From a02bfced06b4cc700e50bc497cc42667653f091a Mon Sep 17 00:00:00 2001 From: Andrew Trick Date: Tue, 11 Oct 2011 02:30:45 +0000 Subject: [PATCH] Add experimental -enable-lsr-phielim option. I'm not sure we will need it in the long run, but the option is currently useful for checking if the output of LSR is "clean". git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141634 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 22 ++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 26fc03b18b6..d03b86a7e9d 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -83,6 +83,12 @@ cl::opt EnableNested( cl::opt EnableRetry( "enable-lsr-retry", cl::Hidden, cl::desc("Enable LSR retry")); + +// Temporary flag to cleanup congruent phis after LSR phi expansion. +// It's currently disabled until we can determine whether it's truly useful or +// not. The flag should be removed after the v3.0 release. +cl::opt EnablePhiElim( + "enable-lsr-phielim", cl::Hidden, cl::desc("Enable LSR phi elimination")); } namespace { @@ -3816,6 +3822,14 @@ LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P) // Skip nested loops until we can model them better with formulae. if (!EnableNested && !L->empty()) { + + if (EnablePhiElim) { + // Remove any extra phis created by processing inner loops. + SmallVector DeadInsts; + SCEVExpander Rewriter(SE, "lsr"); + Changed |= Rewriter.replaceCongruentIVs(L, &DT, DeadInsts); + Changed |= DeleteTriviallyDeadInstructions(DeadInsts); + } DEBUG(dbgs() << "LSR skipping outer loop " << *L << "\n"); return; } @@ -3861,6 +3875,14 @@ LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P) // Now that we've decided what we want, make it so. ImplementSolution(Solution, P); + + if (EnablePhiElim) { + // Remove any extra phis created by processing inner loops. + SmallVector DeadInsts; + SCEVExpander Rewriter(SE, "lsr"); + Changed |= Rewriter.replaceCongruentIVs(L, &DT, DeadInsts); + Changed |= DeleteTriviallyDeadInstructions(DeadInsts); + } } void LSRInstance::print_factors_and_types(raw_ostream &OS) const { -- 2.34.1