AMDGPU: Fix a gcc warning

[nhaehnle]

Summary

.../AMDGPUAsmParser.cpp:1703:12: warning: suggest explicit braces to avoid

                                 ambiguous ‘else’ [-Wparentheses]
if (HwRegCode < 0 || HwRegCode > 63)
   ^

Seems like a good idea even without the warning.

[arsenm]

I think the same fix was already committed

[nhaehnle]

You're right, I hadn't pulled in the last few hours.

lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp

case AsmToken::Identifier: {
         int64_t HwRegCode = -1;
         int64_t Offset = 0; // default
         int64_t Width = 32; // default
         if (parseHwreg(HwRegCode, Offset, Width, IsIdentifier))
           return MatchOperand_ParseFail;
         // HwRegCode (6) [5:0]
         // Offset (5) [10:6]
         // WidthMinusOne (5) [15:11]
-        if (HwRegCode < 0 || HwRegCode > 63)
+        if (HwRegCode < 0 || HwRegCode > 63) {
           if (IsIdentifier)
             Error(S, "invalid symbolic name of hardware register");
           else
             Error(S, "invalid code of hardware register: only 6-bit values are legal");
+        }
         if (Offset < 0 || Offset > 31)
           Error(S, "invalid bit offset: only 5-bit values are legal");
         if (Width < 1 || Width > 32)
           Error(S, "invalid bitfield width: only values from 1 to 32 are legal");
         Imm16Val = HwRegCode | (Offset << 6) | ((Width-1) << 11);
       }
       break;
   }