Merge pull request #9787 from JosJuice/jitarm64-slwx-top

JitArm64: Discard top 32 bits in slwx result

Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp

@@ -1451,15 +1451,12 @@ void JitArm64::slwx(UGeckoInstruction inst)
   {
     gpr.BindToRegister(a, a == b || a == s);
 
-    // PowerPC any shift in the 32-63 register range results in zero
-    // Since it has 32bit registers
-    // AArch64 it will use a mask of the register size for determining what shift amount
-    // So if we use a 64bit so the bits will end up in the high 32bits, and
-    // Later instructions will just eat high 32bits since it'll run 32bit operations for everything.
+    // On PowerPC, shifting a 32-bit register by an amount from 32 to 63 results in 0.
+    // We emulate this by using a 64-bit operation and then discarding the top 32 bits.
     LSLV(EncodeRegTo64(gpr.R(a)), EncodeRegTo64(gpr.R(s)), EncodeRegTo64(gpr.R(b)));
-
     if (inst.Rc)
       ComputeRC0(gpr.R(a));
+    MOV(gpr.R(a), gpr.R(a));
   }
 }
 
@@ -1499,10 +1496,6 @@ void JitArm64::srwx(UGeckoInstruction inst)
   {
     gpr.BindToRegister(a, a == b || a == s);
 
-    // wipe upper bits. TODO: get rid of it, but then no instruction is allowed to emit some higher
-    // bits.
-    MOV(gpr.R(s), gpr.R(s));
-
     LSRV(EncodeRegTo64(gpr.R(a)), EncodeRegTo64(gpr.R(s)), EncodeRegTo64(gpr.R(b)));
 
     if (inst.Rc)