Reapply r298417 "[ARM] Recommit the glueless lowering of addc/adde in Thumb1"

The UB in t2_so_imm_neg conversion has been addressed under D31242 / r298512

This reverts commit r298482.

llvm-svn: 298562

3 files changed, 167 insertions, 31 deletions

diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 72868828596..4f5711ca9a7 100644
--- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -2028,6 +2028,16 @@ static const AddSubFlagsOpcodePair AddSubFlagsOpcodeMap[] = {
   {ARM::RSBSrsi, ARM::RSBrsi},
   {ARM::RSBSrsr, ARM::RSBrsr},
 
+  {ARM::tADDSi3, ARM::tADDi3},
+  {ARM::tADDSi8, ARM::tADDi8},
+  {ARM::tADDSrr, ARM::tADDrr},
+  {ARM::tADCS, ARM::tADC},
+
+  {ARM::tSUBSi3, ARM::tSUBi3},
+  {ARM::tSUBSi8, ARM::tSUBi8},
+  {ARM::tSUBSrr, ARM::tSUBrr},
+  {ARM::tSBCS, ARM::tSBC},
+
   {ARM::t2ADDSri, ARM::t2ADDri},
   {ARM::t2ADDSrr, ARM::t2ADDrr},
   {ARM::t2ADDSrs, ARM::t2ADDrs},
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index e3723788223..0c17211cce3 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -822,13 +822,10 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
   setOperationAction(ISD::SRL,       MVT::i64, Custom);
   setOperationAction(ISD::SRA,       MVT::i64, Custom);
 
-  if (!Subtarget->isThumb1Only()) {
-    // FIXME: We should do this for Thumb1 as well.
-    setOperationAction(ISD::ADDC,    MVT::i32, Custom);
-    setOperationAction(ISD::ADDE,    MVT::i32, Custom);
-    setOperationAction(ISD::SUBC,    MVT::i32, Custom);
-    setOperationAction(ISD::SUBE,    MVT::i32, Custom);
-  }
+  setOperationAction(ISD::ADDC,      MVT::i32, Custom);
+  setOperationAction(ISD::ADDE,      MVT::i32, Custom);
+  setOperationAction(ISD::SUBC,      MVT::i32, Custom);
+  setOperationAction(ISD::SUBE,      MVT::i32, Custom);
 
   if (!Subtarget->isThumb1Only() && Subtarget->hasV6T2Ops())
     setOperationAction(ISD::BITREVERSE, MVT::i32, Legal);
@@ -9096,19 +9093,45 @@ void ARMTargetLowering::AdjustInstrPostInstrSelection(MachineInstr &MI,
 
   // Rename pseudo opcodes.
   unsigned NewOpc = convertAddSubFlagsOpcode(MI.getOpcode());
+  unsigned ccOutIdx;
   if (NewOpc) {
     const ARMBaseInstrInfo *TII = Subtarget->getInstrInfo();
     MCID = &TII->get(NewOpc);
 
-    assert(MCID->getNumOperands() == MI.getDesc().getNumOperands() + 1 &&
-           "converted opcode should be the same except for cc_out");
+    assert(MCID->getNumOperands() ==
+           MI.getDesc().getNumOperands() + 5 - MI.getDesc().getSize()
+        && "converted opcode should be the same except for cc_out"
+           " (and, on Thumb1, pred)");
 
     MI.setDesc(*MCID);
 
     // Add the optional cc_out operand
     MI.addOperand(MachineOperand::CreateReg(0, /*isDef=*/true));
-  }
-  unsigned ccOutIdx = MCID->getNumOperands() - 1;
+
+    // On Thumb1, move all input operands to the end, then add the predicate
+    if (Subtarget->isThumb1Only()) {
+      for (unsigned c = MCID->getNumOperands() - 4; c--;) {
+        MI.addOperand(MI.getOperand(1));
+        MI.RemoveOperand(1);
+      }
+
+      // Restore the ties
+      for (unsigned i = MI.getNumOperands(); i--;) {
+        const MachineOperand& op = MI.getOperand(i);
+        if (op.isReg() && op.isUse()) {
+          int DefIdx = MCID->getOperandConstraint(i, MCOI::TIED_TO);
+          if (DefIdx != -1)
+            MI.tieOperands(DefIdx, i);
+        }
+      }
+
+      MI.addOperand(MachineOperand::CreateImm(ARMCC::AL));
+      MI.addOperand(MachineOperand::CreateReg(0, /*isDef=*/false));
+      ccOutIdx = 1;
+    } else
+      ccOutIdx = MCID->getNumOperands() - 1;
+  } else
+    ccOutIdx = MCID->getNumOperands() - 1;
 
   // Any ARM instruction that sets the 's' bit should specify an optional
   // "cc_out" operand in the last operand position.
@@ -9139,7 +9162,9 @@ void ARMTargetLowering::AdjustInstrPostInstrSelection(MachineInstr &MI,
   if (deadCPSR) {
     assert(!MI.getOperand(ccOutIdx).getReg() &&
            "expect uninitialized optional cc_out operand");
-    return;
+    // Thumb1 instructions must have the S bit even if the CPSR is dead.
+    if (!Subtarget->isThumb1Only())
+      return;
   }
 
   // If this instruction was defined with an optional CPSR def and its dag node
@@ -9759,6 +9784,48 @@ static SDValue PerformUMLALCombine(SDNode *N, SelectionDAG &DAG,
     return SDValue();
 }
 
+static SDValue PerformAddcSubcCombine(SDNode *N, SelectionDAG &DAG,
+                                      const ARMSubtarget *Subtarget) {
+  if (Subtarget->isThumb1Only()) {
+    SDValue RHS = N->getOperand(1);
+    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS)) {
+      int32_t imm = C->getSExtValue();
+      if (imm < 0 && imm > INT_MIN) {
+        SDLoc DL(N);
+        RHS = DAG.getConstant(-imm, DL, MVT::i32);
+        unsigned Opcode = (N->getOpcode() == ARMISD::ADDC) ? ARMISD::SUBC
+                                                           : ARMISD::ADDC;
+        return DAG.getNode(Opcode, DL, N->getVTList(), N->getOperand(0), RHS);
+      }
+    }
+  }
+  return SDValue();
+}
+
+static SDValue PerformAddeSubeCombine(SDNode *N, SelectionDAG &DAG,
+                                      const ARMSubtarget *Subtarget) {
+  if (Subtarget->isThumb1Only()) {
+    SDValue RHS = N->getOperand(1);
+    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS)) {
+      int64_t imm = C->getSExtValue();
+      if (imm < 0) {
+        SDLoc DL(N);
+
+        // The with-carry-in form matches bitwise not instead of the negation.
+        // Effectively, the inverse interpretation of the carry flag already
+        // accounts for part of the negation.
+        RHS = DAG.getConstant(~imm, DL, MVT::i32);
+
+        unsigned Opcode = (N->getOpcode() == ARMISD::ADDE) ? ARMISD::SUBE
+                                                           : ARMISD::ADDE;
+        return DAG.getNode(Opcode, DL, N->getVTList(),
+                           N->getOperand(0), RHS, N->getOperand(2));
+      }
+    }
+  }
+  return SDValue();
+}
+
 /// PerformADDECombine - Target-specific dag combine transform from
 /// ARMISD::ADDC, ARMISD::ADDE, and ISD::MUL_LOHI to MLAL or
 /// ARMISD::ADDC, ARMISD::ADDE and ARMISD::UMLAL to ARMISD::UMAAL
@@ -9767,7 +9834,7 @@ static SDValue PerformADDECombine(SDNode *N,
                                   const ARMSubtarget *Subtarget) {
   // Only ARM and Thumb2 support UMLAL/SMLAL.
   if (Subtarget->isThumb1Only())
-    return SDValue();
+    return PerformAddeSubeCombine(N, DCI.DAG, Subtarget);
 
   // Only perform the checks after legalize when the pattern is available.
   if (DCI.isBeforeLegalize()) return SDValue();
@@ -11867,6 +11934,9 @@ SDValue ARMTargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::OR:         return PerformORCombine(N, DCI, Subtarget);
   case ISD::XOR:        return PerformXORCombine(N, DCI, Subtarget);
   case ISD::AND:        return PerformANDCombine(N, DCI, Subtarget);
+  case ARMISD::ADDC:
+  case ARMISD::SUBC:    return PerformAddcSubcCombine(N, DCI.DAG, Subtarget);
+  case ARMISD::SUBE:    return PerformAddeSubeCombine(N, DCI.DAG, Subtarget);
   case ARMISD::BFI:     return PerformBFICombine(N, DCI);
   case ARMISD::VMOVRRD: return PerformVMOVRRDCombine(N, DCI, Subtarget);
   case ARMISD::VMOVDRR: return PerformVMOVDRRCombine(N, DCI.DAG);
diff --git a/llvm/lib/Target/ARM/ARMInstrThumb.td b/llvm/lib/Target/ARM/ARMInstrThumb.td
index e6934cb04ef..c372bcdc262 100644
--- a/llvm/lib/Target/ARM/ARMInstrThumb.td
+++ b/llvm/lib/Target/ARM/ARMInstrThumb.td
@@ -922,7 +922,7 @@ let isAdd = 1 in {
   def tADC :                      // A8.6.2
     T1sItDPEncode<0b0101, (outs tGPR:$Rdn), (ins tGPR:$Rn, tGPR:$Rm), IIC_iALUr,
                   "adc", "\t$Rdn, $Rm",
-                  [(set tGPR:$Rdn, (adde tGPR:$Rn, tGPR:$Rm))]>, Sched<[WriteALU]>;
+                  []>, Sched<[WriteALU]>;
 
   // Add immediate
   def tADDi3 :                    // A8.6.4 T1
@@ -950,6 +950,43 @@ let isAdd = 1 in {
                   "add", "\t$Rd, $Rn, $Rm",
                   [(set tGPR:$Rd, (add tGPR:$Rn, tGPR:$Rm))]>, Sched<[WriteALU]>;
 
+  /// Similar to the above except these set the 's' bit so the
+  /// instruction modifies the CPSR register.
+  ///
+  /// These opcodes will be converted to the real non-S opcodes by
+  /// AdjustInstrPostInstrSelection after giving then an optional CPSR operand.
+  let hasPostISelHook = 1, Defs = [CPSR] in {
+    let isCommutable = 1 in
+    def tADCS : tPseudoInst<(outs tGPR:$Rdn), (ins tGPR:$Rn, tGPR:$Rm),
+                            2, IIC_iALUr,
+                            [(set tGPR:$Rdn, CPSR, (ARMadde tGPR:$Rn, tGPR:$Rm,
+                                                            CPSR))]>,
+                Requires<[IsThumb1Only]>,
+                Sched<[WriteALU]>;
+
+    def tADDSi3 : tPseudoInst<(outs tGPR:$Rd), (ins tGPR:$Rm, imm0_7:$imm3),
+                              2, IIC_iALUi,
+                              [(set tGPR:$Rd, CPSR, (ARMaddc tGPR:$Rm,
+                                                             imm0_7:$imm3))]>,
+                  Requires<[IsThumb1Only]>,
+                  Sched<[WriteALU]>;
+
+    def tADDSi8 : tPseudoInst<(outs tGPR:$Rdn), (ins tGPR:$Rn, imm0_255:$imm8),
+                              2, IIC_iALUi,
+                              [(set tGPR:$Rdn, CPSR, (ARMaddc tGPR:$Rn,
+                                                      imm8_255:$imm8))]>,
+                  Requires<[IsThumb1Only]>,
+                  Sched<[WriteALU]>;
+
+    let isCommutable = 1 in
+    def tADDSrr : tPseudoInst<(outs tGPR:$Rd), (ins tGPR:$Rn, tGPR:$Rm),
+                              2, IIC_iALUr,
+                              [(set tGPR:$Rd, CPSR, (ARMaddc tGPR:$Rn,
+                                                             tGPR:$Rm))]>,
+                  Requires<[IsThumb1Only]>,
+                  Sched<[WriteALU]>;
+  }
+
   let hasSideEffects = 0 in
   def tADDhirr : T1pIt<(outs GPR:$Rdn), (ins GPR:$Rn, GPR:$Rm), IIC_iALUr,
                        "add", "\t$Rdn, $Rm", []>,
@@ -1215,7 +1252,7 @@ def tSBC :                      // A8.6.151
   T1sItDPEncode<0b0110, (outs tGPR:$Rdn), (ins tGPR:$Rn, tGPR:$Rm),
                 IIC_iALUr,
                 "sbc", "\t$Rdn, $Rm",
-                [(set tGPR:$Rdn, (sube tGPR:$Rn, tGPR:$Rm))]>,
+                []>,
                 Sched<[WriteALU]>;
 
 // Subtract immediate
@@ -1252,6 +1289,41 @@ def tSUBrr :                    // A8.6.212
                 [(set tGPR:$Rd, (sub tGPR:$Rn, tGPR:$Rm))]>,
                 Sched<[WriteALU]>;
 
+/// Similar to the above except these set the 's' bit so the
+/// instruction modifies the CPSR register.
+///
+/// These opcodes will be converted to the real non-S opcodes by
+/// AdjustInstrPostInstrSelection after giving then an optional CPSR operand.
+let hasPostISelHook = 1, Defs = [CPSR] in {
+  def tSBCS : tPseudoInst<(outs tGPR:$Rdn), (ins tGPR:$Rn, tGPR:$Rm),
+                          2, IIC_iALUr,
+                          [(set tGPR:$Rdn, CPSR, (ARMsube tGPR:$Rn, tGPR:$Rm,
+                                                          CPSR))]>,
+              Requires<[IsThumb1Only]>,
+              Sched<[WriteALU]>;
+
+  def tSUBSi3 : tPseudoInst<(outs tGPR:$Rd), (ins tGPR:$Rm, imm0_7:$imm3),
+                            2, IIC_iALUi,
+                            [(set tGPR:$Rd, CPSR, (ARMsubc tGPR:$Rm,
+                                                           imm0_7:$imm3))]>,
+                Requires<[IsThumb1Only]>,
+                Sched<[WriteALU]>;
+
+  def tSUBSi8 : tPseudoInst<(outs tGPR:$Rdn), (ins tGPR:$Rn, imm0_255:$imm8),
+                            2, IIC_iALUi,
+                            [(set tGPR:$Rdn, CPSR, (ARMsubc tGPR:$Rn,
+                                                            imm8_255:$imm8))]>,
+                Requires<[IsThumb1Only]>,
+                Sched<[WriteALU]>;
+
+  def tSUBSrr : tPseudoInst<(outs tGPR:$Rd), (ins tGPR:$Rn, tGPR:$Rm),
+                            2, IIC_iALUr,
+                            [(set tGPR:$Rd, CPSR, (ARMsubc tGPR:$Rn,
+                                                           tGPR:$Rm))]>,
+                Requires<[IsThumb1Only]>,
+                Sched<[WriteALU]>;
+}
+
 // Sign-extend byte
 def tSXTB :                     // A8.6.222
   T1pIMiscEncode<{0,0,1,0,0,1,?}, (outs tGPR:$Rd), (ins tGPR:$Rm),
@@ -1412,22 +1484,6 @@ def : T1Pat<(ARMcmpZ tGPR:$Rn, imm0_255:$imm8),
 def : T1Pat<(ARMcmpZ tGPR:$Rn, tGPR:$Rm),
             (tCMPr   tGPR:$Rn, tGPR:$Rm)>;
 
-// Add with carry
-def : T1Pat<(addc   tGPR:$lhs, imm0_7:$rhs),
-            (tADDi3 tGPR:$lhs, imm0_7:$rhs)>;
-def : T1Pat<(addc   tGPR:$lhs, imm8_255:$rhs),
-            (tADDi8 tGPR:$lhs, imm8_255:$rhs)>;
-def : T1Pat<(addc   tGPR:$lhs, tGPR:$rhs),
-            (tADDrr tGPR:$lhs, tGPR:$rhs)>;
-
-// Subtract with carry
-def : T1Pat<(addc   tGPR:$lhs, imm0_7_neg:$rhs),
-            (tSUBi3 tGPR:$lhs, imm0_7_neg:$rhs)>;
-def : T1Pat<(addc   tGPR:$lhs, imm8_255_neg:$rhs),
-            (tSUBi8 tGPR:$lhs, imm8_255_neg:$rhs)>;
-def : T1Pat<(subc   tGPR:$lhs, tGPR:$rhs),
-            (tSUBrr tGPR:$lhs, tGPR:$rhs)>;
-
 // Bswap 16 with load/store
 def : T1Pat<(srl (bswap (extloadi16 t_addrmode_is2:$addr)), (i32 16)),
             (tREV16 (tLDRHi t_addrmode_is2:$addr))>;