[glibc/maskray/unnest] powerpc: Fix unrecognized instruction errors with recent GCC

[glibc/maskray/unnest] powerpc: Fix unrecognized instruction errors with recent GCC

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=064b475a2e5662b6b3973fabf505eade86e61510

commit 064b475a2e5662b6b3973fabf505eade86e61510
Author: Paul A. Clarke <pc@us.ibm.com>
Date:   Tue Sep 14 13:13:33 2021 -0500

    powerpc: Fix unrecognized instruction errors with recent GCC
    
    Recent binutils commit b25f942e18d6ecd7ec3e2d2e9930eb4f996c258a
    changes the behavior of `.machine` directives to override, rather
    than augment, the base CPU. This can result in _reduced_ functionality
    when, for example, compiling for default machine "power8", but explicitly
    asking for ".machine power5", which loses Altivec instructions.
    
    In tst-ucontext-ppc64-vscr.c, while the instructions provoking the new
    error messages are bracketed by ".machine power5", which is ostensibly
    Power ISA 2.03 (POWER5), the POWER5 processor did not support the
    VSX subset, so these instructions are not recognized as "power5".
    
    Error: unrecognized opcode: `vspltisb'
    Error: unrecognized opcode: `vpkuwus'
    Error: unrecognized opcode: `mfvscr'
    Error: unrecognized opcode: `stvx'
    
    Manually adding the VSX subset via ".machine altivec" is sufficient.
    
    Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

Diff:
---
 sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c b/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c
index 28c87fcef7..d3fc4ab589 100644
--- a/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c
+++ b/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c
@@ -50,6 +50,7 @@ do_test (void)
   /* Set SAT bit in VSCR register.  */
   asm volatile (".machine push;\n"
 		".machine \"power5\";\n"
+		".machine altivec;\n"
 		"vspltisb %0,0;\n"
 		"vspltisb %1,-1;\n"
 		"vpkuwus %0,%0,%1;\n"