From 1b0f79de0af2b9c0cf71b4aa4d33cef039635897 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Thu, 31 Jan 2013 02:40:59 +0000 Subject: Move isKnownNonNull out of AliasAnalysis.h and into ValueTracking.cpp since it isn't really an AliasAnalysis concept, and ValueTracking has similar things that it could plausibly share code with some day. llvm-svn: 174027 --- llvm/lib/Analysis/ValueTracking.cpp | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'llvm/lib/Analysis/ValueTracking.cpp') diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 473ebc86174..8e3994e8f52 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -2014,3 +2014,19 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V, return false; // Misc instructions which have effects } } + +/// isKnownNonNull - Return true if we know that the specified value is never +/// null. +bool llvm::isKnownNonNull(const Value *V) { + // Alloca never returns null, malloc might. + if (isa(V)) return true; + + // A byval argument is never null. + if (const Argument *A = dyn_cast(V)) + return A->hasByValAttr(); + + // Global values are not null unless extern weak. + if (const GlobalValue *GV = dyn_cast(V)) + return !GV->hasExternalWeakLinkage(); + return false; +} -- cgit v1.2.3