From 6a116f140f8921880516df7bcfb62fb6a3db033a Mon Sep 17 00:00:00 2001 From: Michael Meissner Date: Wed, 10 Jun 2015 16:51:49 +0000 Subject: [PATCH] re PR target/66474 (Document the use of %x in powerpc asm statements) 2015-06-10 Michael Meissner PR target/66474 * doc/md.texi (Machine Constraints): Document that on the PowerPC if you use a constraint that targets a VSX register, you must use %x in the template. From-SVN: r224332 --- gcc/ChangeLog | 7 +++++++ gcc/doc/md.texi | 21 +++++++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 7c002a4e929..e4dfe3856ec 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2015-06-10 Michael Meissner + + PR target/66474 + * doc/md.texi (Machine Constraints): Document that on the PowerPC + if you use a constraint that targets a VSX register, you must use + %x in the template. + 2015-06-10 Max Filippov * config/xtensa/xtensa.h (TARGET_DEBUG): New definition. diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index 30d7775aba7..e991286afcc 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -3070,6 +3070,27 @@ Altivec vector register @item wa Any VSX register if the -mvsx option was used or NO_REGS. +When using any of the register constraints (@code{wa}, @code{wd}, +@code{wf}, @code{wg}, @code{wh}, @code{wi}, @code{wj}, @code{wk}, +@code{wl}, @code{wm}, @code{ws}, @code{wt}, @code{wu}, @code{wv}, +@code{ww}, or @code{wy}) that take VSX registers, you must use +@code{%x} in the template so that the correct register is used. +Otherwise the register number output in the assembly file will be +incorrect if an Altivec register is an operand of a VSX instruction +that expects VSX register numbering. + +@smallexample +asm ("xvadddp %x0,%x1,%x2" : "=wa" (v1) : "wa" (v2), "wa" (v3)); +@end smallexample + +is correct, but: + +@smallexample +asm ("xvadddp %0,%1,%2" : "=wa" (v1) : "wa" (v2), "wa" (v3)); +@end smallexample + +is not correct. + @item wd VSX vector register to hold vector double data or NO_REGS. -- 2.30.2