diff options
author | Dorit Nuzman <dorit.nuzman@intel.com> | 2017-12-10 11:13:35 +0000 |
---|---|---|
committer | Dorit Nuzman <dorit.nuzman@intel.com> | 2017-12-10 11:13:35 +0000 |
commit | 6ae5d1f67fd8f26fd1a007667b8615035b89a524 (patch) | |
tree | fb5849d5fb905a7dba8cc7c9a319c311e7346d28 /lib/Analysis/ScalarEvolution.cpp | |
parent | 9b5897c93f202f92b7f6e0b59dccabd820502b8b (diff) |
[SCEV] Fix wrong Equal predicate created in getAddRecForPhiWithCasts
CreateAddRecFromPHIWithCastsImpl() adds an IncrementNUSW overflow predicate
which allows the PSCEV rewriter to rewrite this scev expression:
(zext i8 {0, + , (trunc i32 step to i8)} to i32)
into
{0, +, (sext i8 (trunc i32 step to i8) to i32)}
But then it adds the wrong Equal predicate:
%step == (zext i8 (trunc i32 %step to i8) to i32).
instead of:
%step == (sext i8 (trunc i32 %step to i8) to i32)
This is fixed here.
Differential Revision: https://reviews.llvm.org/D40641
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320298 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
-rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 3ed7dde47bb..960bd64830c 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -4636,18 +4636,19 @@ ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy) // for each of StartVal and Accum - auto GetExtendedExpr = [&](const SCEV *Expr) -> const SCEV * { + auto getExtendedExpr = [&](const SCEV *Expr, + bool CreateSignExtend) -> const SCEV * { assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant"); const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy); const SCEV *ExtendedExpr = - Signed ? getSignExtendExpr(TruncatedExpr, Expr->getType()) - : getZeroExtendExpr(TruncatedExpr, Expr->getType()); + CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType()) + : getZeroExtendExpr(TruncatedExpr, Expr->getType()); return ExtendedExpr; }; // Given: // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy - // = GetExtendedExpr(Expr) + // = getExtendedExpr(Expr) // Determine whether the predicate P: Expr == ExtendedExpr // is known to be false at compile time auto PredIsKnownFalse = [&](const SCEV *Expr, @@ -4656,13 +4657,15 @@ ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr); }; - const SCEV *StartExtended = GetExtendedExpr(StartVal); + const SCEV *StartExtended = getExtendedExpr(StartVal, Signed); if (PredIsKnownFalse(StartVal, StartExtended)) { DEBUG(dbgs() << "P2 is compile-time false\n";); return None; } - const SCEV *AccumExtended = GetExtendedExpr(Accum); + // The Step is always Signed (because the overflow checks are either + // NSSW or NUSW) + const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true); if (PredIsKnownFalse(Accum, AccumExtended)) { DEBUG(dbgs() << "P3 is compile-time false\n";); return None; |