6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-04-06 09:44:39 +00:00
Code Issues Projects Releases Wiki Activity

* Redo the permutation encoding for frameless stacks to be more like what the

Browse Source 
unwind library expects.
* Comment the permutation encoding for frameless stacks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135202 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2011-07-14 22:01:34 +00:00
parent 3dcb4ef757
commit 13123d9463
1 changed files with 71 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
lib/Target/X86/X86FrameLowering.cpp
View File

@ -1031,45 +1031,67 @@ X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
}
}
/// permuteEncode - 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 permuteEncode(unsigned SavedCount, unsigned Registers[6]) {
uint32_t RenumRegs[6];
for (int i = 6 - SavedCount; i < 6; ++i) {
int countless = 0;
for (int j = 6 - SavedCount; j < i; ++j)
if (Registers[j] < Registers[i])
++countless;
// 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
// register. E.g., if we have registers {6, 2, 4, 5} saved in that order:
//
// Orig Re-Num
// ---- ------
// 6 6
// 2 2
// 4 3
// 5 3
//
bool Used[7] = { false, false, false, false, false, false, false };
uint32_t RenumRegs[6];
for (unsigned I = 0; I < SavedCount; ++I) {
uint32_t Renum = 0;
for (unsigned U = 1; U < 7; ++U) {
if (U == Registers[I])
break;
if (!Used[U])
++Renum;
}
RenumRegs[i] = Registers[i] - countless - 1;
}
Used[Registers[I]] = true;
RenumRegs[I] = Renum;
}
uint32_t permutationEncoding = 0;
switch (SavedCount) {
case 6:
permutationEncoding |= 120 * RenumRegs[0] + 24 * RenumRegs[1]
+ 6 * RenumRegs[2] + 2 * RenumRegs[3]
+ RenumRegs[4];
break;
case 5:
permutationEncoding |= 120 * RenumRegs[1] + 24 * RenumRegs[2]
+ 6 * RenumRegs[3] + 2 * RenumRegs[4]
+ RenumRegs[5];
break;
case 4:
permutationEncoding |= 60 * RenumRegs[2] + 12 * RenumRegs[3]
+ 3 * RenumRegs[4] + RenumRegs[5];
break;
case 3:
permutationEncoding |= 20 * RenumRegs[3] + 4 * RenumRegs[4]
+ RenumRegs[5];
break;
case 2:
permutationEncoding |= 5 * RenumRegs[4] + RenumRegs[5];
break;
case 1:
permutationEncoding |= RenumRegs[5];
break;
}
return permutationEncoding;
// Take the renumbered values and encode them into a 10-bit number.
uint32_t permutationEncoding = 0;
switch (SavedCount) {
case 6:
permutationEncoding |= 120 * RenumRegs[0] + 24 * RenumRegs[1]
+ 6 * RenumRegs[2] + 2 * RenumRegs[3]
+ RenumRegs[4];
break;
case 5:
permutationEncoding |= 120 * RenumRegs[0] + 24 * RenumRegs[1]
+ 6 * RenumRegs[2] + 2 * RenumRegs[3]
+ RenumRegs[4];
break;
case 4:
permutationEncoding |= 60 * RenumRegs[0] + 12 * RenumRegs[1]
+ 3 * RenumRegs[2] + RenumRegs[3];
break;
case 3:
permutationEncoding |= 20 * RenumRegs[0] + 4 * RenumRegs[1]
+ RenumRegs[2];
break;
case 2:
permutationEncoding |= 5 * RenumRegs[0] + RenumRegs[1];
break;
case 1:
permutationEncoding |= RenumRegs[0];
break;
}
return permutationEncoding;
}
uint32_t X86FrameLowering::
@ -1104,12 +1126,12 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
if (Src.getReg() != MachineLocation::VirtualFP) {
// DW_CFA_def_cfa
assert(FramePointerReg == -1 &&"Defining more than one frame pointer?");
FramePointerReg = Src.getReg();
if (TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::EBP &&
TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::RBP)
if (TRI->getLLVMRegNum(Src.getReg(), IsEH) != X86::EBP &&
TRI->getLLVMRegNum(Src.getReg(), IsEH) != X86::RBP)
// The frame pointer isn't EBP/RBP. Cannot make unwind information
// compact.
return 0;
FramePointerReg = TRI->getCompactUnwindRegNum(Src.getReg(), IsEH);
} // else DW_CFA_def_cfa_offset
if (IsRelative)
@ -1123,12 +1145,19 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
// DW_CFA_def_cfa_register
assert(FramePointerReg == -1 && "Defining more than one frame pointer?");
FramePointerReg = Dst.getReg();
if (TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::EBP &&
TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::RBP)
if (TRI->getLLVMRegNum(Dst.getReg(), IsEH) != X86::EBP &&
TRI->getLLVMRegNum(Dst.getReg(), IsEH) != X86::RBP)
// The frame pointer isn't EBP/RBP. Cannot make unwind information
// compact.
return 0;
FramePointerReg = TRI->getCompactUnwindRegNum(Dst.getReg(), IsEH);
if (SavedRegIdx != 1 || SavedRegs[0] != unsigned(FramePointerReg))
return 0;
SavedRegs[0] = 0;
SavedRegIdx = 0;
continue;
}