Follow up to r138791.

Add a instruction flag: hasPostISelHook which tells the pre-RA scheduler to
call a target hook to adjust the instruction. For ARM, this is used to
adjust instructions which may be setting the 's' flag. ADC, SBC, RSB, and RSC
instructions have implicit def of CPSR (required since it now uses CPSR physical
register dependency rather than "glue"). If the carry flag is used, then the
target hook will *fill in* the optional operand with CPSR. Otherwise, the hook
will remove the CPSR implicit def from the MachineInstr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138810 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 44 insertions, 2 deletions

diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 568f66c039..1e45ec6d11 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -761,6 +761,10 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
            i != e; ++i)
         MI->addRegisterDead(IDList[i-II.getNumDefs()], TRI);
     }
+
+  // Run post-isel target hook to adjust this instruction if needed.
+  if (II.hasPostISelHook())
+    TLI->AdjustInstrPostInstrSelection(MI, Node);
 }
 
 /// EmitSpecialNode - Generate machine code for a target-independent node and
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index dda018b939..7a3ea86e8c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -177,6 +177,16 @@ TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
   return 0;
 }
 
+void TargetLowering::AdjustInstrPostInstrSelection(MachineInstr *MI,
+                                                   SDNode *Node) const {
+#ifndef NDEBUG
+  dbgs() << "If a target marks an instruction with "
+          "'hasPostISelHook', it must implement "
+          "TargetLowering::AdjustInstrPostInstrSelection!";
+#endif
+  llvm_unreachable(0);
+}
+
 //===----------------------------------------------------------------------===//
 // SelectionDAGISel code
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 29fb268ef4..52684663af 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -5474,6 +5474,29 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
   }
 }
 
+void ARMTargetLowering::AdjustInstrPostInstrSelection(MachineInstr *MI,
+                                                      SDNode *Node) const {
+  // Adjust potentially 's' setting instructions after isel, i.e. ADC, SBC,
+  // RSB, RSC. Coming out of isel, they have an implicit CPSR def, but the
+  // optional operand is not filled in. If the carry bit is used, then change
+  // the optional operand to CPSR. Otherwise, remove the CPSR implicit def.
+  const MCInstrDesc &MCID = MI->getDesc();
+  if (Node->hasAnyUseOfValue(1)) {
+    MachineOperand &MO = MI->getOperand(MCID.getNumOperands() - 2);
+    MO.setReg(ARM::CPSR);
+    MO.setIsDef(true);
+  } else {
+    for (unsigned i = MCID.getNumOperands(), e = MI->getNumOperands();
+         i != e; ++i) {
+      const MachineOperand &MO = MI->getOperand(i);
+      if (MO.isReg() && MO.isDef() && MO.getReg() == ARM::CPSR) {
+        MI->RemoveOperand(i);
+        break;
+      }
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //                           ARM Optimization Hooks
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 4a07ebf97b..92164aef00 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -249,6 +249,9 @@ namespace llvm {
       EmitInstrWithCustomInserter(MachineInstr *MI,
                                   MachineBasicBlock *MBB) const;
 
+    virtual void
+    AdjustInstrPostInstrSelection(MachineInstr *MI, SDNode *Node) const;
+
     SDValue PerformCMOVCombine(SDNode *N, SelectionDAG &DAG) const;
     virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
 
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index f4d13577de..08b0954efa 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -1290,7 +1290,7 @@ class AI_exta_rrot_np<bits<8> opcod, string opc>
 /// AI1_adde_sube_irs - Define instructions and patterns for adde and sube.
 multiclass AI1_adde_sube_irs<bits<4> opcod, string opc, PatFrag opnode,
                              string baseOpc, bit Commutable = 0> {
-  let Defs = [CPSR], Uses = [CPSR] in {
+  let hasPostISelHook = 1, Defs = [CPSR], Uses = [CPSR] in {
   def ri : AsI1<opcod, (outs GPR:$Rd), (ins GPR:$Rn, so_imm:$imm),
                 DPFrm, IIC_iALUi, opc, "\t$Rd, $Rn, $imm",
                [(set GPR:$Rd, CPSR, (opnode GPR:$Rn, so_imm:$imm, CPSR))]>,
@@ -1378,7 +1378,7 @@ multiclass AI1_adde_sube_irs<bits<4> opcod, string opc, PatFrag opnode,
 /// AI1_rsc_irs - Define instructions and patterns for rsc
 multiclass AI1_rsc_irs<bits<4> opcod, string opc, PatFrag opnode,
                        string baseOpc> {
-  let Defs = [CPSR], Uses = [CPSR] in {
+  let hasPostISelHook = 1, Defs = [CPSR], Uses = [CPSR] in {
   def ri : AsI1<opcod, (outs GPR:$Rd), (ins GPR:$Rn, so_imm:$imm),
                 DPFrm, IIC_iALUi, opc, "\t$Rd, $Rn, $imm",
                [(set GPR:$Rd, CPSR, (opnode so_imm:$imm, GPR:$Rn, CPSR))]>,
diff --git a/lib/Target/ARM/ARMInstrThumb2.td b/lib/Target/ARM/ARMInstrThumb2.td
index 34a9147233..a7652f670a 100644
--- a/lib/Target/ARM/ARMInstrThumb2.td
+++ b/lib/Target/ARM/ARMInstrThumb2.td
@@ -1661,10 +1661,12 @@ defm t2SUBS : T2I_bin_s_irs <0b1101, "sub",
                              IIC_iALUi, IIC_iALUr, IIC_iALUsi,
                              BinOpFrag<(ARMsubc node:$LHS, node:$RHS)>>;
 
+let hasPostISelHook = 1 in {
 defm t2ADC  : T2I_adde_sube_irs<0b1010, "adc",
               BinOpWithFlagFrag<(ARMadde node:$LHS, node:$RHS, node:$FLAG)>, 1>;
 defm t2SBC  : T2I_adde_sube_irs<0b1011, "sbc",
               BinOpWithFlagFrag<(ARMsube node:$LHS, node:$RHS, node:$FLAG)>>;
+}
 
 // RSB
 defm t2RSB  : T2I_rbin_irs  <0b1110, "rsb",