[llvm] r272426 - [CodeGen] Fix PrologEpilogInserter to avoid duplicate allocation of SEH structs

[Etienne Bergeron via llvm-commits]

Author: etienneb
Date: Fri Jun 10 15:24:38 2016
New Revision: 272426

URL: http://llvm.org/viewvc/llvm-project?rev=272426&view=rev
Log:
[CodeGen] Fix PrologEpilogInserter to avoid duplicate allocation of SEH structs

Summary:
When stack-protection is activated and WinEH exceptions is used, 
the EHRegNode (exception handling registration) is allocated twice on the stack.

This was not breaking anything except loosing space on the stack.

```
D:\src\llvm\examples>llc exc2.ll  -debug-only=pei
alloc FI(0) at SP[-24]
alloc FI(1) at SP[-48]   <<-- Allocated
alloc FI(1) at SP[-72]   <<-- Allocated twice!?
alloc FI(2) at SP[-76]
alloc FI(4) at SP[-80]
alloc FI(3) at SP[-84]
```

Reviewers: rnk, majnemer

Subscribers: chrisha, llvm-commits

Differential Revision: http://reviews.llvm.org/D21188

Modified:
    llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp

Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp?rev=272426&r1=272425&r2=272426&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp (original)
+++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp Fri Jun 10 15:24:38 2016
@@ -815,6 +815,11 @@ void PEI::calculateFrameObjectOffsets(Ma
     MaxAlign = std::max(Align, MaxAlign);
   }
 
+  // Retrieve the Exception Handler registration node.
+  int EHRegNodeFrameIndex = INT_MAX;
+  if (const WinEHFuncInfo *FuncInfo = Fn.getWinEHFuncInfo())
+    EHRegNodeFrameIndex = FuncInfo->EHRegNodeFrameIndex;
+
   // Make sure that the stack protector comes before the local variables on the
   // stack.
   SmallSet<int, 16> ProtectedObjs;
@@ -837,7 +842,8 @@ void PEI::calculateFrameObjectOffsets(Ma
         continue;
       if (MFI->isDeadObjectIndex(i))
         continue;
-      if (MFI->getStackProtectorIndex() == (int)i)
+      if (MFI->getStackProtectorIndex() == (int)i ||
+          EHRegNodeFrameIndex == (int)i)
         continue;
 
       switch (SP->getSSPLayout(MFI->getObjectAllocation(i))) {
@@ -866,10 +872,6 @@ void PEI::calculateFrameObjectOffsets(Ma
 
   SmallVector<int, 8> ObjectsToAllocate;
 
-  int EHRegNodeFrameIndex = INT_MAX;
-  if (const WinEHFuncInfo *FuncInfo = Fn.getWinEHFuncInfo())
-    EHRegNodeFrameIndex = FuncInfo->EHRegNodeFrameIndex;
-
   // Then prepare to 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) {
@@ -882,9 +884,8 @@ void PEI::calculateFrameObjectOffsets(Ma
       continue;
     if (MFI->isDeadObjectIndex(i))
       continue;
-    if (MFI->getStackProtectorIndex() == (int)i)
-      continue;
-    if (EHRegNodeFrameIndex == (int)i)
+    if (MFI->getStackProtectorIndex() == (int)i ||
+        EHRegNodeFrameIndex == (int)i)
       continue;
     if (ProtectedObjs.count(i))
       continue;