[PATCH] D84042: [AArch64][SVE] Don't align the last SVE callee save.

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen updated this revision to Diff 280495.
sdesmalen retitled this revision from "[AArch64][SVE] Fix alignment of last predicate callee save" to "[AArch64][SVE] Don't align the last SVE callee save.".
sdesmalen edited the summary of this revision.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D84042/new/

https://reviews.llvm.org/D84042

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
@@ -573,7 +573,7 @@
 # CHECK-NEXT:       stack-id: sve-vec, callee-saved-register: '$z23',
 # CHECK:        - { id: 8, name: '', type: spill-slot, offset: -34, size: 2, alignment: 2,
 # CHECK-NEXT:       stack-id: sve-vec, callee-saved-register: '$p4',
-# CHECK:        - { id: 9, name: '', type: spill-slot, offset: -48, size: 2, alignment: 16,
+# CHECK:        - { id: 9, name: '', type: spill-slot, offset: -36, size: 2, alignment: 2,
 # CHECK-NEXT:       stack-id: sve-vec, callee-saved-register: '$p15',
 # CHECK:        - { id: 10, name: '', type: spill-slot, offset: -16, size: 8, alignment: 16,
 # CHECK-NEXT:       stack-id: default, callee-saved-register: '$fp',
Index: llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1192,7 +1192,7 @@
 
   // Process the SVE callee-saves to determine what space needs to be
   // allocated.
-  if (AFI->getSVECalleeSavedStackSize()) {
+  if (int64_t CalleeSavedSize = AFI->getSVECalleeSavedStackSize()) {
     // Find callee save instructions in frame.
     CalleeSavesBegin = MBBI;
     assert(IsSVECalleeSave(CalleeSavesBegin) && "Unexpected instruction");
@@ -1200,11 +1200,7 @@
       ++MBBI;
     CalleeSavesEnd = MBBI;
 
-    int64_t OffsetToFirstCalleeSaveFromSP =
-        MFI.getObjectOffset(AFI->getMaxSVECSFrameIndex());
-    StackOffset OffsetToCalleeSavesFromSP =
-        StackOffset(OffsetToFirstCalleeSaveFromSP, MVT::nxv1i8) + SVEStackSize;
-    AllocateBefore -= OffsetToCalleeSavesFromSP;
+    AllocateBefore = {CalleeSavedSize, MVT::nxv1i8};
     AllocateAfter = SVEStackSize - AllocateBefore;
   }
 
@@ -1582,7 +1578,7 @@
   // deallocated.
   StackOffset DeallocateBefore = {}, DeallocateAfter = SVEStackSize;
   MachineBasicBlock::iterator RestoreBegin = LastPopI, RestoreEnd = LastPopI;
-  if (AFI->getSVECalleeSavedStackSize()) {
+  if (int64_t CalleeSavedSize = AFI->getSVECalleeSavedStackSize()) {
     RestoreBegin = std::prev(RestoreEnd);;
     while (IsSVECalleeSave(RestoreBegin) &&
            RestoreBegin != MBB.begin())
@@ -1592,12 +1588,9 @@
     assert(IsSVECalleeSave(RestoreBegin) &&
            IsSVECalleeSave(std::prev(RestoreEnd)) && "Unexpected instruction");
 
-    int64_t OffsetToFirstCalleeSaveFromSP =
-        MFI.getObjectOffset(AFI->getMaxSVECSFrameIndex());
-    StackOffset OffsetToCalleeSavesFromSP =
-        StackOffset(OffsetToFirstCalleeSaveFromSP, MVT::nxv1i8) + SVEStackSize;
-    DeallocateBefore = OffsetToCalleeSavesFromSP;
-    DeallocateAfter = SVEStackSize - DeallocateBefore;
+    StackOffset CalleeSavedSizeAsOffset = {CalleeSavedSize, MVT::nxv1i8};
+    DeallocateBefore = SVEStackSize - CalleeSavedSizeAsOffset;
+    DeallocateAfter = CalleeSavedSizeAsOffset;
   }
 
   // Deallocate the SVE area.
@@ -2611,9 +2604,6 @@
 
   // Then process all callee saved slots.
   if (getSVECalleeSaveSlotRange(MFI, MinCSFrameIndex, MaxCSFrameIndex)) {
-    // Make sure to align the last callee save slot.
-    MFI.setObjectAlignment(MaxCSFrameIndex, Align(16));
-
     // Assign offsets to the callee save slots.
     for (int I = MinCSFrameIndex; I <= MaxCSFrameIndex; ++I) {
       Offset += MFI.getObjectSize(I);
@@ -2623,6 +2613,9 @@
     }
   }
 
+  // Ensure that the Callee-save area is aligned to 16bytes.
+  Offset = alignTo(Offset, Align(16U));
+
   // Create a buffer of SVE objects to allocate and sort it.
   SmallVector<int, 8> ObjectsToAllocate;
   for (int I = 0, E = MFI.getObjectIndexEnd(); I != E; ++I) {


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D84042.280495.patch
Type: text/x-patch
Size: 3829 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200724/3dfe3b16/attachment.bin>