From 702e46ed5479a6ada62c679675506fbeeaf90fb7 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 9 Dec 2008 21:19:42 +0000 Subject: Teach BasicAA::getModRefInfo(CallSite, CallSite) some tricks based on readnone/readonly functions. Teach memdep to look past readonly calls when analyzing deps for a readonly call. This allows elimination of a few more calls from 403.gcc: before: 63 gvn - Number of instructions PRE'd 153986 gvn - Number of instructions deleted 50069 gvn - Number of loads deleted after: 63 gvn - Number of instructions PRE'd 153991 gvn - Number of instructions deleted 50069 gvn - Number of loads deleted 5 calls isn't much, but this adds plumbing for the next change. llvm-svn: 60794 --- llvm/lib/Analysis/BasicAliasAnalysis.cpp | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) (limited to 'llvm/lib/Analysis/BasicAliasAnalysis.cpp') diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp index bc30c09217c..944d0e0d375 100644 --- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp +++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp @@ -264,10 +264,8 @@ namespace { const Value *V2, unsigned V2Size); ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); - ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { - return NoAA::getModRefInfo(CS1,CS2); - } - + ModRefResult getModRefInfo(CallSite CS1, CallSite CS2); + /// hasNoModRefInfoForCalls - We can provide mod/ref information against /// non-escaping allocations. virtual bool hasNoModRefInfoForCalls() const { return false; } @@ -352,6 +350,24 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) { } +AliasAnalysis::ModRefResult +BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) { + // If CS1 or CS2 are readnone, they don't interact. + ModRefBehavior CS1B = AliasAnalysis::getModRefBehavior(CS1); + if (CS1B == DoesNotAccessMemory) return NoModRef; + + ModRefBehavior CS2B = AliasAnalysis::getModRefBehavior(CS2); + if (CS2B == DoesNotAccessMemory) return NoModRef; + + // If they both only read from memory, just return ref. + if (CS1B == OnlyReadsMemory && CS2B == OnlyReadsMemory) + return Ref; + + // Otherwise, fall back to NoAA (mod+ref). + return NoAA::getModRefInfo(CS1, CS2); +} + + // alias - Provide a bunch of ad-hoc rules to disambiguate in common cases, such // as array references. Note that this function is heavily tail recursive. // Hopefully we have a smart C++ compiler. :) -- cgit v1.2.3