From: Dan Gohman Date: Wed, 7 Jul 2010 14:30:04 +0000 (+0000) Subject: Minore code simplification. X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b8c86a010c2d958d6f655b0f66101d8964d7a0fc;p=oota-llvm.git Minore code simplification. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107777 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index d3a67a8eba3..4f53a6d6255 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -763,8 +763,22 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size, if ((isa(O2) && isKnownNonNull(O1)) || (isa(O1) && isKnownNonNull(O2))) return NoAlias; - } + // If one pointer is the result of a call/invoke or load and the other is a + // non-escaping local object within the same function, then we know the + // object couldn't escape to a point where the call could return it. + // + // Note that if the pointers are in different functions, there are a + // variety of complications. A call with a nocapture argument may still + // temporary store the nocapture argument's value in a temporary memory + // location if that memory location doesn't escape. Or it may pass a + // nocapture value to other functions as long as they don't capture it. + if (isEscapeSource(O1) && isNonEscapingLocalObject(O2)) + return NoAlias; + if (isEscapeSource(O2) && isNonEscapingLocalObject(O1)) + return NoAlias; + } + // If the size of one access is larger than the entire object on the other // side, then we know such behavior is undefined and can assume no alias. if (TD) @@ -772,22 +786,6 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size, (V2Size != ~0U && isObjectSmallerThan(O1, V2Size, *TD))) return NoAlias; - // If one pointer is the result of a call/invoke or load and the other is a - // non-escaping local object within the same function, then we know the - // object couldn't escape to a point where the call could return it. - // - // Note that if the pointers are in different functions, there are a - // variety of complications. A call with a nocapture argument may still - // temporary store the nocapture argument's value in a temporary memory - // location if that memory location doesn't escape. Or it may pass a - // nocapture value to other functions as long as they don't capture it. - if (O1 != O2) { - if (isEscapeSource(O1) && isNonEscapingLocalObject(O2)) - return NoAlias; - if (isEscapeSource(O2) && isNonEscapingLocalObject(O1)) - return NoAlias; - } - // FIXME: This isn't aggressively handling alias(GEP, PHI) for example: if the // GEP can't simplify, we don't even look at the PHI cases. if (!isa(V1) && isa(V2)) {