adjust allocregs() for complex types (dlang#22537)

Author: WalterBright

compiler/src/dmd/backend/x86/cgcod.d

@@ -1680,23 +1680,35 @@ static if (0)
         if ((retregs & cgstate.regcon.mvar) == retregs) // if exactly in reg vars
         {
             reg_t outreg;
-            if (size <= REGSIZE || (retregs & XMMREGS) || (retregs & INSTR.FLOATREGS))
-            {
-                outreg = findreg(retregs);
-                assert(retregs == mask(outreg)); /* no more bits are set */
-            }
-            else if (size <= 2 * REGSIZE)
+            if (AArch64)
             {
-                if (AArch64)
+                if (tycomplex(tym))
                 {
                     outreg = findreg(retregs & INSTR.MSW);
                     assert(retregs & INSTR.LSW);
                 }
-                else
+                else if (size <= REGSIZE || (retregs & INSTR.FLOATREGS))
+                {
+                    outreg = findreg(retregs);
+                    assert(retregs == mask(outreg));
+                }
+                else if (size <= 2 * REGSIZE)
                 {
-                    outreg = findregmsw(retregs);
-                    assert(retregs & mLSW);
+                    outreg = findreg(retregs & INSTR.MSW);
+                    assert(retregs & INSTR.LSW);
                 }
+                else
+                    assert(0);
+            }
+            else if (size <= REGSIZE || (retregs & XMMREGS))
+            {
+                outreg = findreg(retregs);
+                assert(retregs == mask(outreg)); /* no more bits are set */
+            }
+            else if (size <= 2 * REGSIZE)
+            {
+                outreg = findregmsw(retregs);
+                assert(retregs & mLSW);
             }
             else
                 assert(0);