[AArch64] Fix mismatch in prologue and epilogue for funclets on Windows

The generated code for a funclet can have an add to sp in the epilogue
for which there is no corresponding sub in the prologue.

This patch removes the early return from emitPrologue that was
preventing the sub to sp, and instead conditionalizes the appropriate
parts of the rest of the function.

Fixes https://bugs.llvm.org/show_bug.cgi?id=45345

Differential Revision: https://reviews.llvm.org/D77015

(cherry picked from commit 522b4c4b88a5606b0074926e8658e7fede97c230)

1 files changed, 20 insertions, 28 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index ea3e800a1ad..1a84cdd49f1 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -993,32 +993,8 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
     ++MBBI;
   }
 
-  // The code below is not applicable to funclets. We have emitted all the SEH
-  // opcodes that we needed to emit.  The FP and BP belong to the containing
-  // function.
-  if (IsFunclet) {
-    if (NeedsWinCFI) {
-      HasWinCFI = true;
-      BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_PrologEnd))
-          .setMIFlag(MachineInstr::FrameSetup);
-    }
-
-    // SEH funclets are passed the frame pointer in X1.  If the parent
-    // function uses the base register, then the base register is used
-    // directly, and is not retrieved from X1.
-    if (F.hasPersonalityFn()) {
-      EHPersonality Per = classifyEHPersonality(F.getPersonalityFn());
-      if (isAsynchronousEHPersonality(Per)) {
-        BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), AArch64::FP)
-            .addReg(AArch64::X1).setMIFlag(MachineInstr::FrameSetup);
-        MBB.addLiveIn(AArch64::X1);
-      }
-    }
-
-    return;
-  }
-
-  if (HasFP) {
+  // For funclets the FP belongs to the containing function.
+  if (!IsFunclet && HasFP) {
     // Only set up FP if we actually need to.
     int64_t FPOffset = isTargetDarwin(MF) ? (AFI->getCalleeSavedStackSize() - 16) : 0;
 
@@ -1161,7 +1137,9 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
 
   // Allocate space for the rest of the frame.
   if (NumBytes) {
-    const bool NeedsRealignment = RegInfo->needsStackRealignment(MF);
+    // Alignment is required for the parent frame, not the funclet
+    const bool NeedsRealignment =
+        !IsFunclet && RegInfo->needsStackRealignment(MF);
     unsigned scratchSPReg = AArch64::SP;
 
     if (NeedsRealignment) {
@@ -1215,7 +1193,8 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
   // FIXME: Clarify FrameSetup flags here.
   // Note: Use emitFrameOffset() like above for FP if the FrameSetup flag is
   // needed.
-  if (RegInfo->hasBasePointer(MF)) {
+  // For funclets the BP belongs to the containing function.
+  if (!IsFunclet && RegInfo->hasBasePointer(MF)) {
     TII->copyPhysReg(MBB, MBBI, DL, RegInfo->getBaseRegister(), AArch64::SP,
                      false);
     if (NeedsWinCFI) {
@@ -1232,6 +1211,19 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
         .setMIFlag(MachineInstr::FrameSetup);
   }
 
+  // SEH funclets are passed the frame pointer in X1.  If the parent
+  // function uses the base register, then the base register is used
+  // directly, and is not retrieved from X1.
+  if (IsFunclet && F.hasPersonalityFn()) {
+    EHPersonality Per = classifyEHPersonality(F.getPersonalityFn());
+    if (isAsynchronousEHPersonality(Per)) {
+      BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), AArch64::FP)
+          .addReg(AArch64::X1)
+          .setMIFlag(MachineInstr::FrameSetup);
+      MBB.addLiveIn(AArch64::X1);
+    }
+  }
+
   if (needsFrameMoves) {
     const DataLayout &TD = MF.getDataLayout();
     const int StackGrowth = isTargetDarwin(MF)