cmd/compile: improve regalloc live values debug printing

Before:

live values at end of each block
  b1: v3 v2 v7 avoid=0
  b2: v3 v13 avoid=81
  b3: v19[AX] v3 avoid=81
  b6: avoid=0
  b7: avoid=0
  b5: avoid=0
  b4: v3 v18 avoid=81

After:

live values at end of each block
  b1: v3 v2 v7
  b2: v3 v13 avoid=AX DI
  b3: v19[AX] v3 avoid=AX DI
  b6:
  b7:
  b5:
  b4: v3 v18 avoid=AX DI

Change-Id: Ibec5c76a16151832b8d49a21c640699fdc9a9d28
Reviewed-on: https://go-review.googlesource.com/109000
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index 7e35526f19130a26ef19e767d8fb42623af313ca..28cc752b66ff023fd2e4d8109c549e20753c1548 100644 (file)
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -165,6 +165,21 @@ func (m regMask) String() string {
        return s
 }
 
+func (s *regAllocState) RegMaskString(m regMask) string {
+       str := ""
+       for r := register(0); m != 0; r++ {
+               if m>>r&1 == 0 {
+                       continue
+               }
+               m &^= regMask(1) << r
+               if str != "" {
+                       str += " "
+               }
+               str += s.registers[r].String()
+       }
+       return str
+}
+
 // countRegs returns the number of set bits in the register mask.
 func countRegs(r regMask) int {
        n := 0
@@ -793,7 +808,7 @@ func (s *regAllocState) regalloc(f *Func) {
                        }
                }
                if s.f.pass.debug > regDebug {
-                       fmt.Printf("uses for %s:%s\n", s.f.Name, b)
+                       fmt.Printf("use distances for %s\n", b)
                        for i := range s.values {
                                vi := &s.values[i]
                                u := vi.uses
@@ -2400,7 +2415,9 @@ func (s *regAllocState) computeLive() {
                                        fmt.Printf("]")
                                }
                        }
-                       fmt.Printf(" avoid=%x", int64(s.desired[b.ID].avoid))
+                       if avoid := s.desired[b.ID].avoid; avoid != 0 {
+                               fmt.Printf(" avoid=%v", s.RegMaskString(avoid))
+                       }
                        fmt.Println()
                }
        }