https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117838
Bug ID: 117838
Summary: IRA issues: The higher cost variable a is spilled for
the lower cost variable conflict_a in
improve_allocatuion()
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: lili.cui at intel dot com
Target Milestone: ---
Created attachment 59740
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59740&action=edit
testcase-dump-patch
testcase : sqlite3-ok.i (in attachment, It is extracted from SQLite)
gcc version: Fri Oct 18 2024 (aaa855fac0c7003d823b48fe4cc4b9ded9331a2b)
compile options : -std=c18 -m64 -S -o sqlite3.s -Ofast -march=x86-64-v3
sqlite3-ok.i -da
Function: sqlite3VdbeExec
variable a : pOp -> a5(r806, l0) cost=30495
variable conflict_a : nDepth -> a2737(r1214,l0) cost 1102
Pushing a5(r806,l0)(potential spill: pri=26, cost=30495)
Pushing a2737(r1214,l0: a2656(r1214,l2: a1251(r1214,l17)))(cost 1102)
Popping a5(r806,l0) -- assign reg 40
Popping a2737(r1214,l0: a2656(r1214,l2: a1251(r1214,l17))) -- assign reg 38
Spilling a5r806 for a2737r1214
Assigning 40 to a2737r1214
a5(r806,l0) -- assign memory
It was introduced by the following commit:
commit 037cc0b4a6646cc86549247a3590215ebd5c4c43
Author: Richard Sandiford <[email protected]>
Date: Mon Jan 10 14:47:09 2022 +0000
ira: Handle "soft" conflicts between cap and non-cap allocnos
I created a patch (in attachment) to drop the issue code, there is no
regression on graviton 3 and SPR with speccpu2017.
