Re: [PATCH] convert braced initializers to strings (PR 71625)

[Martin Sebor <msebor at gmail dot com>]

On 08/15/2018 06:07 AM, Joseph Myers wrote:
> On Tue, 14 Aug 2018, Martin Sebor wrote:
>
> > > This is with Bison 3.0.4, should the version used to produce intl/plural.c
> > > prove relevant.
> >
> > Can you send me the translation unit and the options it was compiled
> > with that triggered the errors?
>
> I've attached plural.i.  The error is a static link error linking sln, but
> maybe comparing results of compiling plural.i before and after the changes
> may be enlightening (unless it's actually a difference in code elsewhere
> in glibc causing a link error reported in plural.o).
>
> Compiled with:
>
> alpha-glibc-linux-gnu-gcc
> /scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/intl/plural.c
> -c -std=gnu11 -fgnu89-inline  -O2 -Wall -Werror -Wundef -Wwrite-strings
> -fmerge-all-constants -fno-stack-protector -frounding-math -g
> -Wstrict-prototypes -Wold-style-definition -fno-math-errno
> -mlong-double-128 -mieee -mfp-rounding-mode=d     -ftls-model=initial-exec
> -I../include
> -I/scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/intl
> -I/scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu
> -I../sysdeps/unix/sysv/linux/alpha/alpha
> -I../sysdeps/unix/sysv/linux/alpha/fpu  -I../sysdeps/alpha/fpu
> -I../sysdeps/unix/sysv/linux/alpha  -I../sysdeps/alpha/nptl
> -I../sysdeps/unix/sysv/linux/wordsize-64  -I../sysdeps/ieee754/ldbl-64-128
> -I../sysdeps/ieee754/ldbl-opt  -I../sysdeps/unix/sysv/linux/include
> -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread
> -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv
> -I../sysdeps/unix/alpha  -I../sysdeps/unix  -I../sysdeps/posix
> -I../sysdeps/alpha  -I../sysdeps/wordsize-64
> -I../sysdeps/ieee754/ldbl-128  -I../sysdeps/ieee754/dbl-64/wordsize-64
> -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32
> -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I.
> -D_LIBC_REENTRANT -include
> /scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/libc-modules.h
> -DMODULE_NAME=libc -include ../include/libc-symbols.h
> -DTOP_NAMESPACE=glibc -D'LOCALEDIR="/usr/share/locale"'
> -D'LOCALE_ALIAS_PATH="/usr/share/locale"' -o
> /scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/intl/plural.o
> -MD -MP -MF
> /scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/intl/plural.o.dt
> -MT
> /scratch/jmyers/glibc/many9/build/compilers/alpha-linux-gnu/glibc/alpha-linux-gnu/intl/plural.o

Thanks.  I don't see anything obviously wrong but I don't know
much about Alpha assembly.  Attached are the two .s files, with
(plural-new.s) and without (plural-old.s) the array-to-string
transformation.

There are also only a handful of transformed arrays in the file
and they all look reasonable to me (see the attachment named
plural-array-to-string.txt).  The only arrays in the .sdata
section are yydefgoto and yypgoto, both before and after.
They are each just 3 bytes in size.

There is one unusual difference in the loads of one of them in
the assembly emitted by GCC for __gettextparse.

Before:

	ldah $22,yypgoto($29)				!gprelhigh
	...
	lda $2,yypgoto($22)				!gprellow

After:

	ldah $2,yypgoto+2305843009213693936($29)	!gprelhigh
	...
	lda $2,yypgoto+2305843009213693936($2)		!gprellow

I don't know if it's significant -- the lda instruction uses
just the least significant 16 bits of the constant displacement,
shifted left by 16.  I don't see any obviously bogus constants
in the disassembly produced by objdump.

I'll need some help from someone who knows more about Alpha
to understand what's going on.

Martin

Attachment: plural-old.s
Description: Text document

Attachment: plural-new.s
Description: Text document

Attachment: plural-array-to-string.txt
Description: Text document