diff options
Diffstat (limited to 'src/cmd/compile/internal/ssa/regalloc.go')
| -rw-r--r-- | src/cmd/compile/internal/ssa/regalloc.go | 47 |
1 files changed, 32 insertions, 15 deletions
diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go index 2590315ba1..6ffa1e3848 100644 --- a/src/cmd/compile/internal/ssa/regalloc.go +++ b/src/cmd/compile/internal/ssa/regalloc.go @@ -701,8 +701,10 @@ func (s *regAllocState) init(f *Func) { for _, b := range f.Blocks { // New block. Clear candidate set. canLiveOnStack.clear() - if b.Control != nil && b.Control.Uses == 1 && !opcodeTable[b.Control.Op].generic { - canLiveOnStack.add(b.Control.ID) + for _, c := range b.ControlValues() { + if c.Uses == 1 && !opcodeTable[c.Op].generic { + canLiveOnStack.add(c.ID) + } } // Walking backwards. for i := len(b.Values) - 1; i >= 0; i-- { @@ -856,9 +858,11 @@ func (s *regAllocState) regalloc(f *Func) { s.addUse(e.ID, int32(len(b.Values))+e.dist, e.pos) // pseudo-uses from beyond end of block regValLiveSet.add(e.ID) } - if v := b.Control; v != nil && s.values[v.ID].needReg { - s.addUse(v.ID, int32(len(b.Values)), b.Pos) // pseudo-use by control value - regValLiveSet.add(v.ID) + for _, v := range b.ControlValues() { + if s.values[v.ID].needReg { + s.addUse(v.ID, int32(len(b.Values)), b.Pos) // pseudo-use by control values + regValLiveSet.add(v.ID) + } } for i := len(b.Values) - 1; i >= 0; i-- { v := b.Values[i] @@ -1503,21 +1507,32 @@ func (s *regAllocState) regalloc(f *Func) { issueSpill: } - // Load control value into reg. - if v := b.Control; v != nil && s.values[v.ID].needReg { + // Copy the control values - we need this so we can reduce the + // uses property of these values later. + controls := append(make([]*Value, 0, 2), b.ControlValues()...) + + // Load control values into registers. + for i, v := range b.ControlValues() { + if !s.values[v.ID].needReg { + continue + } if s.f.pass.debug > regDebug { fmt.Printf(" processing control %s\n", v.LongString()) } // We assume that a control input can be passed in any // type-compatible register. If this turns out not to be true, // we'll need to introduce a regspec for a block's control value. - b.Control = s.allocValToReg(v, s.compatRegs(v.Type), false, b.Pos) - if b.Control != v { - v.Uses-- - b.Control.Uses++ + b.ReplaceControl(i, s.allocValToReg(v, s.compatRegs(v.Type), false, b.Pos)) + } + + // Reduce the uses of the control values once registers have been loaded. + // This loop is equivalent to the advanceUses method. + for _, v := range controls { + vi := &s.values[v.ID] + if !vi.needReg { + continue } // Remove this use from the uses list. - vi := &s.values[v.ID] u := vi.uses vi.uses = u.next if u.next == nil { @@ -2355,9 +2370,11 @@ func (s *regAllocState) computeLive() { live.set(e.ID, e.dist+int32(len(b.Values)), e.pos) } - // Mark control value as live - if b.Control != nil && s.values[b.Control.ID].needReg { - live.set(b.Control.ID, int32(len(b.Values)), b.Pos) + // Mark control values as live + for _, c := range b.ControlValues() { + if s.values[c.ID].needReg { + live.set(c.ID, int32(len(b.Values)), b.Pos) + } } // Propagate backwards to the start of the block |