From cc030b7e514d2596e296c58095efd4cce9a76631 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Fri, 26 Jun 2009 22:36:20 +0000 Subject: Fix ScalarEvolution::getAddRecExpr's code which canonicalized the nesting order of nested AddRec expressions to skip the transformation if it would introduce an AddRec with operands not loop-invariant with respect to its loop. llvm-svn: 74343 --- llvm/lib/Analysis/ScalarEvolution.cpp | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) (limited to 'llvm/lib') diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 2d8bd7d53a6..dcb179afd23 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -1651,8 +1651,29 @@ ScalarEvolution::getAddRecExpr(SmallVectorImpl &Operands, SmallVector NestedOperands(NestedAR->op_begin(), NestedAR->op_end()); Operands[0] = NestedAR->getStart(); - NestedOperands[0] = getAddRecExpr(Operands, L); - return getAddRecExpr(NestedOperands, NestedLoop); + // AddRecs require their operands be loop-invariant with respect to their + // loops. Don't perform this transformation if it would break this + // requirement. + bool AllInvariant = true; + for (unsigned i = 0, e = Operands.size(); i != e; ++i) + if (!Operands[i]->isLoopInvariant(L)) { + AllInvariant = false; + break; + } + if (AllInvariant) { + NestedOperands[0] = getAddRecExpr(Operands, L); + AllInvariant = true; + for (unsigned i = 0, e = NestedOperands.size(); i != e; ++i) + if (!NestedOperands[i]->isLoopInvariant(NestedLoop)) { + AllInvariant = false; + break; + } + if (AllInvariant) + // Ok, both add recurrences are valid after the transformation. + return getAddRecExpr(NestedOperands, NestedLoop); + } + // Reset Operands to its original state. + Operands[0] = NestedAR; } } -- cgit v1.2.3