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  1. 23 Jul, 2015 7 commits
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: speed up cse · 8c954d57
      Josh Bleecher Snyder authored 
      By walking only the current set of partitions
at any given point, the cse pass ended up doing
lots of extraneous, effectively O(n^2) work.

Using a regular for loop allows each cse pass to
make as much progress as possible by processing
each new class as it is introduced.

This can and should be optimized further,
but it already reduces by 75% cse time on test/slice3.go.

The overall time to compile test/slice3.go is still
dominated by the O(n^2) work in the liveness pass.
However, Keith is rewriting regalloc anyway.

Change-Id: I8be020b2f69352234587eeadeba923481bf43fcc
Reviewed-on: https://go-review.googlesource.com/12244Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      8c954d57
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: don't combine phi vars from different blocks in CSE · 00437ebe
      Josh Bleecher Snyder authored 
      Here is a concrete case in which this goes wrong.

func f_ssa() int {
	var n int
Next:
	for j := 0; j < 3; j++ {
		for i := 0; i < 10; i++ {
			if i == 6 {
				continue Next
			}
			n = i
		}
		n += j + j + j + j + j + j + j + j + j + j // j * 10
	}
	return n
}

What follows is the function printout before and after CSE.

Note blocks b8 and b10 in the before case.

b8 is the inner loop's condition: i < 10.
b10 is the inner loop's increment: i++.
v82 is i. On entry to b8, it is either 0 (v19) the first time,
or the result of incrementing v82, by way of v29.

The CSE pass considered v82 and v49 to be common subexpressions,
and eliminated v82 in favor of v49.

In the after case, v82 is now dead and will shortly be eliminated.
As a result, v29 is also dead, and we have lost the increment.
The loop runs forever.

BEFORE CSE

f_ssa <nil>
  b1:
    v1 = Arg <mem>
    v2 = SP <uint64>
    v4 = Addr <*int> {~r0} v2
    v13 = Zero <mem> [8] v4 v1
    v14 = Const <int>
    v15 = Const <int>
    v17 = Const <int> [3]
    v19 = Const <int>
    v21 = Const <int> [10]
    v24 = Const <int> [6]
    v28 = Const <int> [1]
    v43 = Const <int> [1]
    Plain -> b3
  b2: <- b7
    Exit v47
  b3: <- b1
    Plain -> b4
  b4: <- b3 b6
    v49 = Phi <int> v15 v44
    v68 = Phi <int> v14 v67
    v81 = Phi <mem> v13 v81
    v18 = Less <bool> v49 v17
    If v18 -> b5 b7
  b5: <- b4
    Plain -> b8
  b6: <- b12 b11
    v67 = Phi <int> v66 v41
    v44 = Add <int> v49 v43
    Plain -> b4
  b7: <- b4
    v47 = Store <mem> v4 v68 v81
    Plain -> b2
  b8: <- b5 b10
    v66 = Phi <int> v68 v82
    v82 = Phi <int> v19 v29
    v22 = Less <bool> v82 v21
    If v22 -> b9 b11
  b9: <- b8
    v25 = Eq <bool> v82 v24
    If v25 -> b12 b13
  b10: <- b13
    v29 = Add <int> v82 v28
    Plain -> b8
  b11: <- b8
    v32 = Add <int> v49 v49
    v33 = Add <int> v32 v49
    v34 = Add <int> v33 v49
    v35 = Add <int> v34 v49
    v36 = Add <int> v35 v49
    v37 = Add <int> v36 v49
    v38 = Add <int> v37 v49
    v39 = Add <int> v38 v49
    v40 = Add <int> v39 v49
    v41 = Add <int> v66 v40
    Plain -> b6
  b12: <- b9
    Plain -> b6
  b13: <- b9
    Plain -> b10

AFTER CSE

f_ssa <nil>
  b1:
    v1 = Arg <mem>
    v2 = SP <uint64>
    v4 = Addr <*int> {~r0} v2
    v13 = Zero <mem> [8] v4 v1
    v14 = Const <int>
    v15 = Const <int>
    v17 = Const <int> [3]
    v19 = Const <int>
    v21 = Const <int> [10]
    v24 = Const <int> [6]
    v28 = Const <int> [1]
    v43 = Const <int> [1]
    Plain -> b3
  b2: <- b7
    Exit v47
  b3: <- b1
    Plain -> b4
  b4: <- b3 b6
    v49 = Phi <int> v19 v44
    v68 = Phi <int> v19 v67
    v81 = Phi <mem> v13 v81
    v18 = Less <bool> v49 v17
    If v18 -> b5 b7
  b5: <- b4
    Plain -> b8
  b6: <- b12 b11
    v67 = Phi <int> v66 v41
    v44 = Add <int> v49 v43
    Plain -> b4
  b7: <- b4
    v47 = Store <mem> v4 v68 v81
    Plain -> b2
  b8: <- b5 b10
    v66 = Phi <int> v68 v49
    v82 = Phi <int> v19 v29
    v22 = Less <bool> v49 v21
    If v22 -> b9 b11
  b9: <- b8
    v25 = Eq <bool> v49 v24
    If v25 -> b12 b13
  b10: <- b13
    v29 = Add <int> v49 v43
    Plain -> b8
  b11: <- b8
    v32 = Add <int> v49 v49
    v33 = Add <int> v32 v49
    v34 = Add <int> v33 v49
    v35 = Add <int> v34 v49
    v36 = Add <int> v35 v49
    v37 = Add <int> v36 v49
    v38 = Add <int> v37 v49
    v39 = Add <int> v38 v49
    v40 = Add <int> v39 v49
    v41 = Add <int> v66 v40
    Plain -> b6
  b12: <- b9
    Plain -> b6
  b13: <- b9
    Plain -> b10

Change-Id: I16fc4ec527ec63f24f7d0d79d1a4a59bf37269de
Reviewed-on: https://go-review.googlesource.com/12444Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      00437ebe
    • Keith Randall's avatar
      [dev.ssa] cmd/compile/internal/ssa: implement multiplies · be1eb57a
      Keith Randall authored 
      Use width-and-signed-specific multiply opcodes.
Implement OMUL.
A few other cleanups.

Fixes #11467

Change-Id: Ib0fe80a1a9b7208dbb8a2b6b652a478847f5d244
Reviewed-on: https://go-review.googlesource.com/12540Reviewed-by: 's avatarJosh Bleecher Snyder <josharian@gmail.com>
      be1eb57a
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: speed up liveness analysis · d5297f72
      Josh Bleecher Snyder authored 
      This reduces the wall time to run test/slice3.go
on my laptop from >10m to ~20s.

This could perhaps be further reduced by using
a worklist of blocks and/or implementing the
suggestion in the comment in this CL, but at this
point, it's fast enough that there is no need.

Change-Id: I741119e0c8310051d7185459f78be8b89237b85b
Reviewed-on: https://go-review.googlesource.com/12564Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      d5297f72
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: add some common binary ops · e61e7c96
      Josh Bleecher Snyder authored 
      Change-Id: I1af486a69960b9b66d5c2c9bbfcf7db6ef075d8c
Reviewed-on: https://go-review.googlesource.com/12563Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      e61e7c96
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: minor cleanup · e0ac5c53
      Josh Bleecher Snyder authored 
      Change-Id: Ib33f3b1cfa09f410675d275e214d8ddc246c53c3
Reviewed-on: https://go-review.googlesource.com/12548Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      e0ac5c53
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: implement control flow handling · 61aa0953
      Josh Bleecher Snyder authored 
      Add label and goto checks and improve test coverage.

Implement OSWITCH and OSELECT.

Implement OBREAK and OCONTINUE.

Allow generation of code in dead blocks.

Change-Id: Ibebb7c98b4b2344f46d38db7c9dce058c56beaac
Reviewed-on: https://go-review.googlesource.com/12445Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      61aa0953
  3. 22 Jul, 2015 2 commits
  5. 21 Jul, 2015 11 commits
  7. 20 Jul, 2015 2 commits
  9. 17 Jul, 2015 1 commit
  11. 16 Jul, 2015 4 commits
  13. 15 Jul, 2015 2 commits
    • Todd Neal's avatar
      [dev.ssa] cmd/compile/internal : Implement Lengauer-Tarjan for dominators · 078ba138
      Todd Neal authored 
      Implements the simple Lengauer-Tarjan algorithm for dominator
and post-dominator calculation.

benchmark                           old ns/op     new ns/op     delta
BenchmarkDominatorsLinear-8         1403862       1292741       -7.92%
BenchmarkDominatorsFwdBack-8        1270633       1428285       +12.41%
BenchmarkDominatorsManyPred-8       225932354     1530886       -99.32%
BenchmarkDominatorsMaxPred-8        445994225     1393612       -99.69%
BenchmarkDominatorsMaxPredVal-8     447235248     1246899       -99.72%
BenchmarkNilCheckDeep1-8            829           1259          +51.87%
BenchmarkNilCheckDeep10-8           2199          2397          +9.00%
BenchmarkNilCheckDeep100-8          57325         29405         -48.70%
BenchmarkNilCheckDeep1000-8         6625837       2933151       -55.73%
BenchmarkNilCheckDeep10000-8        763559787     319105541     -58.21%

benchmark                           old MB/s     new MB/s     speedup
BenchmarkDominatorsLinear-8         7.12         7.74         1.09x
BenchmarkDominatorsFwdBack-8        7.87         7.00         0.89x
BenchmarkDominatorsManyPred-8       0.04         6.53         163.25x
BenchmarkDominatorsMaxPred-8        0.02         7.18         359.00x
BenchmarkDominatorsMaxPredVal-8     0.02         8.02         401.00x
BenchmarkNilCheckDeep1-8            1.21         0.79         0.65x
BenchmarkNilCheckDeep10-8           4.55         4.17         0.92x
BenchmarkNilCheckDeep100-8          1.74         3.40         1.95x
BenchmarkNilCheckDeep1000-8         0.15         0.34         2.27x
BenchmarkNilCheckDeep10000-8        0.01         0.03         3.00x

Change-Id: Icec3d774422a9bc64914779804c8c0ab73aa72bf
Reviewed-on: https://go-review.googlesource.com/11971Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      078ba138
    • Todd Neal's avatar
      [dev.ssa] cmd/compile: implement OIND · b383de2e
      Todd Neal authored 
      Change-Id: I15aee8095e6388822e2222f1995fe2278ac956ca
Reviewed-on: https://go-review.googlesource.com/12129Reviewed-by: 's avatarKeith Randall <khr@golang.org>
Reviewed-by: 's avatarJosh Bleecher Snyder <josharian@gmail.com>
      b383de2e
  15. 14 Jul, 2015 2 commits
  17. 13 Jul, 2015 5 commits
  19. 12 Jul, 2015 4 commits