diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 20 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/trip-count11.ll | 29 |
2 files changed, 43 insertions, 6 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 1ab6a40..f65cf34 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -4844,12 +4844,12 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, // EvaluateExpression adds non-phi values to the CurrentIterVals map. DenseMap<Instruction *, Constant *> NextIterVals; Constant *NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, TD); - if (NextPHI == CurrentIterVals[PN]) - return RetVal = NextPHI; // Stopped evolving! if (NextPHI == 0) return 0; // Couldn't evaluate! NextIterVals[PN] = NextPHI; + bool StoppedEvolving = NextPHI == CurrentIterVals[PN]; + // Also evaluate the other PHI nodes. However, we don't get to stop if we // cease to be able to evaluate one of them or if they stop evolving, // because that doesn't necessarily prevent us from computing PN. @@ -4858,11 +4858,19 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, PHINode *PHI = dyn_cast<PHINode>(I->first); if (!PHI || PHI == PN || PHI->getParent() != Header) continue; Constant *&NextPHI = NextIterVals[PHI]; - if (NextPHI) continue; // Already computed! - - Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); - NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, TD); + if (!NextPHI) { // Not already computed. + Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); + NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, TD); + } + if (NextPHI != I->second) + StoppedEvolving = false; } + + // If all entries in CurrentIterVals == NextIterVals then we can stop + // iterating, the loop can't continue to change. + if (StoppedEvolving) + return RetVal = CurrentIterVals[PN]; + CurrentIterVals.swap(NextIterVals); } } diff --git a/test/Analysis/ScalarEvolution/trip-count11.ll b/test/Analysis/ScalarEvolution/trip-count11.ll new file mode 100644 index 0000000..7191503 --- /dev/null +++ b/test/Analysis/ScalarEvolution/trip-count11.ll @@ -0,0 +1,29 @@ +; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s + +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +@foo.a = internal constant [8 x i32] [i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7], align 16 + +define i32 @foo() nounwind uwtable noinline { +entry: + br label %for.cond + +for.cond: ; preds = %for.inc, %entry + %sum.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] +; CHECK: --> %sum.0 Exits: 28 + %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] + %cmp = icmp ult i32 %i.0, 8 + br i1 %cmp, label %for.inc, label %for.end + +for.inc: ; preds = %for.cond + %idxprom = sext i32 %i.0 to i64 + %arrayidx = getelementptr inbounds [8 x i32]* @foo.a, i64 0, i64 %idxprom + %0 = load i32* %arrayidx, align 4 + %add = add nsw i32 %sum.0, %0 + %inc = add nsw i32 %i.0, 1 + br label %for.cond + +for.end: ; preds = %for.cond + ret i32 %sum.0 +} |