From 8c52938e44c6eacfee5faf7103e567f79fa5ebef Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Fri, 1 Jun 2007 07:41:07 +0000 Subject: [PATCH] Ifcvt triangle: don't ifcvt 'true' BB if it has other predecessors; don't merge 'false' BB if it has other predecessors. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37382 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/IfConversion.cpp | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp index 0b2e42f1ff8..77604dd8bcf 100644 --- a/lib/CodeGen/IfConversion.cpp +++ b/lib/CodeGen/IfConversion.cpp @@ -460,14 +460,29 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) { if (!TrueBBI.isPredicable) return false; + // FIXME: Consider duplicating if BB is small. + if (BBI.TrueBB->pred_size() > 1) + return false; + // Predicate the 'true' block after removing its branch. TrueBBI.NonPredSize -= TII->RemoveBranch(*BBI.TrueBB); PredicateBlock(TrueBBI, BBI.BrCond); - // Join the 'true' and 'false' blocks by copying the instructions - // from the 'false' block to the 'true' block. + // If 'true' block has a 'false' successor, add a early exit branch to it. + if (TrueBBI.FalseBB) { + std::vector RevCond(TrueBBI.BrCond); + if (TII->ReverseBranchCondition(RevCond)) + assert(false && "Unable to reverse branch condition!"); + TII->InsertBranch(*BBI.TrueBB, TrueBBI.FalseBB, NULL, RevCond); + } + + // Join the 'true' and 'false' blocks if the 'false' block has no other + // predecessors. Otherwise, add a unconditional branch from 'true' to 'false'. BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()]; - MergeBlocks(TrueBBI, FalseBBI); + if (FalseBBI.BB->pred_size() == 2) + MergeBlocks(TrueBBI, FalseBBI); + else + InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII); // Now merge the entry of the triangle with the true block. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); -- 2.34.1