diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 26 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/max-trip-count.ll | 42 |
2 files changed, 52 insertions, 16 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f5a762af82..b3ddfc032f 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3854,14 +3854,13 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L, else MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max); } else { - // Both conditions must be true for the loop to exit. + // Both conditions must be true at the same time for the loop to exit. + // For now, be conservative. assert(L->contains(FBB) && "Loop block has no successor in loop!"); - if (BTI0.Exact != getCouldNotCompute() && - BTI1.Exact != getCouldNotCompute()) - BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact); - if (BTI0.Max != getCouldNotCompute() && - BTI1.Max != getCouldNotCompute()) - MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max); + if (BTI0.Max == BTI1.Max) + MaxBECount = BTI0.Max; + if (BTI0.Exact == BTI1.Exact) + BECount = BTI0.Exact; } return BackedgeTakenInfo(BECount, MaxBECount); @@ -3889,14 +3888,13 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L, else MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max); } else { - // Both conditions must be false for the loop to exit. + // Both conditions must be false at the same time for the loop to exit. + // For now, be conservative. assert(L->contains(TBB) && "Loop block has no successor in loop!"); - if (BTI0.Exact != getCouldNotCompute() && - BTI1.Exact != getCouldNotCompute()) - BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact); - if (BTI0.Max != getCouldNotCompute() && - BTI1.Max != getCouldNotCompute()) - MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max); + if (BTI0.Max == BTI1.Max) + MaxBECount = BTI0.Max; + if (BTI0.Exact == BTI1.Exact) + BECount = BTI0.Exact; } return BackedgeTakenInfo(BECount, MaxBECount); diff --git a/test/Analysis/ScalarEvolution/max-trip-count.ll b/test/Analysis/ScalarEvolution/max-trip-count.ll index a8966be4cc..843fb07308 100644 --- a/test/Analysis/ScalarEvolution/max-trip-count.ll +++ b/test/Analysis/ScalarEvolution/max-trip-count.ll @@ -1,8 +1,9 @@ -; RUN: opt < %s -analyze -scalar-evolution \ -; RUN: | grep {\{%d,+,\[^\{\}\]\*\}<%bb>} +; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s ; ScalarEvolution should be able to understand the loop and eliminate the casts. +; CHECK: {%d,+,sizeof(i32)} + define void @foo(i32* nocapture %d, i32 %n) nounwind { entry: %0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1] @@ -32,3 +33,40 @@ bb1.return_crit_edge: ; preds = %bb1 return: ; preds = %bb1.return_crit_edge, %entry ret void } + +; ScalarEvolution should be able to find the maximum tripcount +; of this multiple-exit loop, and if it doesn't know the exact +; count, it should say so. + +; PR7845 +; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count. +; CHECK: Loop %for.cond: max backedge-taken count is 5 + +@.str = private constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=2] + +define i32 @main() nounwind { +entry: + br label %for.cond + +for.cond: ; preds = %for.inc, %entry + %g_4.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] ; <i32> [#uses=5] + %cmp = icmp slt i32 %g_4.0, 5 ; <i1> [#uses=1] + br i1 %cmp, label %for.body, label %for.end + +for.body: ; preds = %for.cond + %conv = trunc i32 %g_4.0 to i16 ; <i16> [#uses=1] + %tobool.not = icmp eq i16 %conv, 0 ; <i1> [#uses=1] + %tobool3 = icmp ne i32 %g_4.0, 0 ; <i1> [#uses=1] + %or.cond = and i1 %tobool.not, %tobool3 ; <i1> [#uses=1] + br i1 %or.cond, label %for.end, label %for.inc + +for.inc: ; preds = %for.body + %add = add nsw i32 %g_4.0, 1 ; <i32> [#uses=1] + br label %for.cond + +for.end: ; preds = %for.body, %for.cond + %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str, i64 0, i64 0), i32 %g_4.0) nounwind ; <i32> [#uses=0] + ret i32 0 +} + +declare i32 @printf(i8*, ...) |