Reapply r372285 "GlobalISel: Don't materialize immarg arguments to intrinsics"

This reverts r372314, reapplying r372285 and the commits which depend
on it (r372286-r372293, and r372296-r372297)

This was missing one switch to getTargetConstant in an untested case.

llvm-svn: 372338
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.h b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.h
index 99564a0..855444f 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.h
@@ -83,6 +83,11 @@
                               MachineIRBuilder &B) const;
   bool legalizeIsAddrSpace(MachineInstr &MI, MachineRegisterInfo &MRI,
                            MachineIRBuilder &B, unsigned AddrSpace) const;
+
+  Register handleD16VData(MachineIRBuilder &B, MachineRegisterInfo &MRI,
+                          Register Reg) const;
+  bool legalizeRawBufferStore(MachineInstr &MI, MachineRegisterInfo &MRI,
+                              MachineIRBuilder &B, bool IsFormat) const;
   bool legalizeIntrinsic(MachineInstr &MI, MachineRegisterInfo &MRI,
                          MachineIRBuilder &B) const override;