#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/MathExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
};
-
- char GlobalOpt::ID = 0;
- RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
}
+char GlobalOpt::ID = 0;
+static RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
+
ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
+namespace {
+
/// GlobalStatus - As we analyze each global, keep track of some information
/// about it. If we find out that the address of the global is taken, none of
/// this info will be accurate.
HasNonInstructionUser(false), HasPHIUser(false) {}
};
-
+}
/// ConstantIsDead - Return true if the specified constant is (transitively)
/// dead. The constant may be used by other constants (e.g. constant arrays and
/// behavior of the program in a more fine-grained way. We have determined that
/// this transformation is safe already. We return the first global variable we
/// insert so that the caller can reprocess it.
-static GlobalVariable *SRAGlobal(GlobalVariable *GV) {
+static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) {
// Make sure this global only has simple uses that we can SRA.
if (!GlobalUsersSafeToSRA(GV))
return 0;
std::vector<GlobalVariable*> NewGlobals;
Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
+ // Get the alignment of the global, either explicit or target-specific.
+ unsigned StartAlignment = GV->getAlignment();
+ if (StartAlignment == 0)
+ StartAlignment = TD.getABITypeAlignment(GV->getType());
+
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
NewGlobals.reserve(STy->getNumElements());
+ const StructLayout &Layout = *TD.getStructLayout(STy);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Constant *In = getAggregateConstantElement(Init,
ConstantInt::get(Type::Int32Ty, i));
GV->isThreadLocal());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
+
+ // Calculate the known alignment of the field. If the original aggregate
+ // had 256 byte alignment for example, something might depend on that:
+ // propagate info to each field.
+ uint64_t FieldOffset = Layout.getElementOffset(i);
+ unsigned NewAlign = (unsigned)MinAlign(StartAlignment, FieldOffset);
+ if (NewAlign > TD.getABITypeAlignment(STy->getElementType(i)))
+ NGV->setAlignment(NewAlign);
}
} else if (const SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
unsigned NumElements = 0;
if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
NumElements = ATy->getNumElements();
- else if (const VectorType *PTy = dyn_cast<VectorType>(STy))
- NumElements = PTy->getNumElements();
else
- assert(0 && "Unknown aggregate sequential type!");
+ NumElements = cast<VectorType>(STy)->getNumElements();
if (NumElements > 16 && GV->hasNUsesOrMore(16))
return 0; // It's not worth it.
NewGlobals.reserve(NumElements);
+
+ uint64_t EltSize = TD.getABITypeSize(STy->getElementType());
+ unsigned EltAlign = TD.getABITypeAlignment(STy->getElementType());
for (unsigned i = 0, e = NumElements; i != e; ++i) {
Constant *In = getAggregateConstantElement(Init,
ConstantInt::get(Type::Int32Ty, i));
GV->isThreadLocal());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
+
+ // Calculate the known alignment of the field. If the original aggregate
+ // had 256 byte alignment for example, something might depend on that:
+ // propagate info to each field.
+ unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i);
+ if (NewAlign > EltAlign)
+ NGV->setAlignment(NewAlign);
}
}
GV->getName()+".body",
(Module *)NULL,
GV->isThreadLocal());
+ // FIXME: This new global should have the alignment returned by malloc. Code
+ // could depend on malloc returning large alignment (on the mac, 16 bytes) but
+ // this would only guarantee some lower alignment.
GV->getParent()->getGlobalList().insert(GV, NewGV);
// Anything that used the malloc now uses the global directly.
++NumMarked;
return true;
} else if (!GV->getInitializer()->getType()->isFirstClassType()) {
- if (GlobalVariable *FirstNewGV = SRAGlobal(GV)) {
+ if (GlobalVariable *FirstNewGV = SRAGlobal(GV,
+ getAnalysis<TargetData>())) {
GVI = FirstNewGV; // Don't skip the newly produced globals!
return true;
}