[AMDGPU] Silence gcc 7 warnings

Differential Revision: https://reviews.llvm.org/D59330

llvm-svn: 356100
diff --git a/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp b/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
index 427e0c5..c5b3f34 100644
--- a/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
+++ b/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
@@ -102,14 +102,14 @@
 
     int64_t getFPModifiersOperand() const {
       int64_t Operand = 0;
-      Operand |= Abs ? SISrcMods::ABS : 0;
-      Operand |= Neg ? SISrcMods::NEG : 0;
+      Operand |= Abs ? SISrcMods::ABS : 0u;
+      Operand |= Neg ? SISrcMods::NEG : 0u;
       return Operand;
     }
 
     int64_t getIntModifiersOperand() const {
       int64_t Operand = 0;
-      Operand |= Sext ? SISrcMods::SEXT : 0;
+      Operand |= Sext ? SISrcMods::SEXT : 0u;
       return Operand;
     }