X86: Make @llvm.frameaddress work correctly with Windows unwind codes

Simply loading or storing the frame pointer is not sufficient for
Windows targets.  Instead, create a synthetic frame object that we will
lower later.  References to this synthetic object will be replaced with
the correct reference to the frame address.

llvm-svn: 228748

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index adeb46df8d5..d049c02da77 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1242,6 +1242,9 @@ int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF,
       NumBytes = FrameSize - CSSize;
     }
     uint64_t SEHFrameOffset = calculateSetFPREG(NumBytes);
+    if (FI && FI == X86FI->getFAIndex())
+      return -SEHFrameOffset;
+
     // FPDelta is the offset from the "traditional" FP location of the old base
     // pointer followed by return address and the location required by the
     // restricted Win64 prologue.