Hoist the GEP constant address offset computation to a common home on
the GEP instruction class.
This is part of the continued refactoring and cleaning of the
infrastructure used by SROA. This particular operation is also done in
a few other places which I'll try to refactor to share this
implementation.
llvm-svn: 169852
diff --git a/llvm/lib/VMCore/Instructions.cpp b/llvm/lib/VMCore/Instructions.cpp
index ded9534..3bc4bfe 100644
--- a/llvm/lib/VMCore/Instructions.cpp
+++ b/llvm/lib/VMCore/Instructions.cpp
@@ -15,6 +15,7 @@
#include "llvm/Instructions.h"
#include "LLVMContextImpl.h"
#include "llvm/Constants.h"
+#include "llvm/DataLayout.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Module.h"
@@ -22,6 +23,7 @@
#include "llvm/Support/CallSite.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
@@ -1423,6 +1425,37 @@
return cast<GEPOperator>(this)->isInBounds();
}
+bool GetElementPtrInst::accumulateConstantOffset(const DataLayout &DL,
+ APInt &Offset) const {
+ assert(Offset.getBitWidth() ==
+ DL.getPointerSizeInBits(getPointerAddressSpace()) &&
+ "The offset must have exactly as many bits as our pointer.");
+
+ for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
+ GTI != GTE; ++GTI) {
+ ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
+ if (!OpC)
+ return false;
+ if (OpC->isZero())
+ continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
+ unsigned ElementIdx = OpC->getZExtValue();
+ const StructLayout *SL = DL.getStructLayout(STy);
+ Offset += APInt(Offset.getBitWidth(),
+ SL->getElementOffset(ElementIdx));
+ continue;
+ }
+
+ // For array or vector indices, scale the index by the size of the type.
+ APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
+ Offset += Index * APInt(Offset.getBitWidth(),
+ DL.getTypeAllocSize(GTI.getIndexedType()));
+ }
+ return true;
+}
+
//===----------------------------------------------------------------------===//
// ExtractElementInst Implementation
//===----------------------------------------------------------------------===//