PR/59391 CVS commit: src

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

The following reply was made to PR lib/59391; it has been noted by GNATS.

From: "Taylor R Campbell" <riastradh%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/59391 CVS commit: src
Date: Sat, 3 May 2025 19:57:13 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Sat May  3 19:57:13 UTC 2025
 
 Modified Files:
 	src/lib/libc/arch/arm/gen: _setjmp.S setjmp.S
 	src/lib/libc/arch/arm/sys: cerror.S ptrace.S sbrk.S
 	src/sys/arch/arm/include: asm.h
 
 Log Message:
 arm: Nix most __PIC__ conditionals in .S files.
 
 New macros PCREL_GET(rN,label,pclabel) and PCREL_SYM(label,pclabel)
 to enable this by the pattern:
 
 	ldr	rN, label
 #ifdef __PIC__
 pclabel:
 	add	rN, rN, pc
 #endif
 ...
 label:
 #ifdef __PIC__
 	.word	(label - (pclabel + 2*sizeof(instruction)))
 #else
 	.word	label
 #endif
 
 (sizeof(instruction) = 2 for thumb, 4 for non-thumb.)
 
 No binary change in libc with MKPIE=no (i.e., testing both for
 changes to the PIC build and changes to the non-PIC build).
 
 In principle, assembly routines could improve instruction scheduling
 by splitting up the ldr and add instructions.  But in practice, the
 maintenance and auditing burden likely makes this worthwhile by
 improving legibility vs a tangle of in-line #ifdefs.
 
 brk.S does things a little differently making it harder to unify.
 Could redo it but I don't want to make changes without testing them
 first.
 
 PR lib/59391: unnecessary __PIC__ conditionals clutter .S files
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.17 -r1.18 src/lib/libc/arch/arm/gen/_setjmp.S
 cvs rdiff -u -r1.19 -r1.20 src/lib/libc/arch/arm/gen/setjmp.S
 cvs rdiff -u -r1.13 -r1.14 src/lib/libc/arch/arm/sys/cerror.S
 cvs rdiff -u -r1.12 -r1.13 src/lib/libc/arch/arm/sys/ptrace.S \
     src/lib/libc/arch/arm/sys/sbrk.S
 cvs rdiff -u -r1.35 -r1.36 src/sys/arch/arm/include/asm.h
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.