Enforce StackID definition in PEI

There are various places in LLVM where the definition of StackID is not
properly honoured, for example in PEI where objects with a StackID > 0 are
allocated on the default stack (StackID0). This patch enforces that PEI
only considers allocating objects to StackID 0.

Reviewers: arsenm, thegameg, MatzeB

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D60062

llvm-svn: 357460

1 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/MachineFrameInfo.cpp b/llvm/lib/CodeGen/MachineFrameInfo.cpp
index d75ba83..e8a3dda8 100644
--- a/llvm/lib/CodeGen/MachineFrameInfo.cpp
+++ b/llvm/lib/CodeGen/MachineFrameInfo.cpp
@@ -56,7 +56,8 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
                                 !IsSpillSlot, StackID));
   int Index = (int)Objects.size() - NumFixedObjects - 1;
   assert(Index >= 0 && "Bad frame index!");
-  ensureMaxAlignment(Alignment);
+  if (StackID == 0)
+    ensureMaxAlignment(Alignment);
   return Index;
 }
 
@@ -141,11 +142,15 @@ unsigned MachineFrameInfo::estimateStackSize(const MachineFunction &MF) const {
   // should keep in mind that there's tight coupling between the two.
 
   for (int i = getObjectIndexBegin(); i != 0; ++i) {
+    // Only estimate stack size of default stack.
+    if (getStackID(i))
+      continue;
     int FixedOff = -getObjectOffset(i);
     if (FixedOff > Offset) Offset = FixedOff;
   }
   for (unsigned i = 0, e = getObjectIndexEnd(); i != e; ++i) {
-    if (isDeadObjectIndex(i))
+    // Only estimate stack size of live objects on default stack.
+    if (isDeadObjectIndex(i) || getStackID(i))
       continue;
     Offset += getObjectSize(i);
     unsigned Align = getObjectAlignment(i);