CPU/Recompiler/AArch64: Use cmn for negative constant comparisons

src/core/cpu_recompiler_code_generator.cpp

@@ -1522,8 +1522,8 @@ bool CodeGenerator::Compile_SignedDivide(const CodeBlockInstruction& cbi)
     // else if (static_cast<u32>(num) == UINT32_C(0x80000000) && denom == -1)
     {
       EmitBindLabel(&not_zero);
-      EmitConditionalBranch(Condition::NotEqual, false, denom_reg.GetHostRegister(),
-                            Value::FromConstantU32(0xFFFFFFFFu), &do_divide);
+      EmitConditionalBranch(Condition::NotEqual, false, denom_reg.GetHostRegister(), Value::FromConstantS32(-1),
+                            &do_divide);
       EmitConditionalBranch(Condition::NotEqual, false, num_reg.GetHostRegister(), lo, &do_divide);
 
       // unrepresentable

src/core/cpu_recompiler_code_generator_aarch64.cpp

@@ -465,14 +465,29 @@ void CodeGenerator::EmitCmp(HostReg to_reg, const Value& value)
 
   // do we need temporary storage for the constant, if it won't fit in an immediate?
   const s64 constant_value = value.GetS64ConstantValue();
-  if (a64::Assembler::IsImmAddSub(constant_value))
+  if (constant_value >= 0)
   {
-    if (value.size < RegSize_64)
-      m_emit->cmp(GetHostReg32(to_reg), constant_value);
-    else
-      m_emit->cmp(GetHostReg64(to_reg), constant_value);
+    if (a64::Assembler::IsImmAddSub(constant_value))
+    {
+      if (value.size < RegSize_64)
+        m_emit->cmp(GetHostReg32(to_reg), constant_value);
+      else
+        m_emit->cmp(GetHostReg64(to_reg), constant_value);
 
-    return;
+      return;
+    }
+  }
+  else
+  {
+    if (a64::Assembler::IsImmAddSub(-constant_value))
+    {
+      if (value.size < RegSize_64)
+        m_emit->cmn(GetHostReg32(to_reg), -constant_value);
+      else
+        m_emit->cmn(GetHostReg64(to_reg), -constant_value);
+
+      return;
+    }
   }
 
   // need a temporary

src/core/cpu_recompiler_register_cache.h

@@ -191,6 +191,7 @@ struct Value
   static Value FromConstantU8(u8 value) { return FromConstant(ZeroExtend64(value), RegSize_8); }
   static Value FromConstantU16(u16 value) { return FromConstant(ZeroExtend64(value), RegSize_16); }
   static Value FromConstantU32(u32 value) { return FromConstant(ZeroExtend64(value), RegSize_32); }
+  static Value FromConstantS32(s32 value) { return FromConstant(ZeroExtend64(static_cast<u32>(value)), RegSize_32); }
   static Value FromConstantU64(u64 value) { return FromConstant(value, RegSize_64); }
 
 private: