deopt if the key is outside Smi range. The stub expects Smi and would
+      // bump the elements into dictionary mode (and trigger a deopt) anyways.
+      __ SmiTagCheckOverflow(r6, ToRegister(key), r0);
+      __ BranchOnNoOverflow(&is_smi);
+      __ PopSafepointRegisters();
+      DeoptimizeIf(al, instr, DeoptimizeReason::kOverflow, cr0);
+      __ bind(&is_smi);
+#endif
     }
 
     GrowArrayElementsStub stub(isolate(), instr->hydrogen()->kind());