PPC: Make Simulator respect C stack limits as well.

src/ppc/simulator-ppc.cc

Index: src/ppc/simulator-ppc.cc
diff --git a/src/ppc/simulator-ppc.cc b/src/ppc/simulator-ppc.cc
index bcc775370e79fac78092b316559f49db78955712..518f8fae758e682ff847a4184b8653054c51b3c8 100644
--- a/src/ppc/simulator-ppc.cc
+++ b/src/ppc/simulator-ppc.cc
@@ -1106,8 +1106,15 @@ void Simulator::WriteDW(intptr_t addr, int64_t value) {
 
 
 // Returns the limit of the stack area to enable checking for stack overflows.
-uintptr_t Simulator::StackLimit() const {
-  // Leave a safety margin to prevent overrunning the stack when pushing values.
+uintptr_t Simulator::StackLimit(uintptr_t c_limit) const {
+  // The simulator uses a separate JS stack. If we have exhausted the C stack,
+  // we also drop down the JS limit to reflect the exhaustion on the JS stack.
+  if (GetCurrentStackPosition() < c_limit) {
+    return reinterpret_cast<uintptr_t>(get_sp());
+  }
+
+  // Otherwise the limit is the JS stack. Leave a safety margin to prevent
+  // overrunning the stack when pushing values.
   return reinterpret_cast<uintptr_t>(stack_) + stack_protection_size_;
 }
 
@@ -3698,6 +3705,9 @@ void Simulator::Execute() {
 
 
 void Simulator::CallInternal(byte* entry) {
+  // Adjust JS-based stack limit to C-based stack limit.
+  isolate_->stack_guard()->AdjustStackLimitForSimulator();
+
 // Prepare to execute the code at entry
 #if ABI_USES_FUNCTION_DESCRIPTORS
   // entry is the function descriptor