[Alignment] Use llvm::Align in MachineFunction and TargetLowering - fixes mir parsing

Summary:
This catches malformed mir files which specify alignment as log2 instead of pow2.
See https://reviews.llvm.org/D65945 for reference,

This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: MatzeB, qcolombet, dschuff, arsenm, sdardis, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, Petar.Avramovic, asbirlea, s.egerton, pzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67433

llvm-svn: 371608
diff --git a/llvm/lib/CodeGen/BranchRelaxation.cpp b/llvm/lib/CodeGen/BranchRelaxation.cpp
index 4ee61cf..d027d5b 100644
--- a/llvm/lib/CodeGen/BranchRelaxation.cpp
+++ b/llvm/lib/CodeGen/BranchRelaxation.cpp
@@ -64,19 +64,18 @@
     /// Compute the offset immediately following this block. \p MBB is the next
     /// block.
     unsigned postOffset(const MachineBasicBlock &MBB) const {
-      unsigned PO = Offset + Size;
-      unsigned LogAlign = MBB.getLogAlignment();
-      if (LogAlign == 0)
+      const unsigned PO = Offset + Size;
+      const llvm::Align Align = MBB.getAlignment();
+      if (Align == 1)
         return PO;
 
-      unsigned AlignAmt = 1 << LogAlign;
-      unsigned ParentLogAlign = MBB.getParent()->getLogAlignment();
-      if (LogAlign <= ParentLogAlign)
-        return PO + OffsetToAlignment(PO, AlignAmt);
+      const llvm::Align ParentAlign = MBB.getParent()->getAlignment();
+      if (Align <= ParentAlign)
+        return PO + OffsetToAlignment(PO, Align.value());
 
       // The alignment of this MBB is larger than the function's alignment, so we
       // can't tell whether or not it will insert nops. Assume that it will.
-      return PO + AlignAmt + OffsetToAlignment(PO, AlignAmt);
+      return PO + Align.value() + OffsetToAlignment(PO, Align.value());
     }
   };