[ARM] Reserve scratch q-register.

src/register-configuration.cc

Index: src/register-configuration.cc
diff --git a/src/register-configuration.cc b/src/register-configuration.cc
index d4b90ca9265e4e86900d502d0b51ccddc608a3d8..af35fd3b03c77b1b42acefddc5a54cf76d9faaed 100644
--- a/src/register-configuration.cc
+++ b/src/register-configuration.cc
@@ -22,9 +22,13 @@ static const int kAllocatableGeneralCodes[] = {
     ALLOCATABLE_GENERAL_REGISTERS(REGISTER_CODE)};
 #undef REGISTER_CODE
 
-static const int kAllocatableDoubleCodes[] = {
 #define REGISTER_CODE(R) DoubleRegister::kCode_##R,
+static const int kAllocatableDoubleCodes[] = {
     ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_CODE)};
+#if V8_TARGET_ARCH_ARM
+static const int kAllocatableNoVFP32DoubleCodes[] = {
+    ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_CODE)};
+#endif  // V8_TARGET_ARCH_ARM
 #undef REGISTER_CODE
 
 static const char* const kGeneralRegisterNames[] = {
@@ -99,7 +103,14 @@ class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
 #else
 #error Unsupported target architecture.
 #endif
-            kAllocatableGeneralCodes, kAllocatableDoubleCodes,
+            kAllocatableGeneralCodes,
+#if V8_TARGET_ARCH_ARM
+            CpuFeatures::IsSupported(VFP32DREGS)
+                ? kAllocatableDoubleCodes
+                : kAllocatableNoVFP32DoubleCodes,
+#else
+            kAllocatableDoubleCodes,
+#endif
             kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE,
             kGeneralRegisterNames, kFloatRegisterNames, kDoubleRegisterNames,
             kSimd128RegisterNames) {