From ba5be5c07bb19dcf484e3aa40cd139dd07c10407 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Tue, 20 Apr 2010 15:00:41 +0000
Subject: [PATCH] Don't send PHI nodes down to SelectionDAGBuilder of FastISel,
 since they end up doing nothing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101904 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/FastISel.cpp            | 8 ++++----
 lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 4 ++++
 lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h   | 2 +-
 lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp    | 2 +-
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index cd72fe7003d..8f53c5caaeb 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -52,6 +52,7 @@
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "FunctionLoweringInfo.h"
 using namespace llvm;
 
@@ -692,10 +693,6 @@ FastISel::SelectOperator(const User *I, unsigned Opcode) {
     // Nothing to emit.
     return true;
 
-  case Instruction::PHI:
-    // PHI nodes are already emitted.
-    return true;
-
   case Instruction::Alloca:
     // FunctionLowering has the static-sized case covered.
     if (StaticAllocaMap.count(cast<AllocaInst>(I)))
@@ -735,6 +732,9 @@ FastISel::SelectOperator(const User *I, unsigned Opcode) {
     return true;
   }
 
+  case Instruction::PHI:
+    llvm_unreachable("FastISel shouldn't visit PHI nodes!");
+
   default:
     // Unhandled instruction. Halt "fast" selection and bail.
     return false;
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 470689bd06f..054174f037e 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -621,6 +621,10 @@ void SelectionDAGBuilder::visit(const Instruction &I) {
   CurDebugLoc = DebugLoc();
 }
 
+void SelectionDAGBuilder::visitPHI(const PHINode &) {
+  llvm_unreachable("SelectionDAGBuilder shouldn't visit PHI nodes!");
+}
+
 void SelectionDAGBuilder::visit(unsigned Opcode, const User &I) {
   // Note: this doesn't use InstVisitor, because it has to work with
   // ConstantExpr's in addition to instructions.
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 1f9e43ff339..ad18850bacd 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -468,7 +468,7 @@ private:
   void visitAlloca(const AllocaInst &I);
   void visitLoad(const LoadInst &I);
   void visitStore(const StoreInst &I);
-  void visitPHI(const PHINode &I) { } // PHI nodes are handled specially.
+  void visitPHI(const PHINode &I);
   void visitCall(const CallInst &I);
   bool visitMemCmpCall(const CallInst &I);
   
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index e21b1c8ca59..2a27d1b59a2 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -728,7 +728,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
     const BasicBlock *LLVMBB = &*I;
     MachineBasicBlock *BB = FuncInfo->MBBMap[LLVMBB];
 
-    BasicBlock::const_iterator const Begin = LLVMBB->begin();
+    BasicBlock::const_iterator const Begin = LLVMBB->getFirstNonPHI();
     BasicBlock::const_iterator const End = LLVMBB->end();
     BasicBlock::const_iterator BI = Begin;
 
-- 
2.34.1