[PATCH] D79779: [CodeGen] Make CreateStackTemporary work for scalable vectors

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
david-arm added reviewers: fpetrogalli, sdesmalen, ctetreau.
Herald added subscribers: llvm-commits, hiraditya, kristof.beyls.
Herald added a reviewer: rengolin.
Herald added a project: LLVM.

In CreateStackTemporary we were promoting alignments beyond the
stack alignment, which I have fixed in this patch. In addition, we
need to set the stack id explicitly for scalable vectors so that
we allocate the correct amount of stack using vscale.

I added a test to

  CodeGen/AArch64/sve-insert-element.ll

that tries to insert an element into an illegal scalable vector
type that involves creating temporary stack objects.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D79779

Files:
  llvm/include/llvm/CodeGen/SelectionDAG.h
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/test/CodeGen/AArch64/sve-insert-element.ll


Index: llvm/test/CodeGen/AArch64/sve-insert-element.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-insert-element.ll
+++ llvm/test/CodeGen/AArch64/sve-insert-element.ll
@@ -133,3 +133,13 @@
   %b = insertelement <vscale x 16 x i8> undef, i8 %a, i32 0
   ret <vscale x 16 x i8> %b
 }
+
+; TODO: The code generated for this function is still incorrect, hence there
+; is only a single CHECK line to ensure we use 'addvl' for scalable stack
+; objects.
+define <vscale x 32 x i8> @test_lanex_32xi8(<vscale x 32 x i8> %a, i32 %x) {
+; CHECK-LABEL: test_lanex_32xi8
+; CHECK:       addvl sp, sp, #-2
+  %b = insertelement <vscale x 32 x i8> %a, i8 30, i32 %x
+  ret <vscale x 32 x i8> %b
+}
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -38,6 +38,7 @@
 #include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
 #include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/SelectionDAGTargetInfo.h"
+#include "llvm/CodeGen/TargetFrameLowering.h"
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
@@ -1995,28 +1996,39 @@
                   MachinePointerInfo(VD));
 }
 
-SDValue SelectionDAG::CreateStackTemporary(EVT VT, unsigned minAlign) {
-  MachineFrameInfo &MFI = getMachineFunction().getFrameInfo();
-  unsigned ByteSize = VT.getStoreSize();
-  Type *Ty = VT.getTypeForEVT(*getContext());
-  unsigned StackAlign =
-      std::max((unsigned)getDataLayout().getPrefTypeAlignment(Ty), minAlign);
+SDValue SelectionDAG::CreateStackTemporary(TypeSize Bytes, Align Alignment) {
+  // Scalable vectors need a special StackID to distinguish them from other
+  // (fixed size) stack objects.
+  unsigned StackId = 0;
+  if (Bytes.isScalable()) {
+    const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
+    StackId = TFI->getStackIDForScalableVectors();
+  }
 
-  int FrameIdx = MFI.CreateStackObject(ByteSize, StackAlign, false);
+  MachineFrameInfo &MFI = MF->getFrameInfo();
+  int FrameIdx =
+      MFI.CreateStackObject(Bytes, Alignment, false, nullptr, StackId);
   return getFrameIndex(FrameIdx, TLI->getFrameIndexTy(getDataLayout()));
 }
 
+SDValue SelectionDAG::CreateStackTemporary(EVT VT, unsigned minAlign) {
+  const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
+  Type *Ty = VT.getTypeForEVT(*getContext());
+  const Align PrefAlign = getDataLayout().getPrefTypeAlign(Ty);
+  const Align StackAlign = TFI->getStackAlign();
+  const Align Alignment =
+      std::max(std::min(PrefAlign, StackAlign), Align(minAlign));
+  return CreateStackTemporary(VT.getStoreSize(), Alignment);
+}
+
 SDValue SelectionDAG::CreateStackTemporary(EVT VT1, EVT VT2) {
-  unsigned Bytes = std::max(VT1.getStoreSize(), VT2.getStoreSize());
+  const TypeSize Bytes = std::max(VT1.getStoreSize(), VT2.getStoreSize());
   Type *Ty1 = VT1.getTypeForEVT(*getContext());
   Type *Ty2 = VT2.getTypeForEVT(*getContext());
-  const DataLayout &DL = getDataLayout();
-  unsigned Align =
-      std::max(DL.getPrefTypeAlignment(Ty1), DL.getPrefTypeAlignment(Ty2));
-
-  MachineFrameInfo &MFI = getMachineFunction().getFrameInfo();
-  int FrameIdx = MFI.CreateStackObject(Bytes, Align, false);
-  return getFrameIndex(FrameIdx, TLI->getFrameIndexTy(getDataLayout()));
+  const DataLayout DL = getDataLayout();
+  Align Alignment =
+      std::max(DL.getPrefTypeAlign(Ty1), DL.getPrefTypeAlign(Ty2));
+  return CreateStackTemporary(Bytes, Alignment);
 }
 
 SDValue SelectionDAG::FoldSetCC(EVT VT, SDValue N1, SDValue N2,
Index: llvm/include/llvm/CodeGen/SelectionDAG.h
===================================================================
--- llvm/include/llvm/CodeGen/SelectionDAG.h
+++ llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -1595,6 +1595,9 @@
 
   void dump() const;
 
+  /// Create a stack temporary based on the size in bytes and the alignment
+  SDValue CreateStackTemporary(TypeSize Bytes, Align Alignment);
+
   /// Create a stack temporary, suitable for holding the specified value type.
   /// If minAlign is specified, the slot size will have at least that alignment.
   SDValue CreateStackTemporary(EVT VT, unsigned minAlign = 1);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D79779.263407.patch
Type: text/x-patch
Size: 4386 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200512/b633144f/attachment.bin>