[PATCH] D84539: [AArch64][SVE] Fix epilogue for SVE when the stack is realigned.

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen created this revision.
sdesmalen added reviewers: paulwalker-arm, efriedma.
Herald added subscribers: danielkiss, psnobl, hiraditya, kristof.beyls, tschuett.
Herald added a reviewer: rengolin.
Herald added a project: LLVM.

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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84539

Files:
  llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
  llvm/test/CodeGen/AArch64/framelayout-sve.mir


Index: llvm/test/CodeGen/AArch64/framelayout-sve.mir
===================================================================
--- llvm/test/CodeGen/AArch64/framelayout-sve.mir
+++ llvm/test/CodeGen/AArch64/framelayout-sve.mir
@@ -500,7 +500,7 @@
 # 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
Index: llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1603,12 +1603,13 @@
   // 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


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