Changes in directory llvm/lib/CodeGen:
IfConversion.cpp updated: 1.31 -> 1.32 --- Log message: If a unconditional branch is added to branch to the false path during ifcvt, the predicated block cannot be iteratively ifcvted. --- Diffs of the changes: (+33 -6) IfConversion.cpp | 39 +++++++++++++++++++++++++++++++++------ 1 files changed, 33 insertions(+), 6 deletions(-) Index: llvm/lib/CodeGen/IfConversion.cpp diff -u llvm/lib/CodeGen/IfConversion.cpp:1.31 llvm/lib/CodeGen/IfConversion.cpp:1.32 --- llvm/lib/CodeGen/IfConversion.cpp:1.31 Tue Jun 5 20:12:44 2007 +++ llvm/lib/CodeGen/IfConversion.cpp Tue Jun 5 21:08:52 2007 @@ -165,8 +165,8 @@ RetVal = IfConvertSimple(BBI); DOUT << (RetVal ? "succeeded!" : "failed!") << "\n"; if (RetVal) - if (isRev) NumSimple++; - else NumSimpleRev++; + if (isRev) NumSimpleRev++; + else NumSimple++; break; } case ICTriangle: @@ -515,12 +515,25 @@ // to the 'false' branch. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); MergeBlocks(BBI, *CvtBBI); - if (!isNextBlock(BBI.BB, NextBBI->BB)) + bool IterIfcvt = true; + if (!isNextBlock(BBI.BB, NextBBI->BB)) { + // Now ifcvt'd block will look like this: + // BB: + // ... + // t, f = cmp + // if t op + // b BBf + // + // We cannot further ifcvt this block because the unconditional branch will + // have to be predicated on the new condition, that will not be available + // if cmp executes. InsertUncondBranch(BBI.BB, NextBBI->BB, TII); + } std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate)); // Update block info. BB can be iteratively if-converted. - BBI.Kind = ICReAnalyze; + if (IterIfcvt) + BBI.Kind = ICReAnalyze; ReTryPreds(BBI.BB); CvtBBI->Kind = ICDead; @@ -552,11 +565,24 @@ // predecessors. Otherwise, add a unconditional branch from 'true' to 'false'. BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()]; bool FalseBBDead = false; + bool IterIfcvt = true; if (!HasEarlyExit && FalseBBI.BB->pred_size() == 2) { MergeBlocks(TrueBBI, FalseBBI); FalseBBDead = true; - } else if (!isNextBlock(TrueBBI.BB, FalseBBI.BB)) + } else if (!isNextBlock(TrueBBI.BB, FalseBBI.BB)) { InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII); + // Now ifcvt'd block will look like this: + // BB: + // ... + // t, f = cmp + // if t op + // b BBf + // + // We cannot further ifcvt this block because the unconditional branch will + // have to be predicated on the new condition, that will not be available + // if cmp executes. + IterIfcvt = false; + } // Now merge the entry of the triangle with the true block. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); @@ -565,7 +591,8 @@ std::back_inserter(BBI.Predicate)); // Update block info. BB can be iteratively if-converted. - BBI.Kind = ICReAnalyze; + if (IterIfcvt) + BBI.Kind = ICReAnalyze; ReTryPreds(BBI.BB); TrueBBI.Kind = ICDead; if (FalseBBDead) _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits