From 5eb301740c4ee5d978535caa917cc004733a7fca Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Mon, 30 Jul 2012 23:45:06 +0000
Subject: [PATCH] Extend the InstVisitor to visit the specialized classes
 wrapping CallInst for intrinsics. This allows users of the InstVisitor that
 would like to special case certain very common intrinsics to do so naturally
 in keeping with the type hierarchy's utility classes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161006 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/InstVisitor.h | 53 ++++++++++++++++++++++++++----
 1 file changed, 46 insertions(+), 7 deletions(-)

diff --git a/include/llvm/Support/InstVisitor.h b/include/llvm/Support/InstVisitor.h
index 52de8f660dd..109b3cff85b 100644
--- a/include/llvm/Support/InstVisitor.h
+++ b/include/llvm/Support/InstVisitor.h
@@ -13,6 +13,8 @@
 
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/IntrinsicInst.h"
 #include "llvm/Module.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -145,14 +147,17 @@ public:
   // visitMul to proxy to visitBinaryOperator for instance in case the user does
   // not need this generality.
   //
-  // The one problem case we have to handle here though is that the PHINode
-  // class and opcode name are the exact same.  Because of this, we cannot
-  // define visitPHINode (the inst version) to forward to visitPHINode (the
-  // generic version) without multiply defined symbols and recursion.  To handle
-  // this, we do not autoexpand "Other" instructions, we do it manually.
-  //
+  // These functions can also implement fan-out, when a single opcode and
+  // instruction have multiple more specific Instruction subclasses. The Call
+  // instruction currently supports this. We implement that by redirecting that
+  // instruction to a special delegation helper.
 #define HANDLE_INST(NUM, OPCODE, CLASS) \
-    RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
+    RetTy visit##OPCODE(CLASS &I) { \
+      if (NUM == Instruction::Call) \
+        return delegateCallInst(I); \
+      else \
+        DELEGATE(CLASS); \
+    }
 #include "llvm/Instruction.def"
 
   // Specific Instruction type classes... note that all of the casts are
@@ -195,6 +200,17 @@ public:
   RetTy visitInsertValueInst(InsertValueInst &I)  { DELEGATE(Instruction); }
   RetTy visitLandingPadInst(LandingPadInst &I)    { DELEGATE(Instruction); }
 
+  // Handle the special instrinsic instruction classes.
+  RetTy visitDbgDeclareInst(DbgDeclareInst &I)    { DELEGATE(DbgInfoIntrinsic);}
+  RetTy visitDbgValueInst(DbgValueInst &I)        { DELEGATE(DbgInfoIntrinsic);}
+  RetTy visitDbgInfoIntrinsic(DbgInfoIntrinsic &I) { DELEGATE(IntrinsicInst); }
+  RetTy visitMemSetInst(MemSetInst &I)            { DELEGATE(MemIntrinsic); }
+  RetTy visitMemCpyInst(MemCpyInst &I)            { DELEGATE(MemTransferInst); }
+  RetTy visitMemMoveInst(MemMoveInst &I)          { DELEGATE(MemTransferInst); }
+  RetTy visitMemTransferInst(MemTransferInst &I)  { DELEGATE(MemIntrinsic); }
+  RetTy visitMemIntrinsic(MemIntrinsic &I)        { DELEGATE(IntrinsicInst); }
+  RetTy visitIntrinsicInst(IntrinsicInst &I)      { DELEGATE(CallInst); }
+
   // Call and Invoke are slightly different as they delegate first through
   // a generic CallSite visitor.
   RetTy visitCallInst(CallInst &I) {
@@ -234,6 +250,29 @@ public:
   // Note that you MUST override this function if your return type is not void.
   //
   void visitInstruction(Instruction &I) {}  // Ignore unhandled instructions
+
+private:
+  // Special helper function to delegate to CallInst subclass visitors.
+  RetTy delegateCallInst(CallInst &I) {
+    if (const Function *F = I.getCalledFunction()) {
+      switch ((Intrinsic::ID)F->getIntrinsicID()) {
+      default:                     DELEGATE(IntrinsicInst);
+      case Intrinsic::dbg_declare: DELEGATE(DbgDeclareInst);
+      case Intrinsic::dbg_value:   DELEGATE(DbgValueInst);
+      case Intrinsic::memcpy:      DELEGATE(MemCpyInst);
+      case Intrinsic::memmove:     DELEGATE(MemMoveInst);
+      case Intrinsic::memset:      DELEGATE(MemSetInst);
+      case Intrinsic::not_intrinsic: break;
+      }
+    }
+    DELEGATE(CallInst);
+  }
+
+  // An overload that will never actually be called, it is used only from dead
+  // code in the dispatching from opcodes to instruction subclasses.
+  RetTy delegateCallInst(Instruction &I) {
+    llvm_unreachable("delegateCallInst called for non-CallInst");
+  }
 };
 
 #undef DELEGATE
-- 
2.34.1