From: cinap_lenrek@felloff.net
To: 9front@9front.org
Subject: Re: arm64 fails to link when float converted to int (Was Re: [9front] netsurf native frontend (text_insert: illegal combination FCVTZSDW FCON NONE REG))
Date: Sat, 1 Aug 2020 13:43:06 +0200 [thread overview]
Message-ID: <8BFCD64ADCEA9E2631D9323B893FF9A2@felloff.net> (raw)
In-Reply-To: <AB617CEA-B63A-4CAC-A5C0-E4C0D2F05F18@cpan.org>
this is clearly a compiler bug.
lets compare with the other compilers:
term% for(i in 5c 7c 8c){echo $i; $i -o/dev/null -S a.c}
5c
TEXT main+0(SB),0,$8
MOVW $1,R1
MOVD $1.50000000000000000e+00,F0
MOVWD R1,F1 <- convert lhs to float
MULD F0,F1 <- do floatingpoint multiplication
MOVDW F1,R3 <- convert result back to integer
MOVW $0,R0
BL ,exits+0(SB)
RET ,
END ,
7c
TEXT main+0(SB),0,$16
MOVW $1,R1
FCVTZSDW $1.50000000000000000e+00,R2 <- tries to convert rhs to int??
MULW R2,R1,R2 <- multiplication done in int? bug!
MOV $0,R0
BL ,exits+0(SB)
RETURN ,
END ,
8c
TEXT main+0(SB),0,$20
MOVL $1,size+-4(SP)
FMOVD $(1.50000000000000000e+00),F0
FMOVL size+-4(SP),F0 <- convert lhs to float
FMULDP F0,F1 <- do floatingpoint multiplication
FSTCW ,.safe+-16(SP)
MOVW $3967,.safe+-14(SP)
FLDCW .safe+-14(SP), <- hahahaha, thanks intel!
FMOVLP F0,.safe+-12(SP)
FLDCW .safe+-16(SP),
MOVL .safe+-12(SP),AX <- convert result back to integer
MOVL $0,(SP)
CALL ,exits+0(SB)
RET ,
END ,
we have to do the operation using the type of the right hand side:
diff -r f8f63e944375 sys/src/cmd/7c/cgen.c
--- a/sys/src/cmd/7c/cgen.c Fri Jul 17 16:53:20 2020 +0200
+++ b/sys/src/cmd/7c/cgen.c Sat Aug 01 13:33:09 2020 +0200
@@ -287,10 +287,10 @@
reglcgen(&nod2, l, Z);
else
nod2 = *l;
- regalloc(&nod, n, nn);
+ regalloc(&nod, r, nn);
cgen(r, &nod);
} else {
- regalloc(&nod, n, nn);
+ regalloc(&nod, r, nn);
cgen(r, &nod);
if(l->addable < INDEXED)
reglcgen(&nod2, l, Z);
with that change, 7c properly does the multiplication in floating
point, and converts the result back to integer:
term% /sys/src/cmd/7c/6.out -o/dev/null -S a.c
TEXT main+0(SB),0,$16
MOVW $1,R1
FMOVD $1.50000000000000000e+00,F1
SCVTFWD R1,F4 <- convert left hand side to float
FMULD F1,F4,F1 <- do floatingpoint multiplication
FCVTZSDW F1,R1 <- convert result back to integer
MOV $0,R0
BL ,exits+0(SB)
RETURN ,
END ,
we'll need to to do a bunch of test now to make sure this
change doesnt break anything.
feel free to test and report any errors would be appreciated.
--
cinap
next prev parent reply other threads:[~2020-08-01 11:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 15:54 netsurf native frontend telephil9
2020-05-21 16:06 ` [9front] " hiro
2020-05-21 17:59 ` Romano
2020-07-28 7:11 ` [9front] netsurf native frontend (text_insert: illegal combination FCVTZSDW FCON NONE REG) Romano
2020-07-29 6:08 ` arm64 fails to link when float converted to int (Was Re: [9front] netsurf native frontend (text_insert: illegal combination FCVTZSDW FCON NONE REG)) Romano
2020-08-01 11:43 ` cinap_lenrek [this message]
2020-08-01 12:23 ` Anthony Martin
2020-05-21 21:16 ` [9front] netsurf native frontend Dave MacFarlane
2020-05-23 11:03 ` telephil9
2020-05-23 15:42 ` Stanley Lieber
2020-05-23 16:13 ` Stanley Lieber
2020-05-23 4:08 ` kokamoto
2020-05-23 6:13 ` Eli Cohen
2020-05-23 6:18 ` telephil9
2020-05-23 6:37 ` Eli Cohen
2020-05-23 20:10 ` jamos
2020-05-24 0:02 ` kokamoto
2020-05-25 3:51 ` kokamoto
2020-05-24 2:13 ` sl
2020-08-01 18:41 arm64 fails to link when float converted to int (Was Re: [9front] netsurf native frontend (text_insert: illegal combination FCVTZSDW FCON NONE REG)) Romano
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