//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "pei"
#include "PrologEpilogInserter.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
#include "llvm/ADT/IndexedMap.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/STLExtras.h"
#include <climits>
using namespace llvm;
+// FIXME: For testing purposes only. Remove once the pre-allocation pass
+// is done.
+extern cl::opt<bool> EnableLocalStackAlloc;
+
char PEI::ID = 0;
-static RegisterPass<PEI>
-X("prologepilog", "Prologue/Epilogue Insertion");
+INITIALIZE_PASS(PEI, "prologepilog",
+ "Prologue/Epilogue Insertion", false, false);
/// createPrologEpilogCodeInserter - This function returns a pass that inserts
/// prolog and epilog code, and eliminates abstract frame references.
calculateCalleeSavedRegisters(Fn);
// Determine placement of CSR spill/restore code:
- // - with shrink wrapping, place spills and restores to tightly
+ // - With shrink wrapping, place spills and restores to tightly
// enclose regions in the Machine CFG of the function where
- // they are used. Without shrink wrapping
- // - default (no shrink wrapping), place all spills in the
+ // they are used.
+ // - Without shink wrapping (default), place all spills in the
// entry block, all restores in return blocks.
placeCSRSpillsAndRestores(Fn);
Offset = (Offset + Align - 1) / Align * Align;
if (StackGrowsDown) {
+ DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << -Offset << "]\n");
MFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset
} else {
+ DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << Offset << "]\n");
MFI->setObjectOffset(FrameIdx, Offset);
Offset += MFI->getObjectSize(FrameIdx);
}
AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
}
+ // FIXME: Once this is working, then enable flag will change to a target
+ // check for whether the frame is large enough to want to use virtual
+ // frame index registers. Functions which don't want/need this optimization
+ // will continue to use the existing code path.
+ if (EnableLocalStackAlloc) {
+ unsigned Align = MFI->getLocalFrameMaxAlign();
+
+ // Adjust to alignment boundary.
+ Offset = (Offset + Align - 1) / Align * Align;
+
+ // Store the offset of the start of the local allocation block. This
+ // will be used later when resolving frame base virtual register pseudos.
+ MFI->setLocalFrameBaseOffset(Offset);
+
+ DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n");
+
+ // Allocate the local block
+ Offset += MFI->getLocalFrameSize();
+
+ // Resolve offsets for objects in the local block.
+ for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) {
+ std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i);
+ int64_t FIOffset = MFI->getLocalFrameBaseOffset() + Entry.second;
+
+ AdjustStackOffset(MFI, Entry.first, StackGrowsDown, FIOffset, MaxAlign);
+ }
+ }
+
// Make sure that the stack protector comes before the local variables on the
// stack.
- if (MFI->getStackProtectorIndex() >= 0)
+ SmallSet<int, 16> LargeStackObjs;
+ if (MFI->getStackProtectorIndex() >= 0) {
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), StackGrowsDown,
Offset, MaxAlign);
+ // Assign large stack objects first.
+ for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
+ if (MFI->isObjectPreAllocated(i))
+ continue;
+ if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
+ continue;
+ if (RS && (int)i == RS->getScavengingFrameIndex())
+ continue;
+ if (MFI->isDeadObjectIndex(i))
+ continue;
+ if (MFI->getStackProtectorIndex() == (int)i)
+ continue;
+ if (!MFI->MayNeedStackProtector(i))
+ continue;
+
+ AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign);
+ LargeStackObjs.insert(i);
+ }
+ }
+
// Then assign frame offsets to stack objects that are not used to spill
// callee saved registers.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
+ if (MFI->isObjectPreAllocated(i))
+ continue;
if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
continue;
if (RS && (int)i == RS->getScavengingFrameIndex())
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
+ if (LargeStackObjs.count(i))
+ continue;
AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign);
}
// Scavenge a new scratch register
CurrentVirtReg = Reg;
const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
- const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
- BitVector Candidates(TRI->getNumRegs());
- RS->getRegsAvailable(RC, Candidates);
-
- // If there are any registers available, use the one that's
- // unused for the longest after this instruction. That increases
- // the ability to reuse the value.
- if (Candidates.any()) {
- MachineBasicBlock::iterator UMI;
- CurrentScratchReg = RS->findSurvivorReg(I, Candidates, 25, UMI);
- } else {
- // No register is "free". Scavenge a register.
- CurrentScratchReg = RS->scavengeRegister(RC, I, SPAdj);
- }
-
+ CurrentScratchReg = RS->scavengeRegister(RC, I, SPAdj);
PrevValue = Value;
}
// replace this reference to the virtual register with the
projects / oota-llvm.git / blobdiff