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[PATCH, rs6000] Document reserved use of "wc" constraint
- From: Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: dje dot gcc at gmail dot com
- Date: Fri, 28 Feb 2014 18:23:31 -0600
- Subject: [PATCH, rs6000] Document reserved use of "wc" constraint
- Authentication-results: sourceware.org; auth=none
Hi,
Hal Finkel requested that we define a constraint for representing
individual CR bits. We agreed to reserve "wc" for this purpose to
maintain compatibility with LLVM. This patch documents that use.
A pro-forma regstrap is in progress. Assuming no problems, is this ok
for trunk?
Thanks,
Bill
2014-02-28 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
* config/rs6000/constraints.md: Document reserved use of "wc".
Index: gcc/config/rs6000/constraints.md
===================================================================
--- gcc/config/rs6000/constraints.md (revision 208237)
+++ gcc/config/rs6000/constraints.md (working copy)
@@ -56,6 +56,9 @@
(define_register_constraint "wa" "rs6000_constraints[RS6000_CONSTRAINT_wa]"
"Any VSX register if the -mvsx option was used or NO_REGS.")
+;; NOTE: For compatibility, "wc" is reserved to represent individual CR bits.
+;; It is currently used for that purpose in LLVM.
+
(define_register_constraint "wd" "rs6000_constraints[RS6000_CONSTRAINT_wd]"
"VSX vector register to hold vector double data or NO_REGS.")