[llvm-commits] [llvm] r85333 - in /llvm/trunk/lib/Target/ARM: ARMBaseRegisterInfo.cpp ARMBaseRegisterInfo.h
Jim Grosbach
grosbach at apple.com
Tue Oct 27 15:45:39 PDT 2009
Author: grosbach
Date: Tue Oct 27 17:45:39 2009
New Revision: 85333
URL: http://llvm.org/viewvc/llvm-project?rev=85333&view=rev
Log:
Infrastructure for dynamic stack realignment on ARM. For now, this is off by
default behind a command line option. This will enable better performance for
vectors on NEON enabled processors.
Modified:
llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h
Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp?rev=85333&r1=85332&r2=85333&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp Tue Oct 27 17:45:39 2009
@@ -29,6 +29,7 @@
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetFrameInfo.h"
@@ -48,6 +49,10 @@
ReuseFrameIndexVals("arm-reuse-frame-index-vals", cl::Hidden, cl::init(false),
cl::desc("Reuse repeated frame index values"));
+static cl::opt<bool>
+ARMDynamicStackAlign("arm-dynamic-stack-alignment", cl::Hidden, cl::init(false),
+ cl::desc("Dynamically re-align the stack as needed"));
+
unsigned ARMBaseRegisterInfo::getRegisterNumbering(unsigned RegEnum,
bool *isSPVFP) {
if (isSPVFP)
@@ -466,6 +471,21 @@
}
}
+static unsigned calculateMaxStackAlignment(const MachineFrameInfo *FFI) {
+ unsigned MaxAlign = 0;
+
+ for (int i = FFI->getObjectIndexBegin(),
+ e = FFI->getObjectIndexEnd(); i != e; ++i) {
+ if (FFI->isDeadObjectIndex(i))
+ continue;
+
+ unsigned Align = FFI->getObjectAlignment(i);
+ MaxAlign = std::max(MaxAlign, Align);
+ }
+
+ return MaxAlign;
+}
+
/// hasFP - Return true if the specified function should have a dedicated frame
/// pointer register. This is true if the function has variable sized allocas
/// or if frame pointer elimination is disabled.
@@ -473,10 +493,28 @@
bool ARMBaseRegisterInfo::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return (NoFramePointerElim ||
+ needsStackRealignment(MF) ||
MFI->hasVarSizedObjects() ||
MFI->isFrameAddressTaken());
}
+bool ARMBaseRegisterInfo::
+needsStackRealignment(const MachineFunction &MF) const {
+ // Only do this for ARM if explicitly enabled
+ // FIXME: Once it's passing all the tests, enable by default
+ if (!ARMDynamicStackAlign)
+ return false;
+
+ const MachineFrameInfo *MFI = MF.getFrameInfo();
+ const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ unsigned StackAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
+ return (RealignStack &&
+ !AFI->isThumb1OnlyFunction() &&
+ (MFI->getMaxAlignment() > StackAlign) &&
+ !MFI->hasVarSizedObjects());
+
+}
+
bool ARMBaseRegisterInfo::cannotEliminateFrame(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
if (NoFramePointerElim && MFI->hasCalls())
@@ -552,6 +590,16 @@
SmallVector<unsigned, 4> UnspilledCS2GPRs;
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ MachineFrameInfo *MFI = MF.getFrameInfo();
+
+ // Calculate and set max stack object alignment early, so we can decide
+ // whether we will need stack realignment (and thus FP).
+ if (ARMDynamicStackAlign) {
+ unsigned MaxAlign = std::max(MFI->getMaxAlignment(),
+ calculateMaxStackAlignment(MFI));
+ MFI->setMaxAlignment(MaxAlign);
+ }
+
// Don't spill FP if the frame can be eliminated. This is determined
// by scanning the callee-save registers to see if any is used.
const unsigned *CSRegs = getCalleeSavedRegs();
@@ -1085,16 +1133,28 @@
int FrameIndex = MI.getOperand(i).getIndex();
int Offset = MFI->getObjectOffset(FrameIndex) + MFI->getStackSize() + SPAdj;
+ // When doing dynamic stack realignment, all of these need to change(?)
if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea1Offset();
else if (AFI->isGPRCalleeSavedArea2Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea2Offset();
else if (AFI->isDPRCalleeSavedAreaFrame(FrameIndex))
Offset -= AFI->getDPRCalleeSavedAreaOffset();
- else if (hasFP(MF) && AFI->hasStackFrame()) {
+ else if (needsStackRealignment(MF)) {
+ // When dynamically realigning the stack, use the frame pointer for
+ // parameters, and the stack pointer for locals.
+ assert (hasFP(MF) && "dynamic stack realignment without a FP!");
+ if (FrameIndex < 0) {
+ FrameReg = getFrameRegister(MF);
+ Offset -= AFI->getFramePtrSpillOffset();
+ // When referencing from the frame pointer, stack pointer adjustments
+ // don't matter.
+ SPAdj = 0;
+ }
+ } else if (hasFP(MF) && AFI->hasStackFrame()) {
assert(SPAdj == 0 && "Unexpected stack offset!");
// Use frame pointer to reference fixed objects unless this is a
- // frameless function,
+ // frameless function.
FrameReg = getFrameRegister(MF);
Offset -= AFI->getFramePtrSpillOffset();
}
@@ -1303,6 +1363,18 @@
AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
+
+ // If we need dynamic stack realignment, do it here.
+ if (needsStackRealignment(MF)) {
+ unsigned Opc;
+ unsigned MaxAlign = MFI->getMaxAlignment();
+ assert (!AFI->isThumb1OnlyFunction());
+ Opc = AFI->isThumbFunction() ? ARM::t2BICri : ARM::BICri;
+
+ AddDefaultCC(AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(Opc), ARM::SP)
+ .addReg(ARM::SP, RegState::Kill)
+ .addImm(MaxAlign-1)));
+ }
}
static bool isCalleeSavedRegister(unsigned Reg, const unsigned *CSRegs) {
Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h?rev=85333&r1=85332&r2=85333&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h Tue Oct 27 17:45:39 2009
@@ -96,6 +96,8 @@
bool hasFP(const MachineFunction &MF) const;
+ bool needsStackRealignment(const MachineFunction &MF) const;
+
bool cannotEliminateFrame(const MachineFunction &MF) const;
void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
More information about the llvm-commits
mailing list