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It's (currently) not safe to keep certain physical registers live across basic blocks, e.g. x86 fp stack registers.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64374 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-02-12 10:32:17 +00:00
parent f2b14715d1
commit 8679119f4b
2 changed files with 40 additions and 2 deletions
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14
lib/CodeGen/VirtRegMap.cpp
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@@ -496,6 +496,12 @@ void AvailableSpills::AddAvailableRegsToLiveIn(MachineBasicBlock &MBB) {
I = PhysRegsAvailable.begin(), E = PhysRegsAvailable.end();
I != E; ++I) {
unsigned Reg = (*I).first;
const TargetRegisterClass* RC = TRI->getPhysicalRegisterRegClass(Reg);
// FIXME: A temporary workaround. We can't reuse available value if it's
// not safe to move the def of the virtual register's class. e.g.
// X86::RFP* register classes. Do not add it as a live-in.
if (!TII->isSafeToMoveRegClassDefs(RC))
continue;
if (!MBB.isLiveIn(Reg))
MBB.addLiveIn(Reg);
}
@@ -1361,7 +1367,12 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
bool DoReMat = VRM.isReMaterialized(VirtReg);
int SSorRMId = DoReMat
? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
// FIXME: A temporary workaround. Don't reuse available value if it's
// not safe to move the def of the virtual register's class. e.g.
// X86::RFP* register classes.
unsigned InReg = TII->isSafeToMoveRegClassDefs(RC) ?
Spills.getSpillSlotOrReMatPhysReg(SSorRMId) : 0;
if (InReg == Phys) {
// If the value is already available in the expected register, save
// a reload / remat.
@@ -1387,7 +1398,6 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
// If the reloaded / remat value is available in another register,
// copy it to the desired register.
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
TII->copyRegToReg(MBB, &MI, Phys, InReg, RC, RC);
// This invalidates Phys.