[llvm-commits] [llvm] r79139 - /llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp
Bill Wendling
isanbard at gmail.com
Sat Aug 15 14:27:32 PDT 2009
Author: void
Date: Sat Aug 15 16:27:32 2009
New Revision: 79139
URL: http://llvm.org/viewvc/llvm-project?rev=79139&view=rev
Log:
An overhaul of the exception handling code. This is arguably more correct than
what was there before. In "no FP mode", we weren't generating labels and unwind
table entries after each "push" instruction. While more than likely "okay", it's
not technically correct. The major thing was that the ordering of when to define
a new CFA register and at what offset wasn't correct. This would cause the
exception handling to fail in ways most miserable to users.
I also cleaned up some code a bit. There's one function which has a "return" at
the beginning, so it's never used. Should I just remove it? :-)
Modified:
llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp
Modified: llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp?rev=79139&r1=79138&r2=79139&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp Sat Aug 15 16:27:32 2009
@@ -677,9 +677,9 @@
uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
MachineInstr *MI =
BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
- .addReg(StackPtr).addImm(ThisVal);
- // The EFLAGS implicit def is dead.
- MI->getOperand(3).setIsDead();
+ .addReg(StackPtr)
+ .addImm(ThisVal);
+ MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
Offset -= ThisVal;
}
}
@@ -712,6 +712,7 @@
void mergeSPUpdatesDown(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned StackPtr, uint64_t *NumBytes = NULL) {
+ // FIXME: THIS ISN'T RUN!!!
return;
if (MBBI == MBB.end()) return;
@@ -840,50 +841,47 @@
}
}
+/// emitPrologue - Push callee-saved registers onto the stack, which
+/// automatically adjust the stack pointer. Adjust the stack pointer to allocate
+/// space for local variables. Also emit labels used by the exception handler to
+/// generate the exception handling frames.
void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
- MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
+ MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB.
+ MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
- const Function* Fn = MF.getFunction();
- const X86Subtarget* Subtarget = &MF.getTarget().getSubtarget<X86Subtarget>();
+ const Function *Fn = MF.getFunction();
+ const X86Subtarget *Subtarget = &MF.getTarget().getSubtarget<X86Subtarget>();
MachineModuleInfo *MMI = MFI->getMachineModuleInfo();
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
- MachineBasicBlock::iterator MBBI = MBB.begin();
bool needsFrameMoves = (MMI && MMI->hasDebugInfo()) ||
- !Fn->doesNotThrow() ||
- UnwindTablesMandatory;
+ !Fn->doesNotThrow() || UnwindTablesMandatory;
+ uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment.
+ uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate.
bool HasFP = hasFP(MF);
DebugLoc DL;
- // Get the number of bytes to allocate from the FrameInfo.
- uint64_t StackSize = MFI->getStackSize();
-
- // Get desired stack alignment
- uint64_t MaxAlign = MFI->getMaxAlignment();
-
// Add RETADDR move area to callee saved frame size.
int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
if (TailCallReturnAddrDelta < 0)
X86FI->setCalleeSavedFrameSize(
- X86FI->getCalleeSavedFrameSize() +(-TailCallReturnAddrDelta));
+ X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta);
// If this is x86-64 and the Red Zone is not disabled, if we are a leaf
// function, and use up to 128 bytes of stack space, don't have a frame
// pointer, calls, or dynamic alloca then we do not need to adjust the
// stack pointer (we fit in the Red Zone).
- bool DisableRedZone = Fn->hasFnAttr(Attribute::NoRedZone);
- if (Is64Bit && !DisableRedZone &&
+ if (Is64Bit && !Fn->hasFnAttr(Attribute::NoRedZone) &&
!needsStackRealignment(MF) &&
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->hasCalls() && // No calls.
!Subtarget->isTargetWin64()) { // Win64 has no Red Zone
uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
if (HasFP) MinSize += SlotSize;
- StackSize = std::max(MinSize,
- StackSize > 128 ? StackSize - 128 : 0);
+ StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0);
MFI->setStackSize(StackSize);
} else if (Subtarget->isTargetWin64()) {
// We need to always allocate 32 bytes as register spill area.
- // FIXME: we might reuse these 32 bytes for leaf functions.
+ // FIXME: We might reuse these 32 bytes for leaf functions.
StackSize += 32;
MFI->setStackSize(StackSize);
}
@@ -894,25 +892,39 @@
if (TailCallReturnAddrDelta < 0) {
MachineInstr *MI =
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit? X86::SUB64ri32 : X86::SUB32ri),
- StackPtr).addReg(StackPtr).addImm(-TailCallReturnAddrDelta);
- // The EFLAGS implicit def is dead.
- MI->getOperand(3).setIsDead();
- }
+ StackPtr)
+ .addReg(StackPtr)
+ .addImm(-TailCallReturnAddrDelta);
+ MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
+ }
+
+ // Mapping for machine moves:
+ //
+ // DST: VirtualFP AND
+ // SRC: VirtualFP => DW_CFA_def_cfa_offset
+ // ELSE => DW_CFA_def_cfa
+ //
+ // SRC: VirtualFP AND
+ // DST: Register => DW_CFA_def_cfa_register
+ //
+ // ELSE
+ // OFFSET < 0 => DW_CFA_offset_extended_sf
+ // REG < 64 => DW_CFA_offset + Reg
+ // ELSE => DW_CFA_offset_extended
- // uint64_t StackSize = MFI->getStackSize();
std::vector<MachineMove> &Moves = MMI->getFrameMoves();
const TargetData *TD = MF.getTarget().getTargetData();
+ uint64_t NumBytes = 0;
int stackGrowth =
(MF.getTarget().getFrameInfo()->getStackGrowthDirection() ==
TargetFrameInfo::StackGrowsUp ?
- TD->getPointerSize() : -TD->getPointerSize());
+ TD->getPointerSize() : -TD->getPointerSize());
- uint64_t NumBytes = 0;
if (HasFP) {
- // Calculate required stack adjustment
+ // Calculate required stack adjustment.
uint64_t FrameSize = StackSize - SlotSize;
if (needsStackRealignment(MF))
- FrameSize = (FrameSize + MaxAlign - 1)/MaxAlign*MaxAlign;
+ FrameSize = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign;
NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize();
@@ -921,12 +933,12 @@
// Update the frame offset adjustment.
MFI->setOffsetAdjustment(-NumBytes);
- // Save EBP/RBP into the appropriate stack slot...
+ // Save EBP/RBP into the appropriate stack slot.
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r))
.addReg(FramePtr, RegState::Kill);
if (needsFrameMoves) {
- // Mark effective beginning of when frame pointer becomes valid.
+ // Mark the place where EBP/RBP was saved.
unsigned FrameLabelId = MMI->NextLabelID();
BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(FrameLabelId);
@@ -934,8 +946,7 @@
if (StackSize) {
MachineLocation SPDst(MachineLocation::VirtualFP);
MachineLocation SPSrc(MachineLocation::VirtualFP,
- HasFP ? 2 * stackGrowth :
- -StackSize + stackGrowth);
+ 2 * stackGrowth);
Moves.push_back(MachineMove(FrameLabelId, SPDst, SPSrc));
} else {
// FIXME: Verify & implement for FP
@@ -945,7 +956,8 @@
}
// Change the rule for the FramePtr to be an "offset" rule.
- MachineLocation FPDst(MachineLocation::VirtualFP, 2 * stackGrowth);
+ MachineLocation FPDst(MachineLocation::VirtualFP,
+ 2 * stackGrowth);
MachineLocation FPSrc(FramePtr);
Moves.push_back(MachineMove(FrameLabelId, FPDst, FPSrc));
}
@@ -956,6 +968,7 @@
.addReg(StackPtr);
if (needsFrameMoves) {
+ // Mark effective beginning of when frame pointer becomes valid.
unsigned FrameLabelId = MMI->NextLabelID();
BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(FrameLabelId);
@@ -985,21 +998,28 @@
}
// Skip the callee-saved push instructions.
- bool RegsSaved = false;
+ bool PushedRegs = false;
+ int StackOffset = 2 * stackGrowth;
+
while (MBBI != MBB.end() &&
(MBBI->getOpcode() == X86::PUSH32r ||
MBBI->getOpcode() == X86::PUSH64r)) {
- RegsSaved = true;
+ PushedRegs = true;
++MBBI;
- }
- if (RegsSaved && needsFrameMoves) {
- // Mark end of callee-saved push instructions.
- unsigned LabelId = MMI->NextLabelID();
- BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(LabelId);
+ if (!HasFP && needsFrameMoves) {
+ // Mark callee-saved push instruction.
+ unsigned LabelId = MMI->NextLabelID();
+ BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(LabelId);
- // Emit DWARF info specifying the offsets of the callee-saved registers.
- emitCalleeSavedFrameMoves(MF, LabelId, HasFP ? FramePtr : StackPtr);
+ // Define the current CFA rule to use the provided offset.
+ unsigned Ptr = StackSize ?
+ MachineLocation::VirtualFP : StackPtr;
+ MachineLocation SPDst(Ptr);
+ MachineLocation SPSrc(Ptr, StackOffset);
+ Moves.push_back(MachineMove(LabelId, SPDst, SPSrc));
+ StackOffset += stackGrowth;
+ }
}
if (MBBI != MBB.end())
@@ -1058,23 +1078,29 @@
emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII);
}
- if (!HasFP && needsFrameMoves) {
+ if (NumBytes && needsFrameMoves) {
// Mark end of stack pointer adjustment.
unsigned LabelId = MMI->NextLabelID();
BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(LabelId);
- // Define the current CFA rule to use the provided offset.
- if (StackSize) {
- MachineLocation SPDst(MachineLocation::VirtualFP);
- MachineLocation SPSrc(MachineLocation::VirtualFP,
- -StackSize + stackGrowth);
- Moves.push_back(MachineMove(LabelId, SPDst, SPSrc));
- } else {
- // FIXME: Verify & implement for FP
- MachineLocation SPDst(StackPtr);
- MachineLocation SPSrc(StackPtr, stackGrowth);
- Moves.push_back(MachineMove(LabelId, SPDst, SPSrc));
+ if (!HasFP) {
+ // Define the current CFA rule to use the provided offset.
+ if (StackSize) {
+ MachineLocation SPDst(MachineLocation::VirtualFP);
+ MachineLocation SPSrc(MachineLocation::VirtualFP,
+ -StackSize + stackGrowth);
+ Moves.push_back(MachineMove(LabelId, SPDst, SPSrc));
+ } else {
+ // FIXME: Verify & implement for FP
+ MachineLocation SPDst(StackPtr);
+ MachineLocation SPSrc(StackPtr, stackGrowth);
+ Moves.push_back(MachineMove(LabelId, SPDst, SPSrc));
+ }
}
+
+ // Emit DWARF info specifying the offsets of the callee-saved registers.
+ if (PushedRegs)
+ emitCalleeSavedFrameMoves(MF, LabelId, HasFP ? FramePtr : StackPtr);
}
}
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