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Refactor InferAlignment out of DAGCombine. 

llvm-svn: 90917
This commit is contained in:
Evan Cheng 2009-12-09 01:04:59 +00:00
parent 11da6b0050
commit 34a23ea371
3 changed files with 50 additions and 45 deletions
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4
llvm/include/llvm/CodeGen/SelectionDAG.h
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@ -890,6 +890,10 @@ public:
/// vector op and fill the end of the resulting vector with UNDEFS.
SDValue UnrollVectorOp(SDNode *N, unsigned ResNE = 0);
/// InferPtrAlignment - Infer alignment of a load / store address. Return 0 if
/// it cannot be inferred.
unsigned InferPtrAlignment(SDValue Ptr);
private:
bool RemoveNodeFromCSEMaps(SDNode *N);
void AddModifiedNodeToCSEMaps(SDNode *N, DAGUpdateListener *UpdateListener);

47
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -4811,49 +4811,6 @@ bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
return false;
}
/// InferAlignment - If we can infer some alignment information from this
/// pointer, return it.
static unsigned InferAlignment(SDValue Ptr, SelectionDAG &DAG) {
// If this is a direct reference to a stack slot, use information about the
// stack slot's alignment.
int FrameIdx = 1 << 31;
int64_t FrameOffset = 0;
if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Ptr)) {
FrameIdx = FI->getIndex();
} else if (Ptr.getOpcode() == ISD::ADD &&
isa<ConstantSDNode>(Ptr.getOperand(1)) &&
isa<FrameIndexSDNode>(Ptr.getOperand(0))) {
FrameIdx = cast<FrameIndexSDNode>(Ptr.getOperand(0))->getIndex();
FrameOffset = Ptr.getConstantOperandVal(1);
}
if (FrameIdx != (1 << 31)) {
// FIXME: Handle FI+CST.
const MachineFrameInfo &MFI = *DAG.getMachineFunction().getFrameInfo();
if (MFI.isFixedObjectIndex(FrameIdx)) {
int64_t ObjectOffset = MFI.getObjectOffset(FrameIdx) + FrameOffset;
// The alignment of the frame index can be determined from its offset from
// the incoming frame position. If the frame object is at offset 32 and
// the stack is guaranteed to be 16-byte aligned, then we know that the
// object is 16-byte aligned.
unsigned StackAlign = DAG.getTarget().getFrameInfo()->getStackAlignment();
unsigned Align = MinAlign(ObjectOffset, StackAlign);
// Finally, the frame object itself may have a known alignment. Factor
// the alignment + offset into a new alignment. For example, if we know
// the FI is 8 byte aligned, but the pointer is 4 off, we really have a
// 4-byte alignment of the resultant pointer. Likewise align 4 + 4-byte
// offset = 4-byte alignment, align 4 + 1-byte offset = align 1, etc.
unsigned FIInfoAlign = MinAlign(MFI.getObjectAlignment(FrameIdx),
FrameOffset);
return std::max(Align, FIInfoAlign);
}
}
return 0;
}
SDValue DAGCombiner::visitLOAD(SDNode *N) {
LoadSDNode *LD = cast<LoadSDNode>(N);
SDValue Chain = LD->getChain();
@ -4861,7 +4818,7 @@ SDValue DAGCombiner::visitLOAD(SDNode *N) {
// Try to infer better alignment information than the load already has.
if (OptLevel != CodeGenOpt::None && LD->isUnindexed()) {
if (unsigned Align = InferAlignment(Ptr, DAG)) {
if (unsigned Align = DAG.InferPtrAlignment(Ptr)) {
if (Align > LD->getAlignment())
return DAG.getExtLoad(LD->getExtensionType(), N->getDebugLoc(),
LD->getValueType(0),
@ -5086,7 +5043,7 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
// Try to infer better alignment information than the store already has.
if (OptLevel != CodeGenOpt::None && ST->isUnindexed()) {
if (unsigned Align = InferAlignment(Ptr, DAG)) {
if (unsigned Align = DAG.InferPtrAlignment(Ptr)) {
if (Align > ST->getAlignment())
return DAG.getTruncStore(Chain, N->getDebugLoc(), Value,
Ptr, ST->getSrcValue(),

44
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -27,6 +27,7 @@
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetInstrInfo.h"
@ -5867,6 +5868,49 @@ SDValue SelectionDAG::UnrollVectorOp(SDNode *N, unsigned ResNE) {
&Scalars[0], Scalars.size());
}
/// InferPtrAlignment - Infer alignment of a load / store address. Return 0 if
/// it cannot be inferred.
unsigned SelectionDAG::InferPtrAlignment(SDValue Ptr) {
// If this is a direct reference to a stack slot, use information about the
// stack slot's alignment.
int FrameIdx = 1 << 31;
int64_t FrameOffset = 0;
if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Ptr)) {
FrameIdx = FI->getIndex();
} else if (Ptr.getOpcode() == ISD::ADD &&
isa<ConstantSDNode>(Ptr.getOperand(1)) &&
isa<FrameIndexSDNode>(Ptr.getOperand(0))) {
FrameIdx = cast<FrameIndexSDNode>(Ptr.getOperand(0))->getIndex();
FrameOffset = Ptr.getConstantOperandVal(1);
}
if (FrameIdx != (1 << 31)) {
// FIXME: Handle FI+CST.
const MachineFrameInfo &MFI = *getMachineFunction().getFrameInfo();
if (MFI.isFixedObjectIndex(FrameIdx)) {
int64_t ObjectOffset = MFI.getObjectOffset(FrameIdx) + FrameOffset;
// The alignment of the frame index can be determined from its offset from
// the incoming frame position. If the frame object is at offset 32 and
// the stack is guaranteed to be 16-byte aligned, then we know that the
// object is 16-byte aligned.
unsigned StackAlign = getTarget().getFrameInfo()->getStackAlignment();
unsigned Align = MinAlign(ObjectOffset, StackAlign);
// Finally, the frame object itself may have a known alignment. Factor
// the alignment + offset into a new alignment. For example, if we know
// the FI is 8 byte aligned, but the pointer is 4 off, we really have a
// 4-byte alignment of the resultant pointer. Likewise align 4 + 4-byte
// offset = 4-byte alignment, align 4 + 1-byte offset = align 1, etc.
unsigned FIInfoAlign = MinAlign(MFI.getObjectAlignment(FrameIdx),
FrameOffset);
return std::max(Align, FIInfoAlign);
}
}
return 0;
}
void SelectionDAG::dump() const {
errs() << "SelectionDAG has " << AllNodes.size() << " nodes:";