diff options
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/Analysis/ScalarEvolution/sext-to-zext.ll | 23 |
2 files changed, 28 insertions, 4 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 1cb39f65e8b..0365862cc16 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -1612,10 +1612,6 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, void *IP = nullptr; if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; - // If the input value is provably positive, build a zext instead. - if (isKnownNonNegative(Op)) - return getZeroExtendExpr(Op, Ty); - // sext(trunc(x)) --> sext(x) or x or trunc(x) if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { // It's possible the bits taken off by the truncate were all sign bits. If @@ -1781,6 +1777,11 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, } } + // If the input value is provably positive and we could not simplify + // away the sext build a zext instead. + if (isKnownNonNegative(Op)) + return getZeroExtendExpr(Op, Ty); + // The cast wasn't folded; create an explicit cast node. // Recompute the insert position, as it may have been invalidated. if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; diff --git a/llvm/test/Analysis/ScalarEvolution/sext-to-zext.ll b/llvm/test/Analysis/ScalarEvolution/sext-to-zext.ll new file mode 100644 index 00000000000..ca9c6de0d50 --- /dev/null +++ b/llvm/test/Analysis/ScalarEvolution/sext-to-zext.ll @@ -0,0 +1,23 @@ +; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s + +define void @f(i1 %c) { +; CHECK-LABEL: Classifying expressions for: @f +entry: + %start = select i1 %c, i32 100, i32 0 + %step = select i1 %c, i32 -1, i32 1 + br label %loop + +loop: + %iv = phi i32 [ %start, %entry ], [ %iv.dec, %loop ] + %iv.tc = phi i32 [ 0, %entry ], [ %iv.tc.inc, %loop ] + %iv.tc.inc = add i32 %iv.tc, 1 + %iv.dec = add nsw i32 %iv, %step + %iv.sext = sext i32 %iv to i64 +; CHECK: %iv.sext = sext i32 %iv to i64 +; CHECK-NEXT: --> {(sext i32 %start to i64),+,(sext i32 %step to i64)}<nsw><%loop> + %be = icmp ne i32 %iv.tc.inc, 100 + br i1 %be, label %loop, label %leave + +leave: + ret void +} |
