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From: "tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/105219] [12 Regression] SVE: Wrong code with -O3 -msve-vector-bits=128 -mtune=thunderx
Date: Tue, 12 Apr 2022 12:20:37 +0000 [thread overview]
Message-ID: <bug-105219-4-58ab8DGyV7@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-105219-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105219
--- Comment #8 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
looks like the code out of the vectorizer is fine, and between the two versions
it doesn't change.
The big change is in the unroller, decides to drops one of the BBs for some
reason.
It turns the loop mask phi node from
# loop_mask_374 = PHI <next_mask_416(51), max_mask_372(53), next_mask_378(66),
next_mask_397(68)>
into
# loop_mask_374 = PHI <next_mask_397(51), max_mask_372(53), next_mask_378(66)>
and deletes the BB 68. And indeed -fdisable-tree-cunroll fixes the problem.
It looks like BB68 in the broken version is being marked as unreachable by DFA
and removed.
Curiously with no codegen difference in output of vect, or in dce6 and pcom,
the DFA in cunroll find different number of BBs
good:
Incremental SSA update started at block: 3
Number of blocks in CFG: 88
Number of blocks to update: 37 ( 42%)
Affected blocks: 4 18 28 34 45 47 50 51 53 54 56 58 59 60 61 62 63 64 65 66 67
68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83
bad:
Incremental SSA update started at block: 3
Number of blocks in CFG: 86
Number of blocks to update: 35 ( 41%)
Affected blocks: 4 18 28 34 45 47 50 51 53 54 56 58 59 60 61 62 63 64 65 66 67
68 69 70 71 72 73 74 75 76 77 78 79 80 81
why did it lose 2 BBs?
Is there some info missing from the dump files here?
next prev parent reply other threads:[~2022-04-12 12:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 13:29 [Bug target/105219] New: " acoplan at gcc dot gnu.org
2022-04-11 15:56 ` [Bug target/105219] " tnfchris at gcc dot gnu.org
2022-04-11 16:02 ` ktkachov at gcc dot gnu.org
2022-04-11 16:05 ` acoplan at gcc dot gnu.org
2022-04-11 16:12 ` tnfchris at gcc dot gnu.org
2022-04-12 11:08 ` tnfchris at gcc dot gnu.org
2022-04-12 11:30 ` rguenth at gcc dot gnu.org
2022-04-12 11:36 ` tnfchris at gcc dot gnu.org
2022-04-12 12:20 ` tnfchris at gcc dot gnu.org [this message]
2022-04-13 11:34 ` tnfchris at gcc dot gnu.org
2022-04-13 13:48 ` tnfchris at gcc dot gnu.org
2022-04-20 7:07 ` rguenth at gcc dot gnu.org
2022-04-25 7:07 ` tnfchris at gcc dot gnu.org
2022-04-27 11:56 ` [Bug tree-optimization/105219] " marxin at gcc dot gnu.org
2022-04-27 12:02 ` rguenth at gcc dot gnu.org
2022-04-27 12:06 ` rsandifo at gcc dot gnu.org
2022-04-27 12:27 ` rguenth at gcc dot gnu.org
2022-04-27 12:30 ` rguenth at gcc dot gnu.org
2022-04-27 13:44 ` avieira at gcc dot gnu.org
2022-04-28 8:10 ` cvs-commit at gcc dot gnu.org
2022-04-28 8:10 ` rguenth at gcc dot gnu.org
2022-04-28 12:17 ` rguenth at gcc dot gnu.org
2022-04-29 15:32 ` cvs-commit at gcc dot gnu.org
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