Arm64: Fix filling static registers

Some locations could end up with SRA registers that only spilled one
register.
Allow passing in temporaries from the call site.
Fixes rpid and syscalls asserting.

FEXCore/Source/Interface/Core/ArchHelpers/Arm64Emitter.cpp

@@ -664,7 +664,8 @@ void Arm64Emitter::SpillStaticRegs(ARMEmitter::Register TmpReg, bool FPRs, uint3
   }
 }
 
-void Arm64Emitter::FillStaticRegs(bool FPRs, uint32_t GPRFillMask, uint32_t FPRFillMask) {
+void Arm64Emitter::FillStaticRegs(bool FPRs, uint32_t GPRFillMask, uint32_t FPRFillMask, std::optional<ARMEmitter::Register> OptionalReg,
+                                  std::optional<ARMEmitter::Register> OptionalReg2) {
   auto FindTempReg = [this](uint32_t* GPRFillMask) -> std::optional<ARMEmitter::Register> {
     for (auto Reg : StaticRegisters) {
       if (((1U << Reg.Idx()) & *GPRFillMask)) {
@@ -677,12 +678,18 @@ void Arm64Emitter::FillStaticRegs(bool FPRs, uint32_t GPRFillMask, uint32_t FPRF
 
   LOGMAN_THROW_A_FMT(GPRFillMask != 0, "Must fill at least 2 GPRs for a temp");
   uint32_t TempGPRFillMask = GPRFillMask;
-  auto Reg = FindTempReg(&TempGPRFillMask);
-  auto Reg2 = FindTempReg(&TempGPRFillMask);
-  LOGMAN_THROW_A_FMT(Reg.has_value() && Reg2.has_value(), "Didn't have an SRA register to use as a temporary while spilling!");
+  if (!OptionalReg.has_value()) {
+    OptionalReg = FindTempReg(&TempGPRFillMask);
+  }
+
+  if (!OptionalReg2.has_value()) {
+    OptionalReg2 = FindTempReg(&TempGPRFillMask);
+  }
+  LOGMAN_THROW_A_FMT(OptionalReg.has_value() && OptionalReg2.has_value(), "Didn't have an SRA register to use as a temporary while "
+                                                                          "spilling!");
 
-  auto TmpReg = *Reg;
-  [[maybe_unused]] auto TmpReg2 = *Reg2;
+  auto TmpReg = *OptionalReg;
+  [[maybe_unused]] auto TmpReg2 = *OptionalReg2;
 
 #ifndef VIXL_SIMULATOR
   if (EmitterCTX->HostFeatures.SupportsAFP) {

FEXCore/Source/Interface/Core/ArchHelpers/Arm64Emitter.h

@@ -102,7 +102,9 @@ class Arm64Emitter : public ARMEmitter::Emitter {
   //       and FPRs are being spilled or filled. If only GPRs are spilled/filled, then
   //       TMP4 is left alone.
   void SpillStaticRegs(ARMEmitter::Register TmpReg, bool FPRs = true, uint32_t GPRSpillMask = ~0U, uint32_t FPRSpillMask = ~0U);
-  void FillStaticRegs(bool FPRs = true, uint32_t GPRFillMask = ~0U, uint32_t FPRFillMask = ~0U);
+  void FillStaticRegs(bool FPRs = true, uint32_t GPRFillMask = ~0U, uint32_t FPRFillMask = ~0U,
+                      std::optional<ARMEmitter::Register> OptionalReg = std::nullopt,
+                      std::optional<ARMEmitter::Register> OptionalReg2 = std::nullopt);
 
   // Register 0-18 + 29 + 30 are caller saved
   static constexpr uint32_t CALLER_GPR_MASK = 0b0110'0000'0000'0111'1111'1111'1111'1111U;

FEXCore/Source/Interface/Core/JIT/Arm64/BranchOps.cpp

@@ -184,7 +184,7 @@ DEF_OP(Syscall) {
   if ((Flags & FEXCore::IR::SyscallFlags::NORETURN) != FEXCore::IR::SyscallFlags::NORETURN) {
     // Result is now in x0
     // Fix the stack and any values that were stepped on
-    FillStaticRegs(true, GPRSpillMask, FPRSpillMask);
+    FillStaticRegs(true, GPRSpillMask, FPRSpillMask, ARMEmitter::Reg::r1, ARMEmitter::Reg::r2);
 
     // Now the registers we've spilled are back in their original host registers
     // We can safely claim we are no longer in a syscall
@@ -285,7 +285,7 @@ DEF_OP(InlineSyscall) {
   if ((Op->Flags & FEXCore::IR::SyscallFlags::NORETURN) != FEXCore::IR::SyscallFlags::NORETURN) {
     // Now that we are done in the syscall we need to carefully peel back the state
     // First unspill the registers from before
-    FillStaticRegs(false, SpillMask);
+    FillStaticRegs(false, SpillMask, ~0U, ARMEmitter::Reg::r8, ARMEmitter::Reg::r1);
 
     // Now the registers we've spilled are back in their original host registers
     // We can safely claim we are no longer in a syscall

FEXCore/Source/Interface/Core/JIT/Arm64/MiscOps.cpp

@@ -233,7 +233,7 @@ DEF_OP(ProcessorID) {
 
   // Now that we are done in the syscall we need to carefully peel back the state
   // First unspill the registers from before
-  FillStaticRegs(false, SpillMask);
+  FillStaticRegs(false, SpillMask, ~0U, ARMEmitter::Reg::r8, ARMEmitter::Reg::r2);
 
   // Now the registers we've spilled are back in their original host registers
   // We can safely claim we are no longer in a syscall