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* Add a macro to remove a magic number.

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* Rename variables to reflect what they're actually used for.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145968 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2011-12-06 21:23:42 +00:00
parent f2e944523c
commit 57a3cd2f32
1 changed files with 35 additions and 30 deletions
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65
lib/Target/X86/X86FrameLowering.cpp
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@ -359,12 +359,15 @@ static int getCompactUnwindRegNum(const unsigned *CURegs, unsigned Reg) {
return -1;
}
// Number of registers that can be saved in a compact unwind encoding.
#define CU_NUM_SAVED_REGS 6
/// encodeCompactUnwindRegistersWithoutFrame - Create the permutation encoding
/// used with frameless stacks. It is passed the number of registers to be saved
/// and an array of the registers saved.
static uint32_t encodeCompactUnwindRegistersWithoutFrame(unsigned SavedRegs[6],
unsigned RegCount,
bool Is64Bit) {
static uint32_t
encodeCompactUnwindRegistersWithoutFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS],
unsigned RegCount, bool Is64Bit) {
// The saved registers are numbered from 1 to 6. In order to encode the order
// in which they were saved, we re-number them according to their place in the
// register order. The re-numbering is relative to the last re-numbered
@ -385,16 +388,16 @@ static uint32_t encodeCompactUnwindRegistersWithoutFrame(unsigned SavedRegs[6],
};
const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
for (unsigned i = 6 - RegCount; i < 6; ++i) {
for (unsigned i = CU_NUM_SAVED_REGS - RegCount; i < CU_NUM_SAVED_REGS; ++i) {
int CUReg = getCompactUnwindRegNum(CURegs, SavedRegs[i]);
if (CUReg == -1) return ~0U;
SavedRegs[i] = CUReg;
}
uint32_t RenumRegs[6];
for (unsigned i = 6 - RegCount; i < 6; ++i) {
uint32_t RenumRegs[CU_NUM_SAVED_REGS];
for (unsigned i = CU_NUM_SAVED_REGS - RegCount; i < CU_NUM_SAVED_REGS; ++i) {
unsigned Countless = 0;
for (unsigned j = 6 - RegCount; j < i; ++j)
for (unsigned j = CU_NUM_SAVED_REGS - RegCount; j < i; ++j)
if (SavedRegs[j] < SavedRegs[i])
++Countless;
@ -437,8 +440,9 @@ static uint32_t encodeCompactUnwindRegistersWithoutFrame(unsigned SavedRegs[6],
/// encodeCompactUnwindRegistersWithFrame - Return the registers encoded for a
/// compact encoding with a frame pointer.
static uint32_t encodeCompactUnwindRegistersWithFrame(unsigned SavedRegs[6],
bool Is64Bit) {
static uint32_t
encodeCompactUnwindRegistersWithFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS],
bool Is64Bit) {
static const unsigned CU32BitRegs[] = {
X86::EBX, X86::ECX, X86::EDX, X86::EDI, X86::ESI, X86::EBP, 0
};
@ -477,8 +481,8 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
bool Is64Bit = STI.is64Bit();
bool HasFP = hasFP(MF);
unsigned SavedRegs[6] = { 0, 0, 0, 0, 0, 0 };
int SavedRegIdx = 6;
unsigned SavedRegs[CU_NUM_SAVED_REGS] = { 0, 0, 0, 0, 0, 0 };
int SavedRegIdx = CU_NUM_SAVED_REGS;
unsigned OffsetSize = (Is64Bit ? 8 : 4);
@ -492,8 +496,8 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
unsigned StackDivide = (Is64Bit ? 8 : 4);
unsigned InstrOffset = 0;
unsigned CFAOffset = 0;
unsigned StackAdjust = 0;
unsigned StackSize = 0;
MachineBasicBlock &MBB = MF.front(); // Prologue is in entry BB.
bool ExpectEnd = false;
@ -512,7 +516,7 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
if (--SavedRegIdx < 0) return 0;
SavedRegs[SavedRegIdx] = MI.getOperand(0).getReg();
CFAOffset += OffsetSize;
StackAdjust += OffsetSize;
InstrOffset += PushInstrSize;
} else if (Opc == MoveInstr) {
unsigned SrcReg = MI.getOperand(1).getReg();
@ -521,13 +525,13 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
if (DstReg != FramePtr || SrcReg != StackPtr)
return 0;
CFAOffset = 0;
StackAdjust = 0;
memset(SavedRegs, 0, sizeof(SavedRegs));
SavedRegIdx = 6;
SavedRegIdx = CU_NUM_SAVED_REGS;
InstrOffset += MoveInstrSize;
} else if (Opc == SubtractInstr) {
if (StackAdjust)
// We all ready have a stack pointer adjustment.
if (StackSize)
// We already have a stack size.
return 0;
if (!MI.getOperand(0).isReg() ||
@ -538,7 +542,7 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
// %RSP<def> = SUB64ri8 %RSP, 48
return 0;
StackAdjust = MI.getOperand(2).getImm() / StackDivide;
StackSize = MI.getOperand(2).getImm() / StackDivide;
SubtractInstrIdx += InstrOffset;
ExpectEnd = true;
}
@ -546,9 +550,9 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
// Encode that we are using EBP/RBP as the frame pointer.
uint32_t CompactUnwindEncoding = 0;
CFAOffset /= StackDivide;
StackAdjust /= StackDivide;
if (HasFP) {
if ((CFAOffset & 0xFF) != CFAOffset)
if ((StackAdjust & 0xFF) != StackAdjust)
// Offset was too big for compact encoding.
return 0;
@ -557,17 +561,17 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
if (RegEnc == ~0U) return 0;
CompactUnwindEncoding |= 0x01000000;
CompactUnwindEncoding |= (CFAOffset & 0xFF) << 16;
CompactUnwindEncoding |= (StackAdjust & 0xFF) << 16;
CompactUnwindEncoding |= RegEnc & 0x7FFF;
} else {
if ((CFAOffset & 0xFF) == CFAOffset) {
if ((StackSize & 0xFF) == StackSize) {
// Frameless stack with a small stack size.
CompactUnwindEncoding |= 0x02000000;
// Encode the stack size.
CompactUnwindEncoding |= (CFAOffset & 0xFF) << 16;
CompactUnwindEncoding |= (StackSize & 0xFF) << 16;
} else {
if ((CFAOffset & 0x7) != CFAOffset)
if ((StackAdjust & 0x7) != StackAdjust)
// The extra stack adjustments are too big for us to handle.
return 0;
@ -578,18 +582,19 @@ uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const {
// instruction.
CompactUnwindEncoding |= (SubtractInstrIdx & 0xFF) << 16;
// Encode any extra stack stack changes (done via push instructions).
CompactUnwindEncoding |= (CFAOffset & 0x7) << 13;
// Encode any extra stack stack adjustments (done via push instructions).
CompactUnwindEncoding |= (StackAdjust & 0x7) << 13;
}
// Encode the number of registers saved.
CompactUnwindEncoding |= ((6 - SavedRegIdx) & 0x7) << 10;
CompactUnwindEncoding |= ((CU_NUM_SAVED_REGS - SavedRegIdx) & 0x7) << 10;
// Get the encoding of the saved registers when we don't have a frame
// pointer.
uint32_t RegEnc = encodeCompactUnwindRegistersWithoutFrame(SavedRegs,
6 - SavedRegIdx,
Is64Bit);
uint32_t RegEnc =
encodeCompactUnwindRegistersWithoutFrame(SavedRegs,
CU_NUM_SAVED_REGS - SavedRegIdx,
Is64Bit);
if (RegEnc == ~0U) return 0;
// Encode the register encoding.