[Mesa-dev] [Bug 32211] [GLSL] lower_jumps with continue-statements in for-loops prevents loop unrolling

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=32211

Timothy Arceri <t_arceri at yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #17 from Timothy Arceri <t_arceri at yahoo.com.au> ---
Should be fixed as of:

commit 9e6b39e1d521aa723749a47d958d58900bf25138 (HEAD -> master, origin/master,
origin/HEAD)
Author: Timothy Arceri <tarceri at itsqueeze.com>
Date:   Mon Nov 26 12:05:00 2018 +1100

    nir: detect more induction variables

    This allows loop analysis to detect inductions variables that
    are incremented in both branches of an if rather than in a main
    loop block. For example:

       loop {
          block block_1:
          /* preds: block_0 block_7 */
          vec1 32 ssa_8 = phi block_0: ssa_4, block_7: ssa_20
          vec1 32 ssa_9 = phi block_0: ssa_0, block_7: ssa_4
          vec1 32 ssa_10 = phi block_0: ssa_1, block_7: ssa_4
          vec1 32 ssa_11 = phi block_0: ssa_2, block_7: ssa_21
          vec1 32 ssa_12 = phi block_0: ssa_3, block_7: ssa_22
          vec4 32 ssa_13 = vec4 ssa_12, ssa_11, ssa_10, ssa_9
          vec1 32 ssa_14 = ige ssa_8, ssa_5
          /* succs: block_2 block_3 */
          if ssa_14 {
             block block_2:
             /* preds: block_1 */
             break
             /* succs: block_8 */
          } else {
             block block_3:
             /* preds: block_1 */
             /* succs: block_4 */
          }
          block block_4:
          /* preds: block_3 */
          vec1 32 ssa_15 = ilt ssa_6, ssa_8
          /* succs: block_5 block_6 */
          if ssa_15 {
             block block_5:
             /* preds: block_4 */
             vec1 32 ssa_16 = iadd ssa_8, ssa_7
             vec1 32 ssa_17 = load_const (0x3f800000 /* 1.000000*/)
             /* succs: block_7 */
          } else {
             block block_6:
             /* preds: block_4 */
             vec1 32 ssa_18 = iadd ssa_8, ssa_7
             vec1 32 ssa_19 = load_const (0x3f800000 /* 1.000000*/)
             /* succs: block_7 */
          }
          block block_7:
          /* preds: block_5 block_6 */
          vec1 32 ssa_20 = phi block_5: ssa_16, block_6: ssa_18
          vec1 32 ssa_21 = phi block_5: ssa_17, block_6: ssa_4
          vec1 32 ssa_22 = phi block_5: ssa_4, block_6: ssa_19
          /* succs: block_1 */
       }

    Unfortunatly GCM could move the addition out of the if for us
    (making this patch unrequired) but we still cannot enable the GCM
    pass without regressions.

    This unrolls a loop in Rise of The Tomb Raider.

    vkpipeline-db results (VEGA):

    Totals from affected shaders:
    SGPRS: 88 -> 96 (9.09 %)
    VGPRS: 56 -> 52 (-7.14 %)
    Spilled SGPRs: 0 -> 0 (0.00 %)
    Spilled VGPRs: 0 -> 0 (0.00 %)
    Private memory VGPRs: 0 -> 0 (0.00 %)
    Scratch size: 0 -> 0 (0.00 %) dwords per thread
    Code Size: 2168 -> 4560 (110.33 %) bytes
    LDS: 0 -> 0 (0.00 %) blocks
    Max Waves: 4 -> 4 (0.00 %)
    Wait states: 0 -> 0 (0.00 %)

    Reviewed-by: Thomas Helland <thomashelland90 at gmail.com>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=32211

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