[llvm] r248561 - ARM: address WoA division limitation

Saleem Abdulrasool via llvm-commits llvm-commits at lists.llvm.org
Thu Sep 24 22:15:47 PDT 2015


Author: compnerd
Date: Fri Sep 25 00:15:46 2015
New Revision: 248561

URL: http://llvm.org/viewvc/llvm-project?rev=248561&view=rev
Log:
ARM: address WoA division limitation

We now emit the compiler generated divide by zero check that was needed for the
MSVC routines.  We construct a psuedo-instruction for the DBZ check as the
operation requires splitting up the BB.  For the 64-bit operations, we need to
custom expand the node as we need to insert the DBZ check and then emit the
libcall to the appropriate name.  Because this is target specific, it seemed
better to reproduce the expansion operation from the target-agnostic type
legalization rather than sink this there to avoid the duplication.  The division
library calls now match MSVC semantically.

Added:
    llvm/trunk/test/CodeGen/ARM/Windows/division.ll
Modified:
    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
    llvm/trunk/lib/Target/ARM/ARMISelLowering.h
    llvm/trunk/lib/Target/ARM/ARMInstrInfo.td
    llvm/trunk/test/CodeGen/ARM/Windows/libcalls.ll

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=248561&r1=248560&r2=248561&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Fri Sep 25 00:15:46 2015
@@ -368,11 +368,6 @@ ARMTargetLowering::ARMTargetLowering(con
       { RTLIB::SINTTOFP_I64_F64, "__i64tod", CallingConv::ARM_AAPCS_VFP },
       { RTLIB::UINTTOFP_I64_F32, "__u64tos", CallingConv::ARM_AAPCS_VFP },
       { RTLIB::UINTTOFP_I64_F64, "__u64tod", CallingConv::ARM_AAPCS_VFP },
-
-      { RTLIB::SDIV_I32, "__rt_sdiv",   CallingConv::ARM_AAPCS_VFP },
-      { RTLIB::UDIV_I32, "__rt_udiv",   CallingConv::ARM_AAPCS_VFP },
-      { RTLIB::SDIV_I64, "__rt_sdiv64", CallingConv::ARM_AAPCS_VFP },
-      { RTLIB::UDIV_I64, "__rt_udiv64", CallingConv::ARM_AAPCS_VFP },
     };
 
     for (const auto &LC : LibraryCalls) {
@@ -743,6 +738,14 @@ ARMTargetLowering::ARMTargetLowering(con
     setOperationAction(ISD::UDIV,  MVT::i32, Expand);
   }
 
+  if (Subtarget->isTargetWindows() && !Subtarget->hasDivide()) {
+    setOperationAction(ISD::SDIV, MVT::i32, Custom);
+    setOperationAction(ISD::UDIV, MVT::i32, Custom);
+
+    setOperationAction(ISD::SDIV, MVT::i64, Custom);
+    setOperationAction(ISD::UDIV, MVT::i64, Custom);
+  }
+
   setOperationAction(ISD::SREM,  MVT::i32, Expand);
   setOperationAction(ISD::UREM,  MVT::i32, Expand);
   // Register based DivRem for AEABI (RTABI 4.2)
@@ -1119,6 +1122,7 @@ const char *ARMTargetLowering::getTarget
   case ARMISD::PRELOAD:       return "ARMISD::PRELOAD";
 
   case ARMISD::WIN__CHKSTK:   return "ARMISD:::WIN__CHKSTK";
+  case ARMISD::WIN__DBZCHK:   return "ARMISD::WIN__DBZCHK";
 
   case ARMISD::VCEQ:          return "ARMISD::VCEQ";
   case ARMISD::VCEQZ:         return "ARMISD::VCEQZ";
@@ -6645,6 +6649,85 @@ SDValue ARMTargetLowering::LowerFSINCOS(
                      LoadSin.getValue(0), LoadCos.getValue(0));
 }
 
+SDValue ARMTargetLowering::LowerWindowsDIVLibCall(SDValue Op, SelectionDAG &DAG,
+                                                  bool Signed,
+                                                  SDValue &Chain) const {
+  EVT VT = Op.getValueType();
+  assert((VT == MVT::i32 || VT == MVT::i64) &&
+         "unexpected type for custom lowering DIV");
+  SDLoc dl(Op);
+
+  const auto &DL = DAG.getDataLayout();
+  const auto &TLI = DAG.getTargetLoweringInfo();
+
+  const char *Name = nullptr;
+  if (Signed)
+    Name = (VT == MVT::i32) ? "__rt_sdiv" : "__rt_sdiv64";
+  else
+    Name = (VT == MVT::i32) ? "__rt_udiv" : "__rt_udiv64";
+
+  SDValue ES = DAG.getExternalSymbol(Name, TLI.getPointerTy(DL));
+
+  ARMTargetLowering::ArgListTy Args;
+
+  for (auto AI : {1, 0}) {
+    ArgListEntry Arg;
+    Arg.Node = Op.getOperand(AI);
+    Arg.Ty = Arg.Node.getValueType().getTypeForEVT(*DAG.getContext());
+    Args.push_back(Arg);
+  }
+
+  CallLoweringInfo CLI(DAG);
+  CLI.setDebugLoc(dl)
+    .setChain(Chain)
+    .setCallee(CallingConv::ARM_AAPCS_VFP, VT.getTypeForEVT(*DAG.getContext()),
+               ES, std::move(Args), 0);
+
+  return LowerCallTo(CLI).first;
+}
+
+SDValue ARMTargetLowering::LowerDIV_Windows(SDValue Op, SelectionDAG &DAG,
+                                            bool Signed) const {
+  EVT VT = Op.getValueType();
+  assert(VT == MVT::i32 && "unexpected type for custom lowering DIV");
+  SDLoc dl(Op);
+
+  SDValue DBZCHK = DAG.getNode(ARMISD::WIN__DBZCHK, dl, MVT::Other,
+                               DAG.getEntryNode(), Op.getOperand(1));
+
+  return LowerWindowsDIVLibCall(Op, DAG, Signed, DBZCHK);
+}
+
+void ARMTargetLowering::ExpandDIV_Windows(
+    SDValue Op, SelectionDAG &DAG, bool Signed,
+    SmallVectorImpl<SDValue> &Results) const {
+  const auto &DL = DAG.getDataLayout();
+  const auto &TLI = DAG.getTargetLoweringInfo();
+
+  EVT VT = Op.getValueType();
+  assert(VT == MVT::i64 && "unexpected type for custom lowering DIV");
+  SDLoc dl(Op);
+
+  SDValue Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32, Op.getOperand(1),
+                           DAG.getConstant(0, dl, MVT::i32));
+  SDValue Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32, Op.getOperand(1),
+                           DAG.getConstant(1, dl, MVT::i32));
+  SDValue Or = DAG.getNode(ISD::OR, dl, MVT::i32, Lo, Hi);
+
+  SDValue DBZCHK =
+      DAG.getNode(ARMISD::WIN__DBZCHK, dl, MVT::Other, DAG.getEntryNode(), Or);
+
+  SDValue Result = LowerWindowsDIVLibCall(Op, DAG, Signed, DBZCHK);
+
+  SDValue Lower = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Result);
+  SDValue Upper = DAG.getNode(ISD::SRL, dl, MVT::i64, Result,
+                              DAG.getConstant(32, dl, TLI.getPointerTy(DL)));
+  Upper = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Upper);
+
+  Results.push_back(Lower);
+  Results.push_back(Upper);
+}
+
 static SDValue LowerAtomicLoadStore(SDValue Op, SelectionDAG &DAG) {
   // Monotonic load/store is legal for all targets
   if (cast<AtomicSDNode>(Op)->getOrdering() <= Monotonic)
@@ -6736,8 +6819,14 @@ SDValue ARMTargetLowering::LowerOperatio
   case ISD::CONCAT_VECTORS: return LowerCONCAT_VECTORS(Op, DAG);
   case ISD::FLT_ROUNDS_:   return LowerFLT_ROUNDS_(Op, DAG);
   case ISD::MUL:           return LowerMUL(Op, DAG);
-  case ISD::SDIV:          return LowerSDIV(Op, DAG);
-  case ISD::UDIV:          return LowerUDIV(Op, DAG);
+  case ISD::SDIV:
+    if (Subtarget->isTargetWindows())
+      return LowerDIV_Windows(Op, DAG, /* Signed */ true);
+    return LowerSDIV(Op, DAG);
+  case ISD::UDIV:
+    if (Subtarget->isTargetWindows())
+      return LowerDIV_Windows(Op, DAG, /* Signed */ false);
+    return LowerUDIV(Op, DAG);
   case ISD::ADDC:
   case ISD::ADDE:
   case ISD::SUBC:
@@ -6758,13 +6847,14 @@ SDValue ARMTargetLowering::LowerOperatio
     llvm_unreachable("Don't know how to custom lower this!");
   case ISD::FP_ROUND: return LowerFP_ROUND(Op, DAG);
   case ISD::FP_EXTEND: return LowerFP_EXTEND(Op, DAG);
+  case ARMISD::WIN__DBZCHK: return SDValue();
   }
 }
 
 /// ReplaceNodeResults - Replace the results of node with an illegal result
 /// type with new values built out of custom code.
 void ARMTargetLowering::ReplaceNodeResults(SDNode *N,
-                                           SmallVectorImpl<SDValue>&Results,
+                                           SmallVectorImpl<SDValue> &Results,
                                            SelectionDAG &DAG) const {
   SDValue Res;
   switch (N->getOpcode()) {
@@ -6787,6 +6877,11 @@ void ARMTargetLowering::ReplaceNodeResul
   case ISD::READCYCLECOUNTER:
     ReplaceREADCYCLECOUNTER(N, Results, DAG, Subtarget);
     return;
+  case ISD::UDIV:
+  case ISD::SDIV:
+    assert(Subtarget->isTargetWindows() && "can only expand DIV on Windows");
+    return ExpandDIV_Windows(SDValue(N, 0), DAG, N->getOpcode() == ISD::SDIV,
+                             Results);
   }
   if (Res.getNode())
     Results.push_back(Res);
@@ -7711,6 +7806,32 @@ ARMTargetLowering::EmitLowered__chkstk(M
 }
 
 MachineBasicBlock *
+ARMTargetLowering::EmitLowered__dbzchk(MachineInstr *MI,
+                                       MachineBasicBlock *MBB) const {
+  DebugLoc DL = MI->getDebugLoc();
+  MachineFunction *MF = MBB->getParent();
+  const TargetInstrInfo *TII = Subtarget->getInstrInfo();
+
+  MachineBasicBlock *ContBB = MF->CreateMachineBasicBlock();
+  MF->push_back(ContBB);
+  ContBB->splice(ContBB->begin(), MBB,
+                 std::next(MachineBasicBlock::iterator(MI)), MBB->end());
+  MBB->addSuccessor(ContBB);
+
+  MachineBasicBlock *TrapBB = MF->CreateMachineBasicBlock();
+  MF->push_back(TrapBB);
+  BuildMI(TrapBB, DL, TII->get(ARM::t2UDF)).addImm(249);
+  MBB->addSuccessor(TrapBB);
+
+  BuildMI(*MBB, MI, DL, TII->get(ARM::tCBZ))
+      .addReg(MI->getOperand(0).getReg())
+      .addMBB(TrapBB);
+
+  MI->eraseFromParent();
+  return ContBB;
+}
+
+MachineBasicBlock *
 ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
                                                MachineBasicBlock *BB) const {
   const TargetInstrInfo *TII = Subtarget->getInstrInfo();
@@ -7964,6 +8085,8 @@ ARMTargetLowering::EmitInstrWithCustomIn
     return EmitStructByval(MI, BB);
   case ARM::WIN__CHKSTK:
     return EmitLowered__chkstk(MI, BB);
+  case ARM::WIN__DBZCHK:
+    return EmitLowered__dbzchk(MI, BB);
   }
 }
 

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.h?rev=248561&r1=248560&r2=248561&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.h Fri Sep 25 00:15:46 2015
@@ -92,6 +92,7 @@ namespace llvm {
       PRELOAD,      // Preload
 
       WIN__CHKSTK,  // Windows' __chkstk call to do stack probing.
+      WIN__DBZCHK,  // Windows' divide by zero check
 
       VCEQ,         // Vector compare equal.
       VCEQZ,        // Vector compare equal to zero.
@@ -525,6 +526,11 @@ namespace llvm {
                               const ARMSubtarget *ST) const;
     SDValue LowerFSINCOS(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerDivRem(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerDIV_Windows(SDValue Op, SelectionDAG &DAG, bool Signed) const;
+    void ExpandDIV_Windows(SDValue Op, SelectionDAG &DAG, bool Signed,
+                           SmallVectorImpl<SDValue> &Results) const;
+    SDValue LowerWindowsDIVLibCall(SDValue Op, SelectionDAG &DAG, bool Signed,
+                                   SDValue &Chain) const;
     SDValue LowerREM(SDNode *N, SelectionDAG &DAG) const;
     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFP_ROUND(SDValue Op, SelectionDAG &DAG) const;
@@ -635,6 +641,8 @@ namespace llvm {
 
     MachineBasicBlock *EmitLowered__chkstk(MachineInstr *MI,
                                            MachineBasicBlock *MBB) const;
+    MachineBasicBlock *EmitLowered__dbzchk(MachineInstr *MI,
+                                           MachineBasicBlock *MBB) const;
   };
 
   enum NEONModImmType {

Modified: llvm/trunk/lib/Target/ARM/ARMInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMInstrInfo.td?rev=248561&r1=248560&r2=248561&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMInstrInfo.td (original)
+++ llvm/trunk/lib/Target/ARM/ARMInstrInfo.td Fri Sep 25 00:15:46 2015
@@ -71,6 +71,8 @@ def SDT_ARMTCRET : SDTypeProfile<0, 1, [
 def SDT_ARMBFI : SDTypeProfile<1, 3, [SDTCisVT<0, i32>, SDTCisVT<1, i32>,
                                       SDTCisVT<2, i32>, SDTCisVT<3, i32>]>;
 
+def SDT_WIN__DBZCHK : SDTypeProfile<0, 1, [SDTCisVT<0, i32>]>;
+
 def SDTBinaryArithWithFlags : SDTypeProfile<2, 2,
                                             [SDTCisSameAs<0, 2>,
                                              SDTCisSameAs<0, 3>,
@@ -5239,6 +5241,12 @@ def win__chkstk : SDNode<"ARMISD::WIN__C
 let usesCustomInserter = 1, Uses = [R4], Defs = [R4, SP] in
   def WIN__CHKSTK : PseudoInst<(outs), (ins), NoItinerary, [(win__chkstk)]>;
 
+def win__dbzchk : SDNode<"ARMISD::WIN__DBZCHK", SDT_WIN__DBZCHK,
+                         [SDNPHasChain, SDNPSideEffect, SDNPOutGlue]>;
+let usesCustomInserter = 1, Defs = [CPSR] in
+  def WIN__DBZCHK : PseudoInst<(outs), (ins GPR:$divisor), NoItinerary,
+                               [(win__dbzchk GPR:$divisor)]>;
+
 //===----------------------------------------------------------------------===//
 // TLS Instructions
 //

Added: llvm/trunk/test/CodeGen/ARM/Windows/division.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/Windows/division.ll?rev=248561&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/Windows/division.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/Windows/division.ll Fri Sep 25 00:15:46 2015
@@ -0,0 +1,49 @@
+; RUN: llc -mtriple thumbv7-windows-itanium -filetype asm -o - %s | FileCheck %s
+; RUN: llc -mtriple thumbv7-windows-msvc -filetype asm -o - %s | FileCheck %s
+
+define arm_aapcs_vfpcc i32 @sdiv32(i32 %divisor, i32 %divident) {
+entry:
+  %div = sdiv i32 %divident, %divisor
+  ret i32 %div
+}
+
+; CHECK-LABEL: sdiv32:
+; CHECK: cbz r0
+; CHECK: bl __rt_sdiv
+; CHECK: udf.w #249
+
+define arm_aapcs_vfpcc i32 @udiv32(i32 %divisor, i32 %divident) {
+entry:
+  %div = udiv i32 %divident, %divisor
+  ret i32 %div
+}
+
+; CHECK-LABEL: udiv32:
+; CHECK: cbz r0
+; CHECK: bl __rt_udiv
+; CHECK: udf.w #249
+
+define arm_aapcs_vfpcc i64 @sdiv64(i64 %divisor, i64 %divident) {
+entry:
+  %div = sdiv i64 %divident, %divisor
+  ret i64 %div
+}
+
+; CHECK-LABEL: sdiv64:
+; CHECK: orr.w r12, r0, r1
+; CHECK-NEXT: cbz r12
+; CHECK: bl __rt_sdiv64
+; CHECK: udf.w #249
+
+define arm_aapcs_vfpcc i64 @udiv64(i64 %divisor, i64 %divident) {
+entry:
+  %div = udiv i64 %divident, %divisor
+  ret i64 %div
+}
+
+; CHECK-LABEL: udiv64:
+; CHECK: orr.w r12, r0, r1
+; CHECK-NEXT: cbz r12
+; CHECK: bl __rt_udiv64
+; CHECK: udf.w #249
+

Modified: llvm/trunk/test/CodeGen/ARM/Windows/libcalls.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/Windows/libcalls.ll?rev=248561&r1=248560&r2=248561&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/Windows/libcalls.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/Windows/libcalls.ll Fri Sep 25 00:15:46 2015
@@ -1,42 +1,6 @@
 ; RUN: llc -mtriple thumbv7-windows-itanium -filetype asm -o - %s | FileCheck %s
 ; RUN: llc -mtriple thumbv7-windows-msvc -filetype asm -o - %s | FileCheck %s
 
-define arm_aapcs_vfpcc i32 @sdiv32(i32 %divisor, i32 %divident) {
-entry:
-  %div = sdiv i32 %divident, %divisor
-  ret i32 %div
-}
-
-; CHECK-LABEL: sdiv32
-; CHECK: b __rt_sdiv
-
-define arm_aapcs_vfpcc i64 @sdiv64(i64 %divisor, i64 %divident) {
-entry:
-  %div = sdiv i64 %divident, %divisor
-  ret i64 %div
-}
-
-; CHECK-LABEL: sdiv64
-; CHECK: bl __rt_sdiv64
-
-define arm_aapcs_vfpcc i32 @udiv32(i32 %divisor, i32 %divident) {
-entry:
-  %div = udiv i32 %divident, %divisor
-  ret i32 %div
-}
-
-; CHECK-LABEL: udiv32
-; CHECK: b __rt_udiv
-
-define arm_aapcs_vfpcc i64 @udiv64(i64 %divisor, i64 %divident) {
-entry:
-  %div = udiv i64 %divident, %divisor
-  ret i64 %div
-}
-
-; CHECK-LABEL: udiv64
-; CHECK: bl __rt_udiv64
-
 define arm_aapcs_vfpcc i64 @stoi64(float %f) {
 entry:
   %conv = fptosi float %f to i64




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