[COFF, ARM64] Implement support for SEH extensions __try/__except/__finally

Summary:
This patch supports MS SEH extensions __try/__except/__finally. The intrinsics localescape and localrecover are responsible for communicating escaped static allocas from the try block to the handler.

We need to preserve frame pointers for SEH. So we create a new function/property HasLocalEscape.

Reviewers: rnk, compnerd, mstorsjo, TomTan, efriedma, ssijaric

Reviewed By: rnk, efriedma

Subscribers: smeenai, jrmuizel, alex, majnemer, ssijaric, ehsan, dmajor, kristina, javed.absar, kristof.beyls, chrib, llvm-commits

Differential Revision: https://reviews.llvm.org/D53540

llvm-svn: 351370

2 files changed, 16 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
index cf8e8c69bc2..92df09b7d6a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -545,15 +545,17 @@ void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
       OS.AddComment(Comment);
   };
 
-  // Emit a label assignment with the SEH frame offset so we can use it for
-  // llvm.eh.recoverfp.
-  StringRef FLinkageName =
-      GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
-  MCSymbol *ParentFrameOffset =
-      Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
-  const MCExpr *MCOffset =
-      MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx);
-  Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset);
+  if (!isAArch64) {
+    // Emit a label assignment with the SEH frame offset so we can use it for
+    // llvm.eh.recoverfp.
+    StringRef FLinkageName =
+        GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
+    MCSymbol *ParentFrameOffset =
+        Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
+    const MCExpr *MCOffset =
+        MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx);
+    Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset);
+  }
 
   // Use the assembler to compute the number of table entries through label
   // difference and division.
@@ -937,6 +939,9 @@ void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
   if (FI != INT_MAX) {
     const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
     unsigned UnusedReg;
+    // FIXME: getFrameIndexReference needs to match the behavior of
+    // AArch64RegisterInfo::hasBasePointer in which one of the scenarios where
+    // SP is used is if frame size >= 256.
     Offset = TFI->getFrameIndexReference(*Asm->MF, FI, UnusedReg);
   }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index e887af4ca58..3390703c7ba 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6183,6 +6183,8 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
           .addFrameIndex(FI);
     }
 
+    MF.setHasLocalEscape(true);
+
     return nullptr;
   }