[LLVM][Alignment] Make functions using log of alignment explicit

Summary:
This patch renames functions that takes or returns alignment as log2, this patch will help with the transition to llvm::Align.
The renaming makes it explicit that we deal with log(alignment) instead of a power of two alignment.
A few renames uncovered dubious assignments:

 - `MirParser`/`MirPrinter` was expecting powers of two but `MachineFunction` and `MachineBasicBlock` were using deal with log2(align). This patch fixes it and updates the documentation.
 - `MachineBlockPlacement` exposes two flags (`align-all-blocks` and `align-all-nofallthru-blocks`) supposedly interpreted as power of two alignments, internally these values are interpreted as log2(align). This patch updates the documentation,
 - `MachineFunctionexposes` exposes `align-all-functions` also interpreted as power of two alignment, internally this value is interpreted as log2(align). This patch updates the documentation,

Reviewers: lattner, thegameg, courbet

Subscribers: dschuff, arsenm, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, javed.absar, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, Jim, s.egerton, llvm-commits, courbet

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65945

llvm-svn: 371045

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/BranchRelaxation.cpp b/llvm/lib/CodeGen/BranchRelaxation.cpp
index 55fbf0163dd..4ee61cff4b4 100644
--- a/llvm/lib/CodeGen/BranchRelaxation.cpp
+++ b/llvm/lib/CodeGen/BranchRelaxation.cpp
@@ -65,13 +65,13 @@ class BranchRelaxation : public MachineFunctionPass {
     /// block.
     unsigned postOffset(const MachineBasicBlock &MBB) const {
       unsigned PO = Offset + Size;
-      unsigned Align = MBB.getAlignment();
-      if (Align == 0)
+      unsigned LogAlign = MBB.getLogAlignment();
+      if (LogAlign == 0)
         return PO;
 
-      unsigned AlignAmt = 1 << Align;
-      unsigned ParentAlign = MBB.getParent()->getAlignment();
-      if (Align <= ParentAlign)
+      unsigned AlignAmt = 1 << LogAlign;
+      unsigned ParentLogAlign = MBB.getParent()->getLogAlignment();
+      if (LogAlign <= ParentLogAlign)
         return PO + OffsetToAlignment(PO, AlignAmt);
 
       // The alignment of this MBB is larger than the function's alignment, so we
@@ -128,9 +128,9 @@ void BranchRelaxation::verify() {
 #ifndef NDEBUG
   unsigned PrevNum = MF->begin()->getNumber();
   for (MachineBasicBlock &MBB : *MF) {
-    unsigned Align = MBB.getAlignment();
+    unsigned LogAlign = MBB.getLogAlignment();
     unsigned Num = MBB.getNumber();
-    assert(BlockInfo[Num].Offset % (1u << Align) == 0);
+    assert(BlockInfo[Num].Offset % (1u << LogAlign) == 0);
     assert(!Num || BlockInfo[PrevNum].postOffset(MBB) <= BlockInfo[Num].Offset);
     assert(BlockInfo[Num].Size == computeBlockSize(MBB));
     PrevNum = Num;