#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
+#include "llvm/Operator.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Analysis/DIBuilder.h"
return false;
}
+/// getPointeeAlignment - Compute the minimum alignment of the value pointed
+/// to by the given pointer.
+static unsigned getPointeeAlignment(Value *V, const TargetData &TD) {
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+ if (CE->getOpcode() == Instruction::BitCast ||
+ (CE->getOpcode() == Instruction::GetElementPtr &&
+ cast<GEPOperator>(CE)->hasAllZeroIndices()))
+ return getPointeeAlignment(CE->getOperand(0), TD);
+
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
+ if (!GV->isDeclaration())
+ return TD.getPreferredAlignment(GV);
+
+ if (PointerType *PT = dyn_cast<PointerType>(V->getType()))
+ return TD.getABITypeAlignment(PT->getElementType());
+
+ return 0;
+}
+
// performScalarRepl - This algorithm is a simple worklist driven algorithm,
// which runs on all of the alloca instructions in the function, removing them
continue;
// Check to see if this allocation is only modified by a memcpy/memmove from
- // a constant global. If this is the case, we can change all users to use
+ // a constant global whose alignment is equal to or exceeds that of the
+ // allocation. If this is the case, we can change all users to use
// the constant global instead. This is commonly produced by the CFE by
// constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
// is only subsequently read.
SmallVector<Instruction *, 4> ToDelete;
if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(AI, ToDelete)) {
- DEBUG(dbgs() << "Found alloca equal to global: " << *AI << '\n');
- DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
- for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
- ToDelete[i]->eraseFromParent();
- Constant *TheSrc = cast<Constant>(Copy->getSource());
- AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
- Copy->eraseFromParent(); // Don't mutate the global.
- AI->eraseFromParent();
- ++NumGlobals;
- Changed = true;
- continue;
+ if (AI->getAlignment() <= getPointeeAlignment(Copy->getSource(), *TD)) {
+ DEBUG(dbgs() << "Found alloca equal to global: " << *AI << '\n');
+ DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
+ for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
+ ToDelete[i]->eraseFromParent();
+ Constant *TheSrc = cast<Constant>(Copy->getSource());
+ AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
+ Copy->eraseFromParent(); // Don't mutate the global.
+ AI->eraseFromParent();
+ ++NumGlobals;
+ Changed = true;
+ continue;
+ }
}
// Check to see if we can perform the core SROA transformation. We cannot