If converter was being too cute. It look for root BBs (which don't have

successors) and use inverse depth first search to traverse the BBs. However
that doesn't work when the CFG has infinite loops. Simply do a linear
traversal of all BBs work just fine.

rdar://9344645


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130324 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 18 deletions

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index db53b0473a..790200b8df 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -27,7 +27,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
@@ -146,10 +145,6 @@ namespace {
         : BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
     };
 
-    /// Roots - Basic blocks that do not have successors. These are the starting
-    /// points of Graph traversal.
-    std::vector<MachineBasicBlock*> Roots;
-
     /// BBAnalysis - Results of if-conversion feasibility analysis indexed by
     /// basic block number.
     std::vector<BBInfo> BBAnalysis;
@@ -287,11 +282,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
   MF.RenumberBlocks();
   BBAnalysis.resize(MF.getNumBlockIDs());
 
-  // Look for root nodes, i.e. blocks without successors.
-  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
-    if (I->succ_empty())
-      Roots.push_back(I);
-
   std::vector<IfcvtToken*> Tokens;
   MadeChange = false;
   unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
@@ -406,7 +396,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
   }
 
   Tokens.clear();
-  Roots.clear();
   BBAnalysis.clear();
 
   if (MadeChange && IfCvtBranchFold) {
@@ -924,13 +913,9 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
 /// candidates.
 void IfConverter::AnalyzeBlocks(MachineFunction &MF,
                                 std::vector<IfcvtToken*> &Tokens) {
-  std::set<MachineBasicBlock*> Visited;
-  for (unsigned i = 0, e = Roots.size(); i != e; ++i) {
-    for (idf_ext_iterator<MachineBasicBlock*> I=idf_ext_begin(Roots[i],Visited),
-           E = idf_ext_end(Roots[i], Visited); I != E; ++I) {
-      MachineBasicBlock *BB = *I;
-      AnalyzeBlock(BB, Tokens);
-    }
+  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
+    MachineBasicBlock *BB = I;
+    AnalyzeBlock(BB, Tokens);
   }
 
   // Sort to favor more complex ifcvt scheme.