[PATCH] D22772: GVN-hoist: limit hoisting depth (PR28670)

[Daniel Berlin via llvm-commits]

LGTM


On Mon, Jul 25, 2016 at 3:10 PM, Sebastian Pop <sebpop at gmail.com> wrote:

> sebpop added a comment.
>
> Data from compiling the test-suite for x86_64-linux with -mllvm -stats and
> varying the flag:
> from the RegAlloc metrics we see that the minimum number of spills occurs
> for 100 and starts increasing back at 125.
>
> -gvn-hoist-max-depth=0:
> Number of rematerialized defs for spilling: 18286
> Number of rematerialized defs for splitting: 5727
> Number of spill slots allocated: 44014
> Number of spilled live ranges: 62657
> Number of spills inserted: 51753
> gvn-hoist.*: 0
>
> -gvn-hoist-max-depth=50:
> Number of rematerialized defs for spilling: 18213
> Number of rematerialized defs for splitting: 5827
> Number of spill slots allocated: 43956
> Number of spilled live ranges: 62539
> Number of spills inserted: 51643
> gvn-hoist.*Number of instructions hoisted: 21564
> gvn-hoist.*Number of instructions removed: 30019
> gvn-hoist.*Number of loads hoisted: 14697
> gvn-hoist.*Number of loads removed: 20247
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
> -gvn-hoist-max-depth=100:
> Number of rematerialized defs for spilling: 18223
> Number of rematerialized defs for splitting: 5817
> Number of spill slots allocated: 43961
> Number of spilled live ranges: 62521
> Number of spills inserted: 51623
> gvn-hoist.*Number of instructions hoisted: 21941
> gvn-hoist.*Number of instructions removed: 31106
> gvn-hoist.*Number of loads hoisted: 14951
> gvn-hoist.*Number of loads removed: 21063
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
> -gvn-hoist-max-depth=125:
> Number of rematerialized defs for spilling: 18223
> Number of rematerialized defs for splitting: 5817
> Number of spill slots allocated: 43969
> Number of spilled live ranges: 62520
> Number of spills inserted: 51632
> gvn-hoist.*Number of instructions hoisted: 22044
> gvn-hoist.*Number of instructions removed: 31308
> gvn-hoist.*Number of loads hoisted: 15034
> gvn-hoist.*Number of loads removed: 21221
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
> -gvn-hoist-max-depth=150:
> Number of rematerialized defs for spilling: 18223
> Number of rematerialized defs for splitting: 5817
> Number of spill slots allocated: 43970
> Number of spilled live ranges: 62516
> Number of spills inserted: 51627
> gvn-hoist.*Number of instructions hoisted: 22128
> gvn-hoist.*Number of instructions removed: 31467
> gvn-hoist.*Number of loads hoisted: 15086
> gvn-hoist.*Number of loads removed: 21322
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
> -gvn-hoist-max-depth=200:
> Number of rematerialized defs for spilling: 18223
> Number of rematerialized defs for splitting: 5817
> Number of spill slots allocated: 43993
> Number of spilled live ranges: 62552
> Number of spills inserted: 51661
> gvn-hoist.*Number of instructions hoisted: 22348
> gvn-hoist.*Number of instructions removed: 31864
> gvn-hoist.*Number of loads hoisted: 15200
> gvn-hoist.*Number of loads removed: 21542
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
> -gvn-hoist-max-depth=-1: (i.e., no bounds)
> Number of rematerialized defs for spilling: 18244
> Number of rematerialized defs for splitting: 5817
> Number of spill slots allocated: 44070
> Number of spilled live ranges: 62619
> Number of spills inserted: 51740
> gvn-hoist.*Number of instructions hoisted: 22508
> gvn-hoist.*Number of instructions removed: 32925
> gvn-hoist.*Number of loads hoisted: 15239
> gvn-hoist.*Number of loads removed: 22004
> gvn-hoist.*Number of stores hoisted: 15
> gvn-hoist.*Number of stores removed: 15
> gvn-hoist.*Number of calls hoisted: 8
> gvn-hoist.*Number of calls removed: 8
>
>
> https://reviews.llvm.org/D22772
>
>
>
>
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