[PATCH] [SDAG] Don't pass inline asm blobs through ExternalSymbolSDNodes

[Reid Kleckner]

Hi echristo,

Shoving the string through the ExternalSymbol uniquing hash tables is a
waste of time. Instead, just point at the InlineAsm value from the IR,
and pull the string out later when we lower to MI.

http://reviews.llvm.org/D9575

Files:
  lib/CodeGen/SelectionDAG/InstrEmitter.cpp
  lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

Index: lib/CodeGen/SelectionDAG/InstrEmitter.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -940,8 +940,8 @@
 
     // Add the asm string as an external symbol operand.
     SDValue AsmStrV = Node->getOperand(InlineAsm::Op_AsmString);
-    const char *AsmStr = cast<ExternalSymbolSDNode>(AsmStrV)->getSymbol();
-    MIB.addExternalSymbol(AsmStr);
+    const Value *SrcVal = cast<SrcValueSDNode>(AsmStrV)->getValue();
+    MIB.addExternalSymbol(cast<InlineAsm>(SrcVal)->getAsmString().c_str());
 
     // Add the HasSideEffect, isAlignStack, AsmDialect, MayLoad and MayStore
     // bits.
Index: lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
===================================================================
--- lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
+++ lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
@@ -67,6 +67,9 @@
       if (isa<BlockAddressSDNode>(Node))   return true;
       if (Node->getOpcode() == ISD::EntryToken ||
           isa<MDNodeSDNode>(Node)) return true;
+      if (auto *SV = dyn_cast<SrcValueSDNode>(Node))
+        if (isa<InlineAsm>(SV->getValue()))
+          return true;
       return false;
     }
 
Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5953,9 +5953,7 @@
   // AsmNodeOperands - The operands for the ISD::INLINEASM node.
   std::vector<SDValue> AsmNodeOperands;
   AsmNodeOperands.push_back(SDValue());  // reserve space for input chain
-  AsmNodeOperands.push_back(
-          DAG.getTargetExternalSymbol(IA->getAsmString().c_str(),
-                                      TLI.getPointerTy()));
+  AsmNodeOperands.push_back(DAG.getSrcValue(IA));
 
   // If we have a !srcloc metadata node associated with it, we want to attach
   // this to the ultimately generated inline asm machineinstr.  To do this, we
Index: lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2574,6 +2574,13 @@
   case ISD::READ_REGISTER: return Select_READ_REGISTER(NodeToMatch);
   case ISD::WRITE_REGISTER: return Select_WRITE_REGISTER(NodeToMatch);
   case ISD::UNDEF:     return Select_UNDEF(NodeToMatch);
+  case ISD::SRCVALUE:
+    // SrcValues wrapping inline asm are leaves and don't need selection.
+    if (isa<InlineAsm>(cast<SrcValueSDNode>(NodeToMatch)->getValue())) {
+      NodeToMatch->setNodeId(-1);
+      return nullptr;
+    }
+    break;
   }
 
   assert(!NodeToMatch->isMachineOpcode() && "Node already selected!");

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