[RISCV] Software-guard direct calls in large code model

Author: jaidTw

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -19696,11 +19696,14 @@ SDValue RISCVTargetLowering::LowerCall(CallLoweringInfo &CLI,
   // If the callee is a GlobalAddress/ExternalSymbol node, turn it into a
   // TargetGlobalAddress/TargetExternalSymbol node so that legalize won't
   // split it and then direct call can be matched by PseudoCALL.
+  bool CalleeIsLargeExternalSymbol = false;
   if (getTargetMachine().getCodeModel() == CodeModel::Large) {
     if (auto *S = dyn_cast<GlobalAddressSDNode>(Callee))
       Callee = getLargeGlobalAddress(S, DL, PtrVT, DAG);
-    else if (auto *S = dyn_cast<ExternalSymbolSDNode>(Callee))
+    else if (auto *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
       Callee = getLargeExternalSymbol(S, DL, PtrVT, DAG);
+      CalleeIsLargeExternalSymbol = true;
+    }
   } else if (GlobalAddressSDNode *S = dyn_cast<GlobalAddressSDNode>(Callee)) {
     const GlobalValue *GV = S->getGlobal();
     Callee = DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0, RISCVII::MO_CALL);
@@ -19736,16 +19739,32 @@ SDValue RISCVTargetLowering::LowerCall(CallLoweringInfo &CLI,
   // Emit the call.
   SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
 
+  // Use software guarded branch for large code model non-indirect calls
+  // Tail call to external symbol will have a null CLI.CB and we need another
+  // way to determine the callsite type
+  bool NeedSWGuarded = false;
+  if (getTargetMachine().getCodeModel() == CodeModel::Large &&
+      Subtarget.hasStdExtZicfilp() &&
+      ((CLI.CB && !CLI.CB->isIndirectCall()) || CalleeIsLargeExternalSymbol))
+    NeedSWGuarded = true;
+
   if (IsTailCall) {
     MF.getFrameInfo().setHasTailCall();
-    SDValue Ret = DAG.getNode(RISCVISD::TAIL, DL, NodeTys, Ops);
+    SDValue Ret;
+    if (NeedSWGuarded)
+      Ret = DAG.getNode(RISCVISD::SW_GUARDED_TAIL, DL, NodeTys, Ops);
+    else
+      Ret = DAG.getNode(RISCVISD::TAIL, DL, NodeTys, Ops);
     if (CLI.CFIType)
       Ret.getNode()->setCFIType(CLI.CFIType->getZExtValue());
     DAG.addNoMergeSiteInfo(Ret.getNode(), CLI.NoMerge);
     return Ret;
   }
 
-  Chain = DAG.getNode(RISCVISD::CALL, DL, NodeTys, Ops);
+  if (NeedSWGuarded)
+    Chain = DAG.getNode(RISCVISD::SW_GUARDED_CALL, DL, NodeTys, Ops);
+  else
+    Chain = DAG.getNode(RISCVISD::CALL, DL, NodeTys, Ops);
   if (CLI.CFIType)
     Chain.getNode()->setCFIType(CLI.CFIType->getZExtValue());
   DAG.addNoMergeSiteInfo(Chain.getNode(), CLI.NoMerge);
@@ -20193,6 +20212,8 @@ const char *RISCVTargetLowering::getTargetNodeName(unsigned Opcode) const {
   NODE_NAME_CASE(CZERO_EQZ)
   NODE_NAME_CASE(CZERO_NEZ)
   NODE_NAME_CASE(SW_GUARDED_BRIND)
+  NODE_NAME_CASE(SW_GUARDED_CALL)
+  NODE_NAME_CASE(SW_GUARDED_TAIL)
   NODE_NAME_CASE(TUPLE_INSERT)
   NODE_NAME_CASE(TUPLE_EXTRACT)
   NODE_NAME_CASE(SF_VC_XV_SE)

llvm/lib/Target/RISCV/RISCVISelLowering.h

@@ -411,9 +411,12 @@ enum NodeType : unsigned {
   CZERO_EQZ, // vt.maskc for XVentanaCondOps.
   CZERO_NEZ, // vt.maskcn for XVentanaCondOps.
 
-  /// Software guarded BRIND node. Operand 0 is the chain operand and
-  /// operand 1 is the target address.
+  // Software guarded BRIND node. Operand 0 is the chain operand and
+  // operand 1 is the target address.
   SW_GUARDED_BRIND,
+  // Software guarded calls for large code model
+  SW_GUARDED_CALL,
+  SW_GUARDED_TAIL,
 
   SF_VC_XV_SE,
   SF_VC_IV_SE,

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -57,6 +57,9 @@ def callseq_end   : SDNode<"ISD::CALLSEQ_END", SDT_CallSeqEnd,
 def riscv_call      : SDNode<"RISCVISD::CALL", SDT_RISCVCall,
                              [SDNPHasChain, SDNPOptInGlue, SDNPOutGlue,
                               SDNPVariadic]>;
+def riscv_sw_guarded_call : SDNode<"RISCVISD::SW_GUARDED_CALL", SDT_RISCVCall,
+                                   [SDNPHasChain, SDNPOptInGlue, SDNPOutGlue,
+                                    SDNPVariadic]>;
 def riscv_ret_glue  : SDNode<"RISCVISD::RET_GLUE", SDTNone,
                              [SDNPHasChain, SDNPOptInGlue, SDNPVariadic]>;
 def riscv_sret_glue : SDNode<"RISCVISD::SRET_GLUE", SDTNone,
@@ -69,6 +72,9 @@ def riscv_brcc      : SDNode<"RISCVISD::BR_CC", SDT_RISCVBrCC,
 def riscv_tail      : SDNode<"RISCVISD::TAIL", SDT_RISCVCall,
                              [SDNPHasChain, SDNPOptInGlue, SDNPOutGlue,
                               SDNPVariadic]>;
+def riscv_sw_guarded_tail : SDNode<"RISCVISD::SW_GUARDED_TAIL", SDT_RISCVCall,
+                                   [SDNPHasChain, SDNPOptInGlue, SDNPOutGlue,
+                                    SDNPVariadic]>;
 def riscv_sw_guarded_brind : SDNode<"RISCVISD::SW_GUARDED_BRIND",
                                     SDTBrind, [SDNPHasChain]>;
 def riscv_sllw      : SDNode<"RISCVISD::SLLW", SDT_RISCVIntBinOpW>;
@@ -1555,10 +1561,15 @@ let Predicates = [NoStdExtZicfilp] in
 def PseudoCALLIndirect : Pseudo<(outs), (ins GPRJALR:$rs1),
                                 [(riscv_call GPRJALR:$rs1)]>,
                          PseudoInstExpansion<(JALR X1, GPR:$rs1, 0)>;
-let Predicates = [HasStdExtZicfilp] in
+let Predicates = [HasStdExtZicfilp] in {
 def PseudoCALLIndirectNonX7 : Pseudo<(outs), (ins GPRJALRNonX7:$rs1),
                                      [(riscv_call GPRJALRNonX7:$rs1)]>,
                               PseudoInstExpansion<(JALR X1, GPR:$rs1, 0)>;
+// For large code model, non-indirect calls could be software-guarded
+def PseudoCALLIndirectX7 : Pseudo<(outs), (ins GPRX7:$rs1),
+                                  [(riscv_sw_guarded_call GPRX7:$rs1)]>,
+                           PseudoInstExpansion<(JALR X1, GPR:$rs1, 0)>;
+}
 }
 
 let isBarrier = 1, isReturn = 1, isTerminator = 1 in
@@ -1579,10 +1590,15 @@ let Predicates = [NoStdExtZicfilp] in
 def PseudoTAILIndirect : Pseudo<(outs), (ins GPRTC:$rs1),
                                 [(riscv_tail GPRTC:$rs1)]>,
                          PseudoInstExpansion<(JALR X0, GPR:$rs1, 0)>;
-let Predicates = [HasStdExtZicfilp] in
+let Predicates = [HasStdExtZicfilp] in {
 def PseudoTAILIndirectNonX7 : Pseudo<(outs), (ins GPRTCNonX7:$rs1),
                                      [(riscv_tail GPRTCNonX7:$rs1)]>,
                               PseudoInstExpansion<(JALR X0, GPR:$rs1, 0)>;
+// For large code model, non-indirect calls could be software-guarded
+def PseudoTAILIndirectX7 : Pseudo<(outs), (ins GPRX7:$rs1),
+                                  [(riscv_sw_guarded_tail GPRX7:$rs1)]>,
+                           PseudoInstExpansion<(JALR X0, GPR:$rs1, 0)>;
+}
 }
 
 def : Pat<(riscv_tail (iPTR tglobaladdr:$dst)),