From 6ffce6fa9295699078f81fabb9ca32f6f22bdf09 Mon Sep 17 00:00:00 2001 From: Alexey Samsonov Date: Wed, 2 Oct 2013 15:31:34 +0000 Subject: [PATCH] Remove "localize global" optimization Summary: As discussed in http://llvm-reviews.chandlerc.com/D1754, this optimization isn't really valid for C, and fires too rarely anyway. Reviewers: rafael, nicholas Reviewed By: nicholas CC: rnk, llvm-commits, nicholas Differential Revision: http://llvm-reviews.chandlerc.com/D1769 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191834 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/IPO/GlobalOpt.cpp | 59 ++------------------------- test/Transforms/GlobalOpt/metadata.ll | 26 ------------ 2 files changed, 3 insertions(+), 82 deletions(-) delete mode 100644 test/Transforms/GlobalOpt/metadata.ll diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index cf15580b039..3129559fb99 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -50,7 +50,6 @@ STATISTIC(NumSubstitute,"Number of globals with initializers stored into them"); STATISTIC(NumDeleted , "Number of globals deleted"); STATISTIC(NumFnDeleted , "Number of functions deleted"); STATISTIC(NumGlobUses , "Number of global uses devirtualized"); -STATISTIC(NumLocalized , "Number of globals localized"); STATISTIC(NumShrunkToBool , "Number of global vars shrunk to booleans"); STATISTIC(NumFastCallFns , "Number of functions converted to fastcc"); STATISTIC(NumCtorsEvaluated, "Number of static ctors evaluated"); @@ -137,24 +136,12 @@ struct GlobalStatus { /// ever stored to this global, keep track of what value it is. Value *StoredOnceValue; - /// AccessingFunction/HasMultipleAccessingFunctions - These start out - /// null/false. When the first accessing function is noticed, it is recorded. - /// When a second different accessing function is noticed, - /// HasMultipleAccessingFunctions is set to true. - const Function *AccessingFunction; - bool HasMultipleAccessingFunctions; - - /// HasNonInstructionUser - Set to true if this global has a user that is not - /// an instruction (e.g. a constant expr or GV initializer). - bool HasNonInstructionUser; - /// AtomicOrdering - Set to the strongest atomic ordering requirement. AtomicOrdering Ordering; - GlobalStatus() : isCompared(false), isLoaded(false), StoredType(NotStored), - StoredOnceValue(0), AccessingFunction(0), - HasMultipleAccessingFunctions(false), - HasNonInstructionUser(false), Ordering(NotAtomic) {} + GlobalStatus() + : isCompared(false), isLoaded(false), StoredType(NotStored), + StoredOnceValue(0), Ordering(NotAtomic) {} }; } @@ -195,21 +182,12 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS, ++UI) { const User *U = *UI; if (const ConstantExpr *CE = dyn_cast(U)) { - GS.HasNonInstructionUser = true; - // If the result of the constantexpr isn't pointer type, then we won't // know to expect it in various places. Just reject early. if (!isa(CE->getType())) return true; if (AnalyzeGlobal(CE, GS, PHIUsers)) return true; } else if (const Instruction *I = dyn_cast(U)) { - if (!GS.HasMultipleAccessingFunctions) { - const Function *F = I->getParent()->getParent(); - if (GS.AccessingFunction == 0) - GS.AccessingFunction = F; - else if (GS.AccessingFunction != F) - GS.HasMultipleAccessingFunctions = true; - } if (const LoadInst *LI = dyn_cast(I)) { GS.isLoaded = true; // Don't hack on volatile loads. @@ -286,12 +264,10 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS, return true; // Any other non-load instruction might take address! } } else if (const Constant *C = dyn_cast(U)) { - GS.HasNonInstructionUser = true; // We might have a dead and dangling constant hanging off of here. if (!SafeToDestroyConstant(C)) return true; } else { - GS.HasNonInstructionUser = true; // Otherwise must be some other user. return true; } @@ -1938,35 +1914,6 @@ bool GlobalOpt::ProcessGlobal(GlobalVariable *GV, bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV, Module::global_iterator &GVI, const GlobalStatus &GS) { - // If this is a first class global and has only one accessing function - // and this function is main (which we know is not recursive), we replace - // the global with a local alloca in this function. - // - // NOTE: It doesn't make sense to promote non single-value types since we - // are just replacing static memory to stack memory. - // - // If the global is in different address space, don't bring it to stack. - if (!GS.HasMultipleAccessingFunctions && - GS.AccessingFunction && !GS.HasNonInstructionUser && - GV->getType()->getElementType()->isSingleValueType() && - GS.AccessingFunction->getName() == "main" && - GS.AccessingFunction->hasExternalLinkage() && - GV->getType()->getAddressSpace() == 0) { - DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV); - Instruction &FirstI = const_cast(*GS.AccessingFunction - ->getEntryBlock().begin()); - Type *ElemTy = GV->getType()->getElementType(); - // FIXME: Pass Global's alignment when globals have alignment - AllocaInst *Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI); - if (!isa(GV->getInitializer())) - new StoreInst(GV->getInitializer(), Alloca, &FirstI); - - GV->replaceAllUsesWith(Alloca); - GV->eraseFromParent(); - ++NumLocalized; - return true; - } - // If the global is never loaded (but may be stored to), it is dead. // Delete it now. if (!GS.isLoaded) { diff --git a/test/Transforms/GlobalOpt/metadata.ll b/test/Transforms/GlobalOpt/metadata.ll deleted file mode 100644 index ecf3f94196b..00000000000 --- a/test/Transforms/GlobalOpt/metadata.ll +++ /dev/null @@ -1,26 +0,0 @@ -; RUN: opt -S -globalopt < %s | FileCheck %s - -; PR6112 - When globalopt does RAUW(@G, %G), the metadata reference should drop -; to null. Function local metadata that references @G from a different function -; to that containing %G should likewise drop to null. -@G = internal global i8** null - -define i32 @main(i32 %argc, i8** %argv) { -; CHECK-LABEL: @main( -; CHECK: %G = alloca - store i8** %argv, i8*** @G - ret i32 0 -} - -define void @foo(i32 %x) { - call void @llvm.foo(metadata !{i8*** @G, i32 %x}) -; CHECK: call void @llvm.foo(metadata !{null, i32 %x}) - ret void -} - -declare void @llvm.foo(metadata) nounwind readnone - -!named = !{!0} - -!0 = metadata !{i8*** @G} -; CHECK: !0 = metadata !{null} -- 2.34.1