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Better handling of local offsets for downwards growing stacks. This corrects

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relative offsets when there are offsets encoded in the instructions and
simplifies final allocation in PEI. rdar://8277890

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111836 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach
2010-08-23 20:40:38 +00:00
parent 11bc1652c9
commit 67ff81a083
2 changed files with 39 additions and 25 deletions
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50
lib/CodeGen/LocalStackSlotAllocation.cpp
View File

@@ -46,7 +46,7 @@ namespace {
SmallVector<int64_t,16> LocalOffsets; SmallVector<int64_t,16> LocalOffsets;
void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset, void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset,
unsigned &MaxAlign); bool StackGrowsDown, unsigned &MaxAlign);
void calculateFrameObjectOffsets(MachineFunction &Fn); void calculateFrameObjectOffsets(MachineFunction &Fn);
bool insertFrameReferenceRegisters(MachineFunction &Fn); bool insertFrameReferenceRegisters(MachineFunction &Fn);
public: public:
@@ -102,7 +102,12 @@ bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) {
/// AdjustStackOffset - Helper function used to adjust the stack frame offset. /// AdjustStackOffset - Helper function used to adjust the stack frame offset.
void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI, void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
int FrameIdx, int64_t &Offset, int FrameIdx, int64_t &Offset,
bool StackGrowsDown,
unsigned &MaxAlign) { unsigned &MaxAlign) {
// If the stack grows down, add the object size to find the lowest address.
if (StackGrowsDown)
Offset += MFI->getObjectSize(FrameIdx);
unsigned Align = MFI->getObjectAlignment(FrameIdx); unsigned Align = MFI->getObjectAlignment(FrameIdx);
// If the alignment of this object is greater than that of the stack, then // If the alignment of this object is greater than that of the stack, then
@@ -112,13 +117,16 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
// Adjust to alignment boundary. // Adjust to alignment boundary.
Offset = (Offset + Align - 1) / Align * Align; Offset = (Offset + Align - 1) / Align * Align;
int64_t LocalOffset = StackGrowsDown ? -Offset : Offset;
DEBUG(dbgs() << "Allocate FI(" << FrameIdx << ") to local offset " DEBUG(dbgs() << "Allocate FI(" << FrameIdx << ") to local offset "
<< Offset << "\n"); << LocalOffset << "\n");
// Keep the offset available for base register allocation // Keep the offset available for base register allocation
LocalOffsets[FrameIdx] = Offset; LocalOffsets[FrameIdx] = LocalOffset;
// And tell MFI about it for PEI to use later // And tell MFI about it for PEI to use later
MFI->mapLocalFrameObject(FrameIdx, Offset); MFI->mapLocalFrameObject(FrameIdx, LocalOffset);
Offset += MFI->getObjectSize(FrameIdx);
if (!StackGrowsDown)
Offset += MFI->getObjectSize(FrameIdx);
++NumAllocations; ++NumAllocations;
} }
@@ -129,6 +137,9 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
// Loop over all of the stack objects, assigning sequential addresses... // Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *MFI = Fn.getFrameInfo(); MachineFrameInfo *MFI = Fn.getFrameInfo();
const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
int64_t Offset = 0; int64_t Offset = 0;
unsigned MaxAlign = 0; unsigned MaxAlign = 0;
@@ -136,7 +147,8 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
// stack. // stack.
SmallSet<int, 16> LargeStackObjs; SmallSet<int, 16> LargeStackObjs;
if (MFI->getStackProtectorIndex() >= 0) { if (MFI->getStackProtectorIndex() >= 0) {
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset, MaxAlign); AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
StackGrowsDown, MaxAlign);
// Assign large stack objects first. // Assign large stack objects first.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
@@ -147,7 +159,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
if (!MFI->MayNeedStackProtector(i)) if (!MFI->MayNeedStackProtector(i))
continue; continue;
AdjustStackOffset(MFI, i, Offset, MaxAlign); AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
LargeStackObjs.insert(i); LargeStackObjs.insert(i);
} }
} }
@@ -162,7 +174,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
if (LargeStackObjs.count(i)) if (LargeStackObjs.count(i))
continue; continue;
AdjustStackOffset(MFI, i, Offset, MaxAlign); AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
} }
// Remember how big this blob of stack space is // Remember how big this blob of stack space is
@@ -173,8 +185,8 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
static inline bool static inline bool
lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs, lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
std::pair<unsigned, int64_t> &RegOffset, std::pair<unsigned, int64_t> &RegOffset,
int64_t FrameSizeAdjust,
int64_t LocalFrameOffset, int64_t LocalFrameOffset,
bool StackGrowsDown,
const MachineInstr *MI, const MachineInstr *MI,
const TargetRegisterInfo *TRI) { const TargetRegisterInfo *TRI) {
unsigned e = Regs.size(); unsigned e = Regs.size();
@@ -182,9 +194,7 @@ lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
RegOffset = Regs[i]; RegOffset = Regs[i];
// Check if the relative offset from the where the base register references // Check if the relative offset from the where the base register references
// to the target address is in range for the instruction. // to the target address is in range for the instruction.
int64_t Offset = LocalFrameOffset - RegOffset.second; int64_t Offset = FrameSizeAdjust + LocalFrameOffset - RegOffset.second;
if (StackGrowsDown)
Offset = -Offset;
if (TRI->isFrameOffsetLegal(MI, Offset)) if (TRI->isFrameOffsetLegal(MI, Offset))
return true; return true;
} }
@@ -241,6 +251,8 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
if (TRI->needsFrameBaseReg(MI, i)) { if (TRI->needsFrameBaseReg(MI, i)) {
unsigned BaseReg = 0; unsigned BaseReg = 0;
int64_t Offset = 0; int64_t Offset = 0;
int64_t FrameSizeAdjust = StackGrowsDown ? MFI->getLocalFrameSize()
: 0;
DEBUG(dbgs() << " Replacing FI in: " << *MI); DEBUG(dbgs() << " Replacing FI in: " << *MI);
@@ -251,15 +263,15 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// register. // register.
std::pair<unsigned, int64_t> RegOffset; std::pair<unsigned, int64_t> RegOffset;
if (lookupCandidateBaseReg(BaseRegisters, RegOffset, if (lookupCandidateBaseReg(BaseRegisters, RegOffset,
FrameSizeAdjust,
LocalOffsets[FrameIdx], LocalOffsets[FrameIdx],
StackGrowsDown, MI, TRI)) { MI, TRI)) {
DEBUG(dbgs() << " Reusing base register " << DEBUG(dbgs() << " Reusing base register " <<
RegOffset.first << "\n"); RegOffset.first << "\n");
// We found a register to reuse. // We found a register to reuse.
BaseReg = RegOffset.first; BaseReg = RegOffset.first;
Offset = LocalOffsets[FrameIdx] - RegOffset.second; Offset = FrameSizeAdjust + LocalOffsets[FrameIdx] -
if (StackGrowsDown) RegOffset.second;
Offset = -Offset;
} else { } else {
// No previously defined register was in range, so create a // No previously defined register was in range, so create a
// new one. // new one.
@@ -280,9 +292,10 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// applied twice. // applied twice.
Offset = -InstrOffset; Offset = -InstrOffset;
int64_t BaseOffset = FrameSizeAdjust + LocalOffsets[FrameIdx] +
InstrOffset;
BaseRegisters.push_back( BaseRegisters.push_back(
std::pair<unsigned, int64_t>(BaseReg, std::pair<unsigned, int64_t>(BaseReg, BaseOffset));
LocalOffsets[FrameIdx] + InstrOffset));
++NumBaseRegisters; ++NumBaseRegisters;
UsedBaseReg = true; UsedBaseReg = true;
} }
@@ -295,7 +308,6 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
++NumReplacements; ++NumReplacements;
} }
} }
} }
} }

14
lib/CodeGen/PrologEpilogInserter.cpp
View File

@@ -572,16 +572,18 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n"); DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n");
// Allocate the local block
Offset += MFI->getLocalFrameSize();
// Resolve offsets for objects in the local block. // Resolve offsets for objects in the local block.
for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) { for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) {
std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i); std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i);
int64_t FIOffset = MFI->getLocalFrameBaseOffset() + Entry.second; int64_t FIOffset = (StackGrowsDown ? -Offset : Offset) + Entry.second;
DEBUG(dbgs() << "alloc FI(" << Entry.first << ") at SP[" <<
AdjustStackOffset(MFI, Entry.first, StackGrowsDown, FIOffset, MaxAlign); FIOffset << "]\n");
MFI->setObjectOffset(Entry.first, FIOffset);
} }
// Allocate the local block
Offset += MFI->getLocalFrameSize();
MaxAlign = std::max(Align, MaxAlign);
} }
// Make sure that the stack protector comes before the local variables on the // Make sure that the stack protector comes before the local variables on the