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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.

28
test/CodeGen/X86/2009-02-12-SpillerBug.ll Normal file
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@ -0,0 +1,28 @@
; RUN: llvm-as < %s | llc -march=x86 -mtriple=i386-apple-darwin8
define hidden void @__mulxc3({ x86_fp80, x86_fp80 }* noalias nocapture sret %agg.result, x86_fp80 %a, x86_fp80 %b, x86_fp80 %c, x86_fp80 %d) nounwind {
entry:
%0 = mul x86_fp80 %b, %d ; <x86_fp80> [#uses=1]
%1 = sub x86_fp80 0xK00000000000000000000, %0 ; <x86_fp80> [#uses=1]
%2 = add x86_fp80 0xK00000000000000000000, 0xK00000000000000000000 ; <x86_fp80> [#uses=1]
%3 = fcmp uno x86_fp80 %1, 0xK00000000000000000000 ; <i1> [#uses=1]
%4 = fcmp uno x86_fp80 %2, 0xK00000000000000000000 ; <i1> [#uses=1]
%or.cond = and i1 %3, %4 ; <i1> [#uses=1]
br i1 %or.cond, label %bb47, label %bb71
bb47: ; preds = %entry
%5 = fcmp uno x86_fp80 %a, 0xK00000000000000000000 ; <i1> [#uses=1]
br i1 %5, label %bb60, label %bb62
bb60: ; preds = %bb47
%6 = tail call x86_fp80 @copysignl(x86_fp80 0xK00000000000000000000, x86_fp80 %a) nounwind readnone ; <x86_fp80> [#uses=0]
br label %bb62
bb62: ; preds = %bb60, %bb47
unreachable
bb71: ; preds = %entry
ret void
}
declare x86_fp80 @copysignl(x86_fp80, x86_fp80) nounwind readnone