Generate native unwind info on Win64

This patch enables LLVM to emit Win64-native unwind info rather than
DWARF CFI.  It handles all corner cases (I hope), including stack
realignment.

Because the unwind info is not flexible enough to describe stack frames
with a gap of unknown size in the middle, such as the one caused by
stack realignment, I modified register spilling code to place all spills
into the fixed frame slots, so that they can be accessed relative to the
frame pointer.

Patch by Vadim Chugunov!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D4081

llvm-svn: 211399

1 files changed, 28 insertions, 17 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index eb3d71fef5c..6138aef4adc 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -457,7 +457,7 @@ unsigned MachineFunction::addLiveIn(unsigned PReg,
 /// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
 /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
 /// normal 'L' label is returned.
-MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx, 
+MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
                                         bool isLinkerPrivate) const {
   const DataLayout *DL = getTarget().getDataLayout();
   assert(JumpTableInfo && "No jump tables");
@@ -530,10 +530,9 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
 ///
 int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
                                              unsigned Alignment) {
-  Alignment =
-    clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
-                          !RealignOption,
-                        Alignment, getFrameLowering()->getStackAlignment()); 
+  Alignment = clampStackAlignment(
+      !getFrameLowering()->isStackRealignable() || !RealignOption, Alignment,
+      getFrameLowering()->getStackAlignment());
   CreateStackObject(Size, Alignment, true);
   int Index = (int)Objects.size() - NumFixedObjects - 1;
   ensureMaxAlignment(Alignment);
@@ -548,10 +547,9 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
 int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment,
                                                 const AllocaInst *Alloca) {
   HasVarSizedObjects = true;
-  Alignment =
-    clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
-                          !RealignOption,
-                        Alignment, getFrameLowering()->getStackAlignment()); 
+  Alignment = clampStackAlignment(
+      !getFrameLowering()->isStackRealignable() || !RealignOption, Alignment,
+      getFrameLowering()->getStackAlignment());
   Objects.push_back(StackObject(0, Alignment, 0, false, false, Alloca));
   ensureMaxAlignment(Alignment);
   return (int)Objects.size()-NumFixedObjects-1;
@@ -571,16 +569,30 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
   // object is 16-byte aligned.
   unsigned StackAlign = getFrameLowering()->getStackAlignment();
   unsigned Align = MinAlign(SPOffset, StackAlign);
-  Align =
-    clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
-                          !RealignOption,
-                        Align, getFrameLowering()->getStackAlignment()); 
+  Align = clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
+                                  !RealignOption,
+                              Align, getFrameLowering()->getStackAlignment());
   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
                                               /*isSS*/   false,
                                               /*Alloca*/ nullptr));
   return -++NumFixedObjects;
 }
 
+/// CreateFixedSpillStackObject - Create a spill slot at a fixed location
+/// on the stack.  Returns an index with a negative value.
+int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
+                                                  int64_t SPOffset) {
+  unsigned StackAlign = getFrameLowering()->getStackAlignment();
+  unsigned Align = MinAlign(SPOffset, StackAlign);
+  Align = clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
+                                  !RealignOption,
+                              Align, getFrameLowering()->getStackAlignment());
+  Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset,
+                                              /*Immutable*/ true,
+                                              /*isSS*/ true,
+                                              /*Alloca*/ nullptr));
+  return -++NumFixedObjects;
+}
 
 BitVector
 MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
@@ -849,11 +861,10 @@ static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
   if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
       isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
     return false;
-  
+
   // For now, only support constants with the same size.
   uint64_t StoreSize = TD->getTypeStoreSize(A->getType());
-  if (StoreSize != TD->getTypeStoreSize(B->getType()) || 
-      StoreSize > 128)
+  if (StoreSize != TD->getTypeStoreSize(B->getType()) || StoreSize > 128)
     return false;
 
   Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
@@ -882,7 +893,7 @@ static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
 /// an existing one.  User must specify the log2 of the minimum required
 /// alignment for the object.
 ///
-unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C, 
+unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
                                                    unsigned Alignment) {
   assert(Alignment && "Alignment must be specified!");
   if (Alignment > PoolAlignment) PoolAlignment = Alignment;