constraints.md: Document reserved use of "wc".

2014-03-02  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	* config/rs6000/constraints.md: Document reserved use of "wc".

From-SVN: r208266

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c05694693b060c75c4446fe616f988c37ede34d3..9acf6ec667983c6eda83ce92d46a4e3dad9d27e3 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2014-03-02  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+       * config/rs6000/constraints.md: Document reserved use of "wc".
+
 2014-03-02  Jan Hubicka  <hubicka@ucw.cz>
 
        PR ipa/60150

diff --git a/gcc/config/rs6000/constraints.md b/gcc/config/rs6000/constraints.md
index 50b0e29721468d8e96d09a68f9d2b301bbca0529..50fb101e85c343c1d5b0d25f58425aee4b004762 100644 (file)
--- a/gcc/config/rs6000/constraints.md
+++ b/gcc/config/rs6000/constraints.md
@@ -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.")