From bd38edfe236944ebecbbf84ef9ea75d5412737b5 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 14 Nov 2004 20:50:30 +0000 Subject: [PATCH] If a global is just loaded and restored, realize that it is not changing value. This allows us to turn more globals into constants and eliminate them. This patch implements GlobalOpt/load-store-global.llx. Note that this patch speeds up 255.vortex from: Output/255.vortex.out-cbe.time:program 7.640000 Output/255.vortex.out-llc.time:program 9.810000 to: Output/255.vortex.out-cbe.time:program 7.250000 Output/255.vortex.out-llc.time:program 9.490000 Which isn't bad at all! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17746 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/IPO/GlobalOpt.cpp | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index 054c5ee4306..b8edc32f16f 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -155,14 +155,20 @@ static bool AnalyzeGlobal(Value *V, GlobalStatus &GS, // stores. if (GS.StoredType != GlobalStatus::isStored) if (GlobalVariable *GV = dyn_cast(SI->getOperand(1))){ - if (SI->getOperand(0) == GV->getInitializer()) { + Value *StoredVal = SI->getOperand(0); + if (StoredVal == GV->getInitializer()) { + if (GS.StoredType < GlobalStatus::isInitializerStored) + GS.StoredType = GlobalStatus::isInitializerStored; + } else if (isa(StoredVal) && + cast(StoredVal)->getOperand(0) == GV) { + // G = G if (GS.StoredType < GlobalStatus::isInitializerStored) GS.StoredType = GlobalStatus::isInitializerStored; } else if (GS.StoredType < GlobalStatus::isStoredOnce) { GS.StoredType = GlobalStatus::isStoredOnce; - GS.StoredOnceValue = SI->getOperand(0); + GS.StoredOnceValue = StoredVal; } else if (GS.StoredType == GlobalStatus::isStoredOnce && - GS.StoredOnceValue == SI->getOperand(0)) { + GS.StoredOnceValue == StoredVal) { // noop. } else { GS.StoredType = GlobalStatus::isStored;