[regexp] Port RegExpExecStub to CSA (mostly)

src/interface-descriptors.cc

Index: src/interface-descriptors.cc
diff --git a/src/interface-descriptors.cc b/src/interface-descriptors.cc
index 61a0d98229bcbe8edabdd138dec3d57b34cf4dd6..2de64b2af6037212540d2e0afd91e15926428751 100644
--- a/src/interface-descriptors.cc
+++ b/src/interface-descriptors.cc
@@ -492,6 +492,24 @@ void CallICTrampolineDescriptor::InitializePlatformIndependent(
                                       machine_types);
 }
 
+void RegExpExecDescriptor::InitializePlatformIndependent(
+    CallInterfaceDescriptorData* data) {
+  // kString, kLastIndex, kStringStart, kStringEnd, kEntryPoint
+  MachineType machine_types[] = {MachineType::AnyTagged(), MachineType::Int32(),
+                                 MachineType::Pointer(), MachineType::Pointer(),
+                                 MachineType::AnyTagged()};
+  data->InitializePlatformIndependent(arraysize(machine_types), 0,
+                                      machine_types);
+}
+
+void RegExpExecDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {StringRegister(), LastIndexRegister(),
+                          StringStartRegister(), StringEndRegister(),
+                          CodeRegister()};
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
 void BuiltinDescriptor::InitializePlatformIndependent(
     CallInterfaceDescriptorData* data) {
   // kTarget, kNewTarget, kArgumentsCount