diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index 0622b170c8c..728e20e0cff 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -39,10 +39,10 @@ #include "llvm/Transforms/Scalar.h" #include "llvm/BasicBlock.h" -#include "llvm/Constant.h" +#include "llvm/Constants.h" #include "llvm/Instructions.h" #include "llvm/Type.h" -#include "llvm/Analysis/ScalarEvolution.h" +#include "llvm/Analysis/ScalarEvolutionExpressions.h" #include "llvm/Analysis/LoopInfo.h" #include "llvm/Support/CFG.h" #include "llvm/Transforms/Utils/Local.h" @@ -85,7 +85,7 @@ namespace { void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader, std::set &DeadInsts); void LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, - Value *IndVar, ScalarEvolutionRewriter &RW); + ScalarEvolutionRewriter &RW); void RewriteLoopExitValues(Loop *L); void DeleteTriviallyDeadInstructions(std::set &Insts); @@ -177,12 +177,11 @@ void IndVarSimplify::EliminatePointerRecurrence(PHINode *PN, } /// LinearFunctionTestReplace - This method rewrites the exit condition of the -/// loop to be a canonical != comparison against the loop induction variable. -/// This pass is able to rewrite the exit tests of any loop where the SCEV -/// analysis can determine the trip count of the loop, which is actually a much -/// broader range than just linear tests. +/// loop to be a canonical != comparison against the incremented loop induction +/// variable. This pass is able to rewrite the exit tests of any loop where the +/// SCEV analysis can determine a loop-invariant trip count of the loop, which +/// is actually a much broader range than just linear tests. void IndVarSimplify::LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, - Value *IndVar, ScalarEvolutionRewriter &RW) { // Find the exit block for the loop. We can currently only handle loops with // a single exit. @@ -210,9 +209,17 @@ void IndVarSimplify::LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, if (Instruction *Cond = dyn_cast(BI->getCondition())) InstructionsToDelete.insert(Cond); + // The IterationCount expression contains the number of times that the + // backedge actually branches to the loop header. This is one less than the + // number of times the loop executes, so add one to it. + Constant *OneC = ConstantInt::get(IterationCount->getType(), 1); + SCEVHandle TripCount=SCEVAddExpr::get(IterationCount, SCEVUnknown::get(OneC)); + + Value *IndVar = L->getCanonicalInductionVariableIncrement(); + // Expand the code for the iteration count into the preheader of the loop. BasicBlock *Preheader = L->getLoopPreheader(); - Value *ExitCnt = RW.ExpandCodeFor(IterationCount, Preheader->getTerminator(), + Value *ExitCnt = RW.ExpandCodeFor(TripCount, Preheader->getTerminator(), IndVar->getType()); // Insert a new setne or seteq instruction before the branch. @@ -368,7 +375,7 @@ void IndVarSimplify::runOnLoop(Loop *L) { Changed = true; if (!isa(IterationCount)) - LinearFunctionTestReplace(L, IterationCount, IndVar, Rewriter); + LinearFunctionTestReplace(L, IterationCount, Rewriter); #if 0 // If there were induction variables of other sizes, cast the primary