diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 10 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/2008-02-12-SMAXTripCount.ll | 16 |
2 files changed, 20 insertions, 6 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 122dba3..65cee82 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2527,19 +2527,17 @@ HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L, bool isSigned) { if (AddRec->isAffine()) { // The number of iterations for "{n,+,1} < m", is m-n. However, we don't // know that m is >= n on input to the loop. If it is, the condition - // returns true zero times. To handle both cases, we return SMAX(0, m-n). + // returns true zero times. To handle both cases, we return SMAX(m, n)-n. // FORNOW: We only support unit strides. SCEVHandle One = SE.getIntegerSCEV(1, RHS->getType()); if (AddRec->getOperand(1) != One) return UnknownValue; - SCEVHandle Iters = SE.getMinusSCEV(RHS, AddRec->getOperand(0)); + SCEVHandle Start = AddRec->getOperand(0); + SCEVHandle End = isSigned ? SE.getSMaxExpr(RHS, Start) : (SCEVHandle)RHS; - if (isSigned) - return SE.getSMaxExpr(SE.getIntegerSCEV(0, RHS->getType()), Iters); - else - return Iters; + return SE.getMinusSCEV(End, Start); } return UnknownValue; diff --git a/test/Analysis/ScalarEvolution/2008-02-12-SMAXTripCount.ll b/test/Analysis/ScalarEvolution/2008-02-12-SMAXTripCount.ll new file mode 100644 index 0000000..292ea99 --- /dev/null +++ b/test/Analysis/ScalarEvolution/2008-02-12-SMAXTripCount.ll @@ -0,0 +1,16 @@ +; RUN: llvm-as < %s | opt -scalar-evolution -analyze | grep {Loop loop: ( 100 + ( -100 smax %n)) iterations!} +; PR2002 + +define void @foo(i8 %n) { +entry: + br label %loop +loop: + %i = phi i8 [ -100, %entry ], [ %i.inc, %next ] + %cond = icmp slt i8 %i, %n + br i1 %cond, label %next, label %return +next: + %i.inc = add i8 %i, 1 + br label %loop +return: + ret void +} |