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-rw-r--r--contrib/llvm/lib/Transforms/Scalar/GlobalMerge.cpp137
1 files changed, 111 insertions, 26 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/GlobalMerge.cpp b/contrib/llvm/lib/Transforms/Scalar/GlobalMerge.cpp
index 6301aad..5d02c68 100644
--- a/contrib/llvm/lib/Transforms/Scalar/GlobalMerge.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/GlobalMerge.cpp
@@ -53,21 +53,28 @@
#define DEBUG_TYPE "global-merge"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Attributes.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Function.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
-#include "llvm/Module.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
-#include "llvm/DataLayout.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
-#include "llvm/ADT/Statistic.h"
using namespace llvm;
+static cl::opt<bool>
+EnableGlobalMergeOnConst("global-merge-on-const", cl::Hidden,
+ cl::desc("Enable global merge pass on constants"),
+ cl::init(false));
+
STATISTIC(NumMerged , "Number of globals merged");
namespace {
class GlobalMerge : public FunctionPass {
@@ -76,7 +83,24 @@ namespace {
const TargetLowering *TLI;
bool doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
- Module &M, bool isConst) const;
+ Module &M, bool isConst, unsigned AddrSpace) const;
+
+ /// \brief Check if the given variable has been identified as must keep
+ /// \pre setMustKeepGlobalVariables must have been called on the Module that
+ /// contains GV
+ bool isMustKeepGlobalVariable(const GlobalVariable *GV) const {
+ return MustKeepGlobalVariables.count(GV);
+ }
+
+ /// Collect every variables marked as "used" or used in a landing pad
+ /// instruction for this Module.
+ void setMustKeepGlobalVariables(Module &M);
+
+ /// Collect every variables marked as "used"
+ void collectUsedGlobalVariables(Module &M);
+
+ /// Keep track of the GlobalVariable that must not be merged away
+ SmallPtrSet<const GlobalVariable *, 16> MustKeepGlobalVariables;
public:
static char ID; // Pass identification, replacement for typeid.
@@ -87,6 +111,7 @@ namespace {
virtual bool doInitialization(Module &M);
virtual bool runOnFunction(Function &F);
+ virtual bool doFinalization(Module &M);
const char *getPassName() const {
return "Merge internal globals";
@@ -118,7 +143,7 @@ INITIALIZE_PASS(GlobalMerge, "global-merge",
bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
- Module &M, bool isConst) const {
+ Module &M, bool isConst, unsigned AddrSpace) const {
const DataLayout *TD = TLI->getDataLayout();
// FIXME: Infer the maximum possible offset depending on the actual users
@@ -150,7 +175,9 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
Constant *MergedInit = ConstantStruct::get(MergedTy, Inits);
GlobalVariable *MergedGV = new GlobalVariable(M, MergedTy, isConst,
GlobalValue::InternalLinkage,
- MergedInit, "_MergedGlobals");
+ MergedInit, "_MergedGlobals",
+ 0, GlobalVariable::NotThreadLocal,
+ AddrSpace);
for (size_t k = i; k < j; ++k) {
Constant *Idx[2] = {
ConstantInt::get(Int32Ty, 0),
@@ -167,12 +194,51 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
return true;
}
+void GlobalMerge::collectUsedGlobalVariables(Module &M) {
+ // Extract global variables from llvm.used array
+ const GlobalVariable *GV = M.getGlobalVariable("llvm.used");
+ if (!GV || !GV->hasInitializer()) return;
+
+ // Should be an array of 'i8*'.
+ const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
+ if (InitList == 0) return;
+
+ for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
+ if (const GlobalVariable *G =
+ dyn_cast<GlobalVariable>(InitList->getOperand(i)->stripPointerCasts()))
+ MustKeepGlobalVariables.insert(G);
+}
+
+void GlobalMerge::setMustKeepGlobalVariables(Module &M) {
+ collectUsedGlobalVariables(M);
+
+ for (Module::iterator IFn = M.begin(), IEndFn = M.end(); IFn != IEndFn;
+ ++IFn) {
+ for (Function::iterator IBB = IFn->begin(), IEndBB = IFn->end();
+ IBB != IEndBB; ++IBB) {
+ // Follow the inwoke link to find the landing pad instruction
+ const InvokeInst *II = dyn_cast<InvokeInst>(IBB->getTerminator());
+ if (!II) continue;
+
+ const LandingPadInst *LPInst = II->getUnwindDest()->getLandingPadInst();
+ // Look for globals in the clauses of the landing pad instruction
+ for (unsigned Idx = 0, NumClauses = LPInst->getNumClauses();
+ Idx != NumClauses; ++Idx)
+ if (const GlobalVariable *GV =
+ dyn_cast<GlobalVariable>(LPInst->getClause(Idx)
+ ->stripPointerCasts()))
+ MustKeepGlobalVariables.insert(GV);
+ }
+ }
+}
bool GlobalMerge::doInitialization(Module &M) {
- SmallVector<GlobalVariable*, 16> Globals, ConstGlobals, BSSGlobals;
+ DenseMap<unsigned, SmallVector<GlobalVariable*, 16> > Globals, ConstGlobals,
+ BSSGlobals;
const DataLayout *TD = TLI->getDataLayout();
unsigned MaxOffset = TLI->getMaximalGlobalOffset();
bool Changed = false;
+ setMustKeepGlobalVariables(M);
// Grab all non-const globals.
for (Module::global_iterator I = M.global_begin(),
@@ -181,6 +247,11 @@ bool GlobalMerge::doInitialization(Module &M) {
if (!I->hasLocalLinkage() || I->isThreadLocal() || I->hasSection())
continue;
+ PointerType *PT = dyn_cast<PointerType>(I->getType());
+ assert(PT && "Global variable is not a pointer!");
+
+ unsigned AddressSpace = PT->getAddressSpace();
+
// Ignore fancy-aligned globals for now.
unsigned Alignment = TD->getPreferredAlignment(I);
Type *Ty = I->getType()->getElementType();
@@ -192,27 +263,36 @@ bool GlobalMerge::doInitialization(Module &M) {
I->getName().startswith(".llvm."))
continue;
+ // Ignore all "required" globals:
+ if (isMustKeepGlobalVariable(I))
+ continue;
+
if (TD->getTypeAllocSize(Ty) < MaxOffset) {
if (TargetLoweringObjectFile::getKindForGlobal(I, TLI->getTargetMachine())
.isBSSLocal())
- BSSGlobals.push_back(I);
+ BSSGlobals[AddressSpace].push_back(I);
else if (I->isConstant())
- ConstGlobals.push_back(I);
+ ConstGlobals[AddressSpace].push_back(I);
else
- Globals.push_back(I);
+ Globals[AddressSpace].push_back(I);
}
}
- if (Globals.size() > 1)
- Changed |= doMerge(Globals, M, false);
- if (BSSGlobals.size() > 1)
- Changed |= doMerge(BSSGlobals, M, false);
+ for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
+ I = Globals.begin(), E = Globals.end(); I != E; ++I)
+ if (I->second.size() > 1)
+ Changed |= doMerge(I->second, M, false, I->first);
+
+ for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
+ I = BSSGlobals.begin(), E = BSSGlobals.end(); I != E; ++I)
+ if (I->second.size() > 1)
+ Changed |= doMerge(I->second, M, false, I->first);
- // FIXME: This currently breaks the EH processing due to way how the
- // typeinfo detection works. We might want to detect the TIs and ignore
- // them in the future.
- // if (ConstGlobals.size() > 1)
- // Changed |= doMerge(ConstGlobals, M, true);
+ if (EnableGlobalMergeOnConst)
+ for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
+ I = ConstGlobals.begin(), E = ConstGlobals.end(); I != E; ++I)
+ if (I->second.size() > 1)
+ Changed |= doMerge(I->second, M, true, I->first);
return Changed;
}
@@ -221,6 +301,11 @@ bool GlobalMerge::runOnFunction(Function &F) {
return false;
}
+bool GlobalMerge::doFinalization(Module &M) {
+ MustKeepGlobalVariables.clear();
+ return false;
+}
+
Pass *llvm::createGlobalMergePass(const TargetLowering *tli) {
return new GlobalMerge(tli);
}
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