8251885: aarch64: aarch64-asmtest.py script generates unpredictable instructions

Reviewed-by: aph

src/hotspot/cpu/aarch64/aarch64-asmtest.py

@@ -741,6 +741,9 @@ class LoadStoreOp(InstructionWithModes):
 
         regMode = FloatRegister if isFloat else GeneralRegister
         self.reg = regMode().generate()
+        kindStr = Address.kindToStr(self.kind);
+        if (not isFloat) and (kindStr is "pre" or kindStr is "post"):
+            (self.reg.number, self.adr.base.number) = random.sample(range(31), 2)
         return self
 
     def cstr(self):
@@ -777,6 +780,14 @@ class LoadStorePairOp(InstructionWithModes):
           self.reg = [OperandFactory.create(self.mode).generate() 
                       for i in range(self.numRegs)]
           self.base = OperandFactory.create('x').generate()
+          kindStr = Address.kindToStr(self.kind);
+          if kindStr is "pre" or kindStr is "post":
+              if self._name.startswith("ld"):
+                  (self.reg[0].number, self.reg[1].number, self.base.number) = random.sample(range(31), 3)
+              if self._name.startswith("st"):
+                  self.base.number = random.choice(list(set(range(31)) - set([self.reg[0].number, self.reg[1].number])))
+          elif self._name.startswith("ld"):
+              (self.reg[0].number, self.reg[1].number) = random.sample(range(31), 2)
           return self
 
      def astr(self):
@@ -972,6 +983,8 @@ def generate(kind, names):
 
 outfile = open("aarch64ops.s", "w")
 
+random.seed(0)
+
 print "// BEGIN  Generated code -- do not edit"
 print "// Generated by aarch64-asmtest.py"