[llvm-commits] [llvm] r130324 - in /llvm/trunk: lib/CodeGen/IfConversion.cpp test/CodeGen/ARM/2011-04-27-IfCvtBug.ll

[Evan Cheng]

Author: evancheng
Date: Wed Apr 27 14:32:43 2011
New Revision: 130324

URL: http://llvm.org/viewvc/llvm-project?rev=130324&view=rev
Log:
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

Added:
    llvm/trunk/test/CodeGen/ARM/2011-04-27-IfCvtBug.ll
Modified:
    llvm/trunk/lib/CodeGen/IfConversion.cpp

Modified: llvm/trunk/lib/CodeGen/IfConversion.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/IfConversion.cpp?rev=130324&r1=130323&r2=130324&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/IfConversion.cpp (original)
+++ llvm/trunk/lib/CodeGen/IfConversion.cpp Wed Apr 27 14:32:43 2011
@@ -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 @@
         : 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 @@
   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 @@
   }
 
   Tokens.clear();
-  Roots.clear();
   BBAnalysis.clear();
 
   if (MadeChange && IfCvtBranchFold) {
@@ -924,13 +913,9 @@
 /// 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.

Added: llvm/trunk/test/CodeGen/ARM/2011-04-27-IfCvtBug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/2011-04-27-IfCvtBug.ll?rev=130324&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/2011-04-27-IfCvtBug.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/2011-04-27-IfCvtBug.ll Wed Apr 27 14:32:43 2011
@@ -0,0 +1,59 @@
+; RUN: llc < %s -mtriple=thumbv7-apple-ios
+
+; 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
+
+%struct.hc = type { i32, i32, i32, i32 }
+
+define i32 @t(i32 %type) optsize {
+entry:
+  br i1 undef, label %if.then, label %if.else
+
+if.then:
+  unreachable
+
+if.else:
+  br i1 undef, label %if.then15, label %if.else18
+
+if.then15:
+  unreachable
+
+if.else18:
+  switch i32 %type, label %if.else173 [
+    i32 3, label %if.then115
+    i32 1, label %if.then102
+  ]
+
+if.then102:
+  br i1 undef, label %cond.true10.i, label %t.exit
+
+cond.true10.i:
+  br label %t.exit
+
+t.exit:
+  unreachable
+
+if.then115:
+  br i1 undef, label %if.else163, label %if.else145
+
+if.else145:
+  %call150 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34865152) optsize
+  br label %while.body172
+
+if.else163:
+  %call168 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34078720) optsize
+  br label %while.body172
+
+while.body172:
+  br label %while.body172
+
+if.else173:
+  ret i32 -1
+}
+
+declare hidden fastcc %struct.hc* @foo(%struct.hc* nocapture, i32) nounwind optsize
+