[llvm] GlobalISel lane masks merging (PR #73337)

[Pierre van Houtryve via llvm-commits]

================
@@ -0,0 +1,79 @@
+#include "GCNSubtarget.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachinePostDominators.h"
+#include "llvm/CodeGen/MachineSSAUpdater.h"
+
+using namespace llvm;
----------------
Pierre-vh wrote:

Avoid `using namespace` in headers

https://github.com/llvm/llvm-project/pull/73337