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, 25 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 920a915552a..67834c8c352 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -661,10 +661,13 @@ computeFreeStackSlots(MachineFrameInfo &MFI, bool StackGrowsDown,
   SmallVector<int, 16> AllocatedFrameSlots;
   // Add fixed objects.
   for (int i = MFI.getObjectIndexBegin(); i != 0; ++i)
-    AllocatedFrameSlots.push_back(i);
+    // StackSlot scavenging is only implemented for the default stack.
+    if (MFI.getStackID(i) == 0)
+      AllocatedFrameSlots.push_back(i);
   // Add callee-save objects.
   for (int i = MinCSFrameIndex; i <= (int)MaxCSFrameIndex; ++i)
-    AllocatedFrameSlots.push_back(i);
+    if (MFI.getStackID(i) == 0)
+      AllocatedFrameSlots.push_back(i);
 
   for (int i : AllocatedFrameSlots) {
     // These are converted from int64_t, but they should always fit in int
@@ -786,11 +789,21 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
   // Skew to be applied to alignment.
   unsigned Skew = TFI.getStackAlignmentSkew(MF);
 
+#ifdef EXPENSIVE_CHECKS
+  for (unsigned i = 0, e = MFI.getObjectIndexEnd(); i != e; ++i)
+    if (!MFI.isDeadObjectIndex(i) && MFI.getStackID(i) == 0)
+      assert(MFI.getObjectAlignment(i) <= MFI.getMaxAlignment() &&
+             "MaxAlignment is invalid");
+#endif
+
   // If there are fixed sized objects that are preallocated in the local area,
   // non-fixed objects can't be allocated right at the start of local area.
   // Adjust 'Offset' to point to the end of last fixed sized preallocated
   // object.
   for (int i = MFI.getObjectIndexBegin(); i != 0; ++i) {
+    if (MFI.getStackID(i)) // Only allocate objects on the default stack.
+      continue;
+
     int64_t FixedOff;
     if (StackGrowsDown) {
       // The maximum distance from the stack pointer is at lower address of
@@ -809,6 +822,9 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
   // callee saved registers.
   if (StackGrowsDown) {
     for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
+      if (MFI.getStackID(i)) // Only allocate objects on the default stack.
+        continue;
+
       // If the stack grows down, we need to add the size to find the lowest
       // address of the object.
       Offset += MFI.getObjectSize(i);
@@ -823,6 +839,9 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
   } else if (MaxCSFrameIndex >= MinCSFrameIndex) {
     // Be careful about underflow in comparisons agains MinCSFrameIndex.
     for (unsigned i = MaxCSFrameIndex; i != MinCSFrameIndex - 1; --i) {
+      if (MFI.getStackID(i)) // Only allocate objects on the default stack.
+        continue;
+
       if (MFI.isDeadObjectIndex(i))
         continue;
 
@@ -913,6 +932,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
       if (MFI.getStackProtectorIndex() == (int)i ||
           EHRegNodeFrameIndex == (int)i)
         continue;
+      if (MFI.getStackID(i)) // Only allocate objects on the default stack.
+        continue;
 
       switch (MFI.getObjectSSPLayout(i)) {
       case MachineFrameInfo::SSPLK_None:
@@ -956,6 +977,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
       continue;
     if (ProtectedObjs.count(i))
       continue;
+    if (MFI.getStackID(i)) // Only allocate objects on the default stack.
+      continue;
 
     // Add the objects that we need to allocate to our working set.
     ObjectsToAllocate.push_back(i);