From c68f8f2fd3c004e60e958761b00a9ae4bce97e2d Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Fri, 14 Jul 2017 18:30:09 +0000
Subject: [PATCH] [TableGen][MC] Fix a few places where we didn't hide the
 underlying type of LaneBitmask very well.

One place compared with 32, which I've replaced with LaneBitmask::BitWidth.

The other places are shifts of a constant 1 by a lane number. But if LaneBitmask were to be a larger type than 32-bits like 64-bits, the 1 would need to be 1ULL to do a 64-bit shift. To hide this I've added a LanebitMask::getLane that hides the shift and make sures the 1 is casted to correct type first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308042 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/MC/LaneBitmask.h       |  3 +++
 utils/TableGen/CodeGenRegisters.cpp | 12 ++++++------
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/llvm/MC/LaneBitmask.h b/include/llvm/MC/LaneBitmask.h
index 5ca06d1148e..73b987b074d 100644
--- a/include/llvm/MC/LaneBitmask.h
+++ b/include/llvm/MC/LaneBitmask.h
@@ -75,6 +75,9 @@ namespace llvm {
 
     static LaneBitmask getNone() { return LaneBitmask(0); }
     static LaneBitmask getAll()  { return ~LaneBitmask(0); }
+    static LaneBitmask getLane(unsigned Lane) {
+      return LaneBitmask(Type(1) << Lane);
+    }
 
   private:
     Type Mask = 0;
diff --git a/utils/TableGen/CodeGenRegisters.cpp b/utils/TableGen/CodeGenRegisters.cpp
index d4a21a986c5..6399fb5ec1d 100644
--- a/utils/TableGen/CodeGenRegisters.cpp
+++ b/utils/TableGen/CodeGenRegisters.cpp
@@ -1268,12 +1268,12 @@ void CodeGenRegBank::computeSubRegLaneMasks() {
   CoveringLanes = LaneBitmask::getAll();
   for (auto &Idx : SubRegIndices) {
     if (Idx.getComposites().empty()) {
-      if (Bit > 32) {
+      if (Bit > LaneBitmask::BitWidth) {
         PrintFatalError(
           Twine("Ran out of lanemask bits to represent subregister ")
           + Idx.getName());
       }
-      Idx.LaneMask = LaneBitmask(1 << Bit);
+      Idx.LaneMask = LaneBitmask::getLane(Bit);
       ++Bit;
     } else {
       Idx.LaneMask = LaneBitmask::getNone();
@@ -1298,9 +1298,9 @@ void CodeGenRegBank::computeSubRegLaneMasks() {
       static_assert(sizeof(Idx.LaneMask.getAsInteger()) == 4,
                     "Change Log2_32 to a proper one");
       unsigned DstBit = Log2_32(Idx.LaneMask.getAsInteger());
-      assert(Idx.LaneMask == LaneBitmask(1 << DstBit) &&
+      assert(Idx.LaneMask == LaneBitmask::getLane(DstBit) &&
              "Must be a leaf subregister");
-      MaskRolPair MaskRol = { LaneBitmask(1), (uint8_t)DstBit };
+      MaskRolPair MaskRol = { LaneBitmask::getLane(0), (uint8_t)DstBit };
       LaneTransforms.push_back(MaskRol);
     } else {
       // Go through all leaf subregisters and find the ones that compose with
@@ -1314,7 +1314,7 @@ void CodeGenRegBank::computeSubRegLaneMasks() {
           continue;
         // Replicate the behaviour from the lane mask generation loop above.
         unsigned SrcBit = NextBit;
-        LaneBitmask SrcMask = LaneBitmask(1 << SrcBit);
+        LaneBitmask SrcMask = LaneBitmask::getLane(SrcBit);
         if (NextBit < LaneBitmask::BitWidth-1)
           ++NextBit;
         assert(Idx2.LaneMask == SrcMask);
@@ -1386,7 +1386,7 @@ void CodeGenRegBank::computeSubRegLaneMasks() {
     // For classes without any subregisters set LaneMask to 1 instead of 0.
     // This makes it easier for client code to handle classes uniformly.
     if (LaneMask.none())
-      LaneMask = LaneBitmask(1);
+      LaneMask = LaneBitmask::getLane(0);
 
     RegClass.LaneMask = LaneMask;
   }
-- 
2.40.0