From 402142e821f2d19e0436dd37adb5890a9c134dea Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sat, 27 Jun 2009 05:16:57 +0000 Subject: When a value is used multiple times within a single PHI, instructions inserted to replace that value must dominate all of of the basic blocks associated with the uses of the value in the PHI, not just one of them. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74376 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/IndVarSimplify.cpp | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'lib/Transforms') diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index d2ba256..27e377f 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -70,6 +70,7 @@ namespace { IVUsers *IU; LoopInfo *LI; ScalarEvolution *SE; + DominatorTree *DT; bool Changed; public: @@ -329,6 +330,7 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) { IU = &getAnalysis(); LI = &getAnalysis(); SE = &getAnalysis(); + DT = &getAnalysis(); Changed = false; // If there are any floating-point recurrences, attempt to @@ -479,12 +481,22 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType, if (!AR->isLoopInvariant(L) && !Stride->isLoopInvariant(L)) continue; + // Determine the insertion point for this user. By default, insert + // immediately before the user. The SCEVExpander class will automatically + // hoist loop invariants out of the loop. For PHI nodes, there may be + // multiple uses, so compute the nearest common dominator for the + // incoming blocks. Instruction *InsertPt = User; if (PHINode *PHI = dyn_cast(InsertPt)) - for (unsigned i = 0; ; ++i) + for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) if (PHI->getIncomingValue(i) == Op) { - InsertPt = PHI->getIncomingBlock(i)->getTerminator(); - break; + if (InsertPt == User) + InsertPt = PHI->getIncomingBlock(i)->getTerminator(); + else + InsertPt = + DT->findNearestCommonDominator(InsertPt->getParent(), + PHI->getIncomingBlock(i)) + ->getTerminator(); } // Now expand it into actual Instructions and patch it into place. -- cgit v1.1