Add parentheses around arithmetic in operand of '|' in llvm-dwp.cpp.

[congliu]

Summary

Add the parenthese to make it able to build.

[bkramer]

I think this is the wrong solution. Per http://www.dwarfstd.org/ShowIssue.php?issue=140421.1

2.  Calculate a secondary hash H' = (((S >> 32) & MASK(k)) | 1).
[...]
4.  Let H = (H + H') modulo M. Repeat at Step 3.

So the OR has to happen before the ADD.

[congliu]

• Address review comment.

[bkramer]

LGTM, will commit it for you.

[dblaikie]

Thanks all! Which compiler flagged this? Wonder if/why Clang didn't flag it
for me?

llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp

static void writeIndex(MCStreamer &Out, MCSection *Section,
   std::vector<unsigned> Buckets(NextPowerOf2(3 * IndexEntries.size() / 2));
   uint64_t Mask = Buckets.size() - 1;
   for (size_t i = 0; i != IndexEntries.size(); ++i) {
     auto S = IndexEntries[i].Signature;
     auto H = S & Mask;
     while (Buckets[H]) {
       assert(S != IndexEntries[Buckets[H] - 1].Signature &&
              "Duplicate type unit");
-      H = (H + ((S >> 32) & Mask) | 1) % Buckets.size();
+      H = (H + (((S >> 32) & Mask) | 1)) % Buckets.size();
     }
     Buckets[H] = i + 1;
   }
 
   Out.SwitchSection(Section);
   Out.EmitIntValue(2, 4);                   // Version
   Out.EmitIntValue(Columns, 4);             // Columns
   Out.EmitIntValue(IndexEntries.size(), 4); // Num Units