From 495a0b51915eb763576874f29192820b731edc22 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 17 Aug 2005 06:37:43 +0000 Subject: [PATCH] Add a new beta option for critical edge splitting, to avoid a problem that Nate noticed in yacr2 (and I know occurs in other places as well). This is still rough, as the critical edge blocks are not intelligently placed but is added to get some idea to see if this improves performance. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22825 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 23 +++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp index 7303ee2add2..6ba00bccdf8 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp @@ -29,12 +29,18 @@ #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetLowering.h" #include "llvm/Target/TargetMachine.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include #include using namespace llvm; +static cl::opt +SplitPHICritEdges("split-phi-constant-crit-edges", cl::Hidden, + cl::desc("Split critical edges for PHI values that are constants")); + + #ifndef _NDEBUG static cl::opt ViewDAGs("view-isel-dags", cl::Hidden, @@ -959,6 +965,10 @@ unsigned SelectionDAGISel::MakeReg(MVT::ValueType VT) { return RegMap->createVirtualRegister(TLI.getRegClassFor(VT)); } +void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const { + if (!SplitPHICritEdges) + AU.setPreservesAll(); +} bool SelectionDAGISel::runOnFunction(Function &Fn) { @@ -966,6 +976,19 @@ bool SelectionDAGISel::runOnFunction(Function &Fn) { RegMap = MF.getSSARegMap(); DEBUG(std::cerr << "\n\n\n=== " << Fn.getName() << "\n"); + // First pass, split all critical edges for PHI nodes with incoming values + // that are constants, this way the load of the constant into a vreg will not + // be placed into MBBs that are used some other way. + if (SplitPHICritEdges) + for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) { + PHINode *PN; + for (BasicBlock::iterator BBI = BB->begin(); + (PN = dyn_cast(BBI)); ++BBI) + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (isa(PN->getIncomingValue(i))) + SplitCriticalEdge(PN->getIncomingBlock(i), BB); + } + FunctionLoweringInfo FuncInfo(TLI, Fn, MF); for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) -- 2.34.1