From 3d739fe3756bf67be23c2ca54ec7b04bef89bfe0 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Thu, 30 Apr 2009 20:48:53 +0000 Subject: [PATCH] Add some comments, and tidy up some whitespace. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70510 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ScalarEvolution.h | 3 ++- lib/Analysis/ScalarEvolution.cpp | 12 +++++++----- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index 7404f9c00d9..6ef0b35e35d 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -449,7 +449,8 @@ namespace llvm { SCEVHandle getSCEVAtScope(Value *V, const Loop *L); /// isLoopGuardedByCond - Test whether entry to the loop is protected by - /// a conditional between LHS and RHS. + /// a conditional between LHS and RHS. This is used to help avoid max + /// expressions in loop trip counts. bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, SCEV *LHS, SCEV *RHS); diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 252eabe2f26..fbfb0308e34 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2986,8 +2986,9 @@ SCEVHandle ScalarEvolution::HowFarToNonZero(SCEV *V, const Loop *L) { /// BasicBlock * ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) { - // If the block has a unique predecessor, the predecessor must have - // no other successors from which BB is reachable. + // If the block has a unique predecessor, then there is no path from the + // predecessor to the block that does not go through the direct edge + // from the predecessor to the block. if (BasicBlock *Pred = BB->getSinglePredecessor()) return Pred; @@ -3002,10 +3003,11 @@ ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) { } /// isLoopGuardedByCond - Test whether entry to the loop is protected by -/// a conditional between LHS and RHS. +/// a conditional between LHS and RHS. This is used to help avoid max +/// expressions in loop trip counts. bool ScalarEvolution::isLoopGuardedByCond(const Loop *L, - ICmpInst::Predicate Pred, - SCEV *LHS, SCEV *RHS) { + ICmpInst::Predicate Pred, + SCEV *LHS, SCEV *RHS) { BasicBlock *Preheader = L->getLoopPreheader(); BasicBlock *PreheaderDest = L->getHeader(); -- 2.34.1