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Add a vector to keep track of which registers are allocatable. Remove FIXMEs

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6015 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-05-07 20:08:36 +00:00
parent 8a88563a32
commit 5cdfbad72d
1 changed files with 38 additions and 14 deletions
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52
lib/CodeGen/LiveVariables.cpp
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@ -1,7 +1,22 @@
//===-- LiveVariables.cpp - Live Variable Analysis for Machine Code -------===//
//
// This file implements the LiveVariable analysis pass.
//
// This file implements the LiveVariable analysis pass. For each machine
// instruction in the function, this pass calculates the set of registers that
// are immediately dead after the instruction (i.e., the instruction calculates
// the value, but it is never used) and the set of registers that are used by
// the instruction, but are never used after the instruction (i.e., they are
// killed).
//
// This class computes live variables using are sparse implementation based on
// the machine code SSA form. This class computes live variable information for
// each virtual and _register allocatable_ physical register in a function. It
// uses the dominance properties of SSA form to efficiently compute live
// variables for virtual registers, and assumes that physical registers are only
// live within a single basic block (allowing it to do a single local analysis
// to resolve physical register lifetimes in each basic block). If a physical
// register is not register allocatable, it is not tracked. This is useful for
// things like the stack pointer and condition codes.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveVariables.h"
@ -104,6 +119,23 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
}
bool LiveVariables::runOnMachineFunction(MachineFunction &MF) {
// First time though, initialize AllocatablePhysicalRegisters for the target
if (AllocatablePhysicalRegisters.empty()) {
const MRegisterInfo &MRI = *MF.getTarget().getRegisterInfo();
assert(&MRI && "Target doesn't have register information?");
// Make space, initializing to false...
AllocatablePhysicalRegisters.resize(MRegisterInfo::FirstVirtualRegister);
// Loop over all of the register classes...
for (MRegisterInfo::regclass_iterator RCI = MRI.regclass_begin(),
E = MRI.regclass_end(); RCI != E; ++RCI)
// Loop over all of the allocatable registers in the function...
for (TargetRegisterClass::iterator I = (*RCI)->allocation_order_begin(MF),
E = (*RCI)->allocation_order_end(MF); I != E; ++I)
AllocatablePhysicalRegisters[*I] = true; // The reg is allocatable!
}
// Build BBMap...
unsigned BBNum = 0;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
@ -165,12 +197,8 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &MF) {
if (MO.isVirtualRegister() && !MO.getVRegValueOrNull()) {
unsigned RegIdx = MO.getReg()-MRegisterInfo::FirstVirtualRegister;
HandleVirtRegUse(getVarInfo(RegIdx), MBB, MI);
} else if (MO.isPhysicalRegister() && MO.getReg() != 0
/// FIXME: This is a gross hack, due to us not being able to
/// say that some registers are defined on entry to the
/// function. 5 = ESP
&& MO.getReg() != 5
) {
} else if (MO.isPhysicalRegister() &&
AllocatablePhysicalRegisters[MO.getReg()]) {
HandlePhysRegUse(MO.getReg(), MI);
}
}
@ -193,12 +221,8 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &MF) {
VRInfo.DefBlock = MBB; // Created here...
VRInfo.DefInst = MI;
VRInfo.Kills.push_back(std::make_pair(MBB, MI)); // Defaults to dead
} else if (MO.isPhysicalRegister() && MO.getReg() != 0
/// FIXME: This is a gross hack, due to us not being able to
/// say that some registers are defined on entry to the
/// function. 5 = ESP
&& MO.getReg() != 5
) {
} else if (MO.isPhysicalRegister() &&
AllocatablePhysicalRegisters[MO.getReg()]) {
HandlePhysRegDef(MO.getReg(), MI);
}
}