From 57bbfcec9172face0ffca2c1922d57d3d140bd43 Mon Sep 17 00:00:00 2001 From: John Criswell Date: Wed, 20 Oct 2004 14:38:39 +0000 Subject: [PATCH] Small performance improvement in generated C code: Instead of unconditionally copying all phi node values into temporaries for all successor blocks, generate code that will determine what successor block will be called and then copy only those phi node values needed by the successor block. This seems to cut down namd execution time from being 8% higher than GCC to 4% higher than GCC. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17144 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/CBackend/CBackend.cpp | 24 +++++++++++++++++++++++- lib/Target/CBackend/Writer.cpp | 24 +++++++++++++++++++++++- 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp index 9e835f6093b..7af9bfe4fa6 100644 --- a/lib/Target/CBackend/CBackend.cpp +++ b/lib/Target/CBackend/CBackend.cpp @@ -204,6 +204,8 @@ namespace { } bool isGotoCodeNecessary(BasicBlock *From, BasicBlock *To); + void printPHICopiesForSuccessor(BasicBlock *CurBlock, + BasicBlock *Successor, unsigned Indent); void printPHICopiesForSuccessors(BasicBlock *CurBlock, unsigned Indent); void printBranchToBlock(BasicBlock *CurBlock, BasicBlock *SuccBlock, @@ -1230,6 +1232,23 @@ bool CWriter::isGotoCodeNecessary(BasicBlock *From, BasicBlock *To) { return false; } +void CWriter::printPHICopiesForSuccessor (BasicBlock *CurBlock, + BasicBlock *Successor, + unsigned Indent) { + for (BasicBlock::iterator I = Successor->begin(); isa(I); ++I) { + PHINode *PN = cast(I); + // Now we have to do the printing. + Value *IV = PN->getIncomingValueForBlock(CurBlock); + if (!isa(IV)) { + Out << std::string(Indent, ' '); + Out << " " << Mang->getValueName(I) << "__PHI_TEMPORARY = "; + writeOperand(IV); + Out << "; /* for PHI node */\n"; + } + } +} + + void CWriter::printPHICopiesForSuccessors(BasicBlock *CurBlock, unsigned Indent) { for (succ_iterator SI = succ_begin(CurBlock), E = succ_end(CurBlock); @@ -1261,7 +1280,6 @@ void CWriter::printBranchToBlock(BasicBlock *CurBB, BasicBlock *Succ, // that immediately succeeds the current one. // void CWriter::visitBranchInst(BranchInst &I) { - printPHICopiesForSuccessors(I.getParent(), 0); if (I.isConditional()) { if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(0))) { @@ -1269,10 +1287,12 @@ void CWriter::visitBranchInst(BranchInst &I) { writeOperand(I.getCondition()); Out << ") {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(0), 2); printBranchToBlock(I.getParent(), I.getSuccessor(0), 2); if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(1))) { Out << " } else {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(1), 2); printBranchToBlock(I.getParent(), I.getSuccessor(1), 2); } } else { @@ -1281,11 +1301,13 @@ void CWriter::visitBranchInst(BranchInst &I) { writeOperand(I.getCondition()); Out << ") {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(1), 2); printBranchToBlock(I.getParent(), I.getSuccessor(1), 2); } Out << " }\n"; } else { + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(0), 0); printBranchToBlock(I.getParent(), I.getSuccessor(0), 0); } Out << "\n"; diff --git a/lib/Target/CBackend/Writer.cpp b/lib/Target/CBackend/Writer.cpp index 9e835f6093b..7af9bfe4fa6 100644 --- a/lib/Target/CBackend/Writer.cpp +++ b/lib/Target/CBackend/Writer.cpp @@ -204,6 +204,8 @@ namespace { } bool isGotoCodeNecessary(BasicBlock *From, BasicBlock *To); + void printPHICopiesForSuccessor(BasicBlock *CurBlock, + BasicBlock *Successor, unsigned Indent); void printPHICopiesForSuccessors(BasicBlock *CurBlock, unsigned Indent); void printBranchToBlock(BasicBlock *CurBlock, BasicBlock *SuccBlock, @@ -1230,6 +1232,23 @@ bool CWriter::isGotoCodeNecessary(BasicBlock *From, BasicBlock *To) { return false; } +void CWriter::printPHICopiesForSuccessor (BasicBlock *CurBlock, + BasicBlock *Successor, + unsigned Indent) { + for (BasicBlock::iterator I = Successor->begin(); isa(I); ++I) { + PHINode *PN = cast(I); + // Now we have to do the printing. + Value *IV = PN->getIncomingValueForBlock(CurBlock); + if (!isa(IV)) { + Out << std::string(Indent, ' '); + Out << " " << Mang->getValueName(I) << "__PHI_TEMPORARY = "; + writeOperand(IV); + Out << "; /* for PHI node */\n"; + } + } +} + + void CWriter::printPHICopiesForSuccessors(BasicBlock *CurBlock, unsigned Indent) { for (succ_iterator SI = succ_begin(CurBlock), E = succ_end(CurBlock); @@ -1261,7 +1280,6 @@ void CWriter::printBranchToBlock(BasicBlock *CurBB, BasicBlock *Succ, // that immediately succeeds the current one. // void CWriter::visitBranchInst(BranchInst &I) { - printPHICopiesForSuccessors(I.getParent(), 0); if (I.isConditional()) { if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(0))) { @@ -1269,10 +1287,12 @@ void CWriter::visitBranchInst(BranchInst &I) { writeOperand(I.getCondition()); Out << ") {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(0), 2); printBranchToBlock(I.getParent(), I.getSuccessor(0), 2); if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(1))) { Out << " } else {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(1), 2); printBranchToBlock(I.getParent(), I.getSuccessor(1), 2); } } else { @@ -1281,11 +1301,13 @@ void CWriter::visitBranchInst(BranchInst &I) { writeOperand(I.getCondition()); Out << ") {\n"; + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(1), 2); printBranchToBlock(I.getParent(), I.getSuccessor(1), 2); } Out << " }\n"; } else { + printPHICopiesForSuccessor (I.getParent(), I.getSuccessor(0), 0); printBranchToBlock(I.getParent(), I.getSuccessor(0), 0); } Out << "\n"; -- 2.34.1