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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2012-03-28 14:50:09 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2012-03-28 14:50:09 +0000 |
| commit | c1ea16ec4339a9746f436c6f2f5b08197f309343 (patch) | |
| tree | 6fc94a8a0bda0fddeee448e76ce7f5ad98cd16b6 /lib/Transforms/IPO/GlobalOpt.cpp | |
| parent | 9b58464330f45dcf6fe621a40f4bc8617169586e (diff) | |
| download | external_llvm-c1ea16ec4339a9746f436c6f2f5b08197f309343.zip external_llvm-c1ea16ec4339a9746f436c6f2f5b08197f309343.tar.gz external_llvm-c1ea16ec4339a9746f436c6f2f5b08197f309343.tar.bz2 | |
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153576 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/IPO/GlobalOpt.cpp')
| -rw-r--r-- | lib/Transforms/IPO/GlobalOpt.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index a32e550..1522aa4 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -341,6 +341,12 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init, dyn_cast_or_null<ConstantExpr>(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<ConstantAggregateZero>(Init) && GEP->isInBounds()) + SubInit = Constant::getNullValue(GEP->getType()->getElementType()); } Changed |= CleanupConstantGlobalUsers(GEP, SubInit, TD, TLI); |