[llvm] [AMDGPU][GlobalISel] Minor G_BITCAST improvements and a fix to the artifact combiner (PR #215703)

[Matt Arsenault via llvm-commits]

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@@ -71,9 +71,13 @@ class LegalizationArtifactCombiner {
     Register TruncSrc;
     if (mi_match(SrcReg, MRI, m_GTrunc(m_Reg(TruncSrc)))) {
       LLVM_DEBUG(dbgs() << ".. Combine MI: " << MI);
-      if (MRI.getType(DstReg) == MRI.getType(TruncSrc))
+      auto DstType = MRI.getType(DstReg);
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arsenm wrote:

No auto 

https://github.com/llvm/llvm-project/pull/215703