[PATCH] D15393: [X86] Order the local stack symbols to improve code size and locality.

[Zia Ansari via llvm-commits]

zansari added a comment.

Hi Joerg,

Unless I'm missing something, this shouldn't affect stack protection in any way. The algorithm only works within the scope of this:

  // Then assign frame offsets to stack objects that are not used to spill
  // callee saved registers.
  for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
    if (MFI->isObjectPreAllocated(i) &&
        MFI->getUseLocalStackAllocationBlock())
      continue;
    if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
      continue;
    if (RS && RS->isScavengingFrameIndex((int)i))
      continue;
    if (MFI->isDeadObjectIndex(i))
      continue;
    if (MFI->getStackProtectorIndex() == (int)i)
      continue;
    if (ProtectedObjs.count(i))
      continue;
  
    AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign, Skew);
  }

and reorders only these objects per whatever custom algorithm. The stack protection (and any other "special" conditions that need allocation) are handled prior to this allocation walk.. Please correct me, if I'm wrong.


http://reviews.llvm.org/D15393