https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103386
Bug ID: 103386
Summary: stage1 with PGO produces bad offsets in rtl-reload on
aarch64
Product: gcc
Version: 11.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mittorn at sibmail dot com
Target Milestone: ---
Created attachment 51862
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51862&action=edit
pgo build logs and system environment
This result in failed conftest binary returning nonzero status when trying to
build libgomp.
Simple program to reproduce conftest behaviour:
int main()
{
return 0;
}
stage1 makes bad assembly on it:
.cfi_startproc
stp x0, x1, [sp, -32]!
.cfi_def_cfa_offset 32
.cfi_offset 0, -32
.cfi_offset 1, -24
stp x2, x3, [sp, 16]
.cfi_offset 2, -16
.cfi_offset 3, -8
mov w0, 0
ldp x2, x3, [sp, 16]
ldp x0, x1, [sp], 32
.cfi_restore 1
.cfi_restore 0
.cfi_restore 2
.cfi_restore 3
.cfi_def_cfa_offset 0
ret
.cfi_endproc
instead of this one:
.cfi_startproc
mov w0, 0
ret
.cfi_endproc
after dumping RTL stages, i found this (source files are identical, second is
stage1):
~ # diff 1.c.292r.reload 2.c.292r.reload
7a8,12
> New elimination table:
> Can eliminate 65 to 31 (offset=32, prev_offset=0)
> Can eliminate 65 to 29 (offset=32, prev_offset=0)
> Can eliminate 64 to 31 (offset=32, prev_offset=0)
> Can eliminate 64 to 29 (offset=32, prev_offset=0)
51,54c56,59
< Can eliminate 65 to 31 (offset=0, prev_offset=0)
< Can eliminate 65 to 29 (offset=0, prev_offset=0)
< Can eliminate 64 to 31 (offset=0, prev_offset=0)
< Can eliminate 64 to 29 (offset=0, prev_offset=0)
---
> Can eliminate 65 to 31 (offset=32, prev_offset=32)
> Can eliminate 65 to 29 (offset=32, prev_offset=0)
> Can eliminate 64 to 31 (offset=32, prev_offset=32)
> Can eliminate 64 to 29 (offset=32, prev_offset=0)
81c86
< (const_int 0 [0])) "1.c":3:8 52 {*movsi_aarch64}
---
> (const_int 0 [0])) "2.c":3:8 52 {*movsi_aarch64}
83c88
< (insn 13 5 15 2 (use (reg/i:SI 0 x0)) "1.c":4:1 -1
---
> (insn 13 5 15 2 (use (reg/i:SI 0 x0)) "2.c":4:1 -1
Full build tree temporary placed here:
http://mittorn.mentality.rip/
needed log and environment info in attachment
