diff options
| -rw-r--r-- | src/cmd/compile/internal/ssa/regalloc.go | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go index 8abbf61507..e92ab00e95 100644 --- a/src/cmd/compile/internal/ssa/regalloc.go +++ b/src/cmd/compile/internal/ssa/regalloc.go @@ -976,25 +976,22 @@ func (s *regAllocState) regalloc(f *Func) { } } - // Second pass - deallocate any phi inputs which are now dead. + // Second pass - deallocate all in-register phi inputs. for i, v := range phis { if !s.values[v.ID].needReg { continue } a := v.Args[idx] - if !regValLiveSet.contains(a.ID) { - // Input is dead beyond the phi, deallocate - // anywhere else it might live. - s.freeRegs(s.values[a.ID].regs) - } else { - // Input is still live. + r := phiRegs[i] + if r == noRegister { + continue + } + if regValLiveSet.contains(a.ID) { + // Input value is still live (it is used by something other than Phi). // Try to move it around before kicking out, if there is a free register. // We generate a Copy in the predecessor block and record it. It will be - // deleted if never used. - r := phiRegs[i] - if r == noRegister { - continue - } + // deleted later if never used. + // // Pick a free register. At this point some registers used in the predecessor // block may have been deallocated. Those are the ones used for Phis. Exclude // them (and they are not going to be helpful anyway). @@ -1010,8 +1007,8 @@ func (s *regAllocState) regalloc(f *Func) { s.assignReg(r2, a, c) s.endRegs[p.ID] = append(s.endRegs[p.ID], endReg{r2, a, c}) } - s.freeReg(r) } + s.freeReg(r) } // Copy phi ops into new schedule. @@ -1842,6 +1839,11 @@ func (s *regAllocState) shuffle(stacklive [][]ID) { e.process() } } + + if s.f.pass.debug > regDebug { + fmt.Printf("post shuffle %s\n", s.f.Name) + fmt.Println(s.f.String()) + } } type edgeState struct { |