From aa9e4a5e590985f9e58a1efb83cb5cb10964fbbf Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Wed, 28 Mar 2012 14:50:09 +0000 Subject: GlobalOpt: If we have an inbounds GEP from a ConstantAggregateZero global that we just determined to be constant, replace all loads from it with a zero value. llvm-svn: 153576 --- llvm/lib/Transforms/IPO/GlobalOpt.cpp | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp index a32e5509545..1522aa408b6 100644 --- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp +++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp @@ -341,6 +341,12 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init, dyn_cast_or_null(ConstantFoldInstruction(GEP, TD, TLI)); if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr) SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); + + // If the initializer is an all-null value and we have an inbounds GEP, + // we already know what the result of any load from that GEP is. + // TODO: Handle splats. + if (Init && isa(Init) && GEP->isInBounds()) + SubInit = Constant::getNullValue(GEP->getType()->getElementType()); } Changed |= CleanupConstantGlobalUsers(GEP, SubInit, TD, TLI); -- cgit v1.2.3