[MC] [Win64EH] Generate ARM64 packed unwind info with signed return addresses

Differential Revision: https://reviews.llvm.org/D135660

1 files changed, 19 insertions, 8 deletions

diff --git a/llvm/lib/MC/MCWin64EH.cpp b/llvm/lib/MC/MCWin64EH.cpp
index f39383e..d2afb9c 100644
--- a/llvm/lib/MC/MCWin64EH.cpp
+++ b/llvm/lib/MC/MCWin64EH.cpp
@@ -734,6 +734,7 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
   enum {
     Start,
     Start2,
+    Start3,
     IntRegs,
     FloatRegs,
     InputArgs,
@@ -742,6 +743,7 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
     End
   } Location = Start;
   bool StandaloneLR = false, FPLRPair = false;
+  bool PAC = false;
   int StackOffset = 0;
   int Nops = 0;
   // Iterate over the prolog and check that all opcodes exactly match
@@ -757,15 +759,21 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
         return false;
       Location = Start2;
       break;
-    case Win64EH::UOP_SaveR19R20X:
+    case Win64EH::UOP_PACSignReturnAddress:
       if (Location != Start2)
         return false;
+      PAC = true;
+      Location = Start3;
+      break;
+    case Win64EH::UOP_SaveR19R20X:
+      if (Location != Start2 && Location != Start3)
+        return false;
       Predecrement = Inst.Offset;
       RegI = 2;
       Location = IntRegs;
       break;
     case Win64EH::UOP_SaveRegX:
-      if (Location != Start2)
+      if (Location != Start2 && Location != Start3)
         return false;
       Predecrement = Inst.Offset;
       if (Inst.Register == 19)
@@ -828,7 +836,7 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
       Location = InputArgs;
       break;
     case Win64EH::UOP_SaveFRegPX:
-      if (Location != Start2 || Inst.Register != 8)
+      if ((Location != Start2 && Location != Start3) || Inst.Register != 8)
         return false;
       Predecrement = Inst.Offset;
       RegF = 2;
@@ -858,8 +866,9 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
       break;
     case Win64EH::UOP_AllocSmall:
     case Win64EH::UOP_AllocMedium:
-      if (Location != Start2 && Location != IntRegs && Location != FloatRegs &&
-          Location != InputArgs && Location != StackAdjust)
+      if (Location != Start2 && Location != Start3 && Location != IntRegs &&
+          Location != FloatRegs && Location != InputArgs &&
+          Location != StackAdjust)
         return false;
       // Can have either a single decrement, or a pair of decrements with
       // 4080 and another decrement.
@@ -874,8 +883,8 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
     case Win64EH::UOP_SaveFPLRX:
       // Not allowing FPLRX after StackAdjust; if a StackAdjust is used, it
       // should be followed by a FPLR instead.
-      if (Location != Start2 && Location != IntRegs && Location != FloatRegs &&
-          Location != InputArgs)
+      if (Location != Start2 && Location != Start3 && Location != IntRegs &&
+          Location != FloatRegs && Location != InputArgs)
         return false;
       StackOffset = Inst.Offset;
       Location = FrameRecord;
@@ -903,6 +912,8 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
     return false;
   if (Nops != 0 && Nops != 4)
     return false;
+  if (PAC && !FPLRPair)
+    return false;
   int H = Nops == 4;
   // There's an inconsistency regarding packed unwind info with homed
   // parameters; according to the documentation, the epilog shouldn't have
@@ -933,7 +944,7 @@ static bool tryARM64PackedUnwind(WinEH::FrameInfo *info, uint32_t FuncLength,
     RegF--; // Convert from actual number of registers, to value stored
   assert(FuncLength <= 0x7FF && "FuncLength should have been checked earlier");
   int Flag = 0x01; // Function segments not supported yet
-  int CR = FPLRPair ? 3 : StandaloneLR ? 1 : 0;
+  int CR = PAC ? 2 : FPLRPair ? 3 : StandaloneLR ? 1 : 0;
   info->PackedInfo |= Flag << 0;
   info->PackedInfo |= (FuncLength & 0x7FF) << 2;
   info->PackedInfo |= (RegF & 0x7) << 13;