From cda2eb3ad2bbe923e74d6eb083af196a0622d800 Mon Sep 17 00:00:00 2001
From: Sander de Smalen <sander.desmalen@arm.com>
Date: Tue, 28 Jul 2020 12:11:09 +0100
Subject: [PATCH] [AArch64][SVE] Fix epilogue for SVE when the stack is
 realigned.

While deallocating the stackframe, the offset used to reload the
callee-saved registers was not pointing to the SVE callee-saves,
but rather to the whole SVE area.

   +--------------+
   | GRP callee   |
   |     saves    |
   +--------------+ <- FP
   | SVE callee   |
   |     saves    |
   +--------------+ <- Should restore SVE callee saves from here
   |  SVE Spills  |
   |  and Locals  |
   +--------------+ <- instead of from here.
   |              |
   :              :
   |              |
   +--------------+ <- SP

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D84539
---
 llvm/lib/Target/AArch64/AArch64FrameLowering.cpp | 9 +++++----
 llvm/test/CodeGen/AArch64/framelayout-sve.mir    | 2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 1b49c692f293..4789a9f02937 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1596,12 +1596,13 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
   // Deallocate the SVE area.
   if (SVEStackSize) {
     if (AFI->isStackRealigned()) {
-      if (AFI->getSVECalleeSavedStackSize())
-        // Set SP to start of SVE area, from which the callee-save reloads
-        // can be done. The code below will deallocate the stack space
+      if (int64_t CalleeSavedSize = AFI->getSVECalleeSavedStackSize())
+        // Set SP to start of SVE callee-save area from which they can
+        // be reloaded. The code below will deallocate the stack space
         // space by moving FP -> SP.
         emitFrameOffset(MBB, RestoreBegin, DL, AArch64::SP, AArch64::FP,
-                        -SVEStackSize, TII, MachineInstr::FrameDestroy);
+                        {-CalleeSavedSize, MVT::nxv1i8}, TII,
+                        MachineInstr::FrameDestroy);
     } else {
       if (AFI->getSVECalleeSavedStackSize()) {
         // Deallocate the non-SVE locals first before we can deallocate (and
diff --git a/llvm/test/CodeGen/AArch64/framelayout-sve.mir b/llvm/test/CodeGen/AArch64/framelayout-sve.mir
index 75a65a6ad522..668b243dd79e 100644
--- a/llvm/test/CodeGen/AArch64/framelayout-sve.mir
+++ b/llvm/test/CodeGen/AArch64/framelayout-sve.mir
@@ -500,7 +500,7 @@ body:             |
 # CHECK-NEXT: $[[TMP:x[0-9]+]] = frame-setup SUBXri $sp, 16, 0
 # CHECK-NEXT: $sp = ANDXri killed $[[TMP]]
 
-# CHECK:      $sp = frame-destroy ADDVL_XXI $fp, -19
+# CHECK:      $sp = frame-destroy ADDVL_XXI $fp, -18
 # CHECK-NEXT: $p15 = frame-destroy LDR_PXI $sp, 4
 # CHECK-NEXT: $p14 = frame-destroy LDR_PXI $sp, 5
 # CHECK:      $p5 = frame-destroy LDR_PXI $sp, 14