diff --git a/lib/CodeGen/PreAllocSplitting.cpp b/lib/CodeGen/PreAllocSplitting.cpp index 18cac075d88..1b2b635f393 100644 --- a/lib/CodeGen/PreAllocSplitting.cpp +++ b/lib/CodeGen/PreAllocSplitting.cpp @@ -527,21 +527,23 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) { int SS; unsigned SpillIndex = 0; MachineInstr *SpillMI = NULL; - if (isAlreadySplit(CurrLI->reg, ValNo->id, SS)) { - // If it's already split, just restore the value. There is no need to spill - // the def again. - } else if (ValNo->def == ~0U) { + bool PrevSpilled = isAlreadySplit(CurrLI->reg, ValNo->id, SS); + if (ValNo->def == ~0U) { // If it's defined by a phi, we must split just before the barrier. MachineBasicBlock::iterator SpillPt = findSpillPoint(BarrierMBB, Barrier, RefsInMBB, SpillIndex); if (SpillPt == BarrierMBB->begin()) return false; // No gap to insert spill. // Add spill. - SS = MFI->CreateStackObject(RC->getSize(), RC->getAlignment()); + if (!PrevSpilled) + // If previously split, reuse the spill slot. + SS = MFI->CreateStackObject(RC->getSize(), RC->getAlignment()); TII->storeRegToStackSlot(*BarrierMBB, SpillPt, CurrLI->reg, true, SS, RC); SpillMI = prior(SpillPt); LIs->InsertMachineInstrInMaps(SpillMI, SpillIndex); - } else { + } else if (!PrevSpilled) { + // If it's already split, just restore the value. There is no need to spill + // the def again. // Check if it's possible to insert a spill after the def MI. MachineBasicBlock::iterator SpillPt = findNextEmptySlot(DefMBB, DefMI, SpillIndex); @@ -549,8 +551,8 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) { return false; // No gap to insert spill. SS = MFI->CreateStackObject(RC->getSize(), RC->getAlignment()); - // Add spill. The store instruction kills the register if def is before the - // barrier in the barrier block. + // Add spill. The store instruction kills the register if def is before + // the barrier in the barrier block. TII->storeRegToStackSlot(*DefMBB, SpillPt, CurrLI->reg, DefMBB == BarrierMBB, SS, RC); SpillMI = prior(SpillPt); @@ -567,7 +569,7 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) { // If live interval is spilled in the same block as the barrier, just // create a hole in the interval. if (!DefMBB || - (SpillIndex && SpillMI->getParent() == BarrierMBB)) { + (SpillMI && SpillMI->getParent() == BarrierMBB)) { UpdateIntervalForSplit(ValNo, LIs->getUseIndex(SpillIndex)+1, LIs->getDefIndex(RestoreIndex)); diff --git a/test/CodeGen/X86/pre-split4.ll b/test/CodeGen/X86/pre-split4.ll new file mode 100644 index 00000000000..44ea375a70e --- /dev/null +++ b/test/CodeGen/X86/pre-split4.ll @@ -0,0 +1,24 @@ +; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split -stats |& \ +; RUN: grep {pre-alloc-split} | grep {Number of intervals split} | grep 4 + +define i32 @main(i32 %argc, i8** %argv) nounwind { +entry: + br label %bb + +bb: ; preds = %bb, %entry + %k.0.reg2mem.0 = phi double [ 1.000000e+00, %entry ], [ %6, %bb ] ; [#uses=2] + %Flint.0.reg2mem.0 = phi double [ 0.000000e+00, %entry ], [ %5, %bb ] ; [#uses=1] + %twoThrd.0.reg2mem.0 = phi double [ 0.000000e+00, %entry ], [ %1, %bb ] ; [#uses=1] + %0 = tail call double @llvm.pow.f64(double 0x3FE5555555555555, double 0.000000e+00) ; [#uses=1] + %1 = add double %0, %twoThrd.0.reg2mem.0 ; [#uses=1] + %2 = tail call double @sin(double %k.0.reg2mem.0) nounwind readonly ; [#uses=1] + %3 = mul double 0.000000e+00, %2 ; [#uses=1] + %4 = fdiv double 1.000000e+00, %3 ; [#uses=1] + %5 = add double %4, %Flint.0.reg2mem.0 ; [#uses=1] + %6 = add double %k.0.reg2mem.0, 1.000000e+00 ; [#uses=1] + br label %bb +} + +declare double @llvm.pow.f64(double, double) nounwind readonly + +declare double @sin(double) nounwind readonly