i386.md (enabled): Add comment with explanation why fma4 instructions are disabled...

	* config/i386/i386.md (enabled): Add comment with explanation
	why fma4 instructions are disabled for generic code.

From-SVN: r190397

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4f3aa1c111c6e49686de62e431354c15481d3e84..5b2c3d4b983ef5b0dafba248c0ea005ea47ce861 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-08-14  Uros Bizjak  <ubizjak@gmail.com>
+
+       * config/i386/i386.md (enabled): Add comment with explanation
+       why fma4 instructions are disabled for generic code.
+
 2012-08-14  Oleg Endo  <olegendo@gcc.gnu.org>
 
        PR target/52933
@@ -114,7 +119,8 @@
        (verify_phi_args): Likewise.
        (verify_ssa): Likewise.
        * tree-stdarg.c (execute_optimize_stdarg): Likewise.
-       * tree-vect-loop-manip.c (slpeel_update_phi_nodes_for_guard1): Likewise.
+       * tree-vect-loop-manip.c (slpeel_update_phi_nodes_for_guard1):
+       Likewise.
        (slpeel_tree_peel_loop_to_edge): Likewise.
        (vect_can_advance_ivs_p): Likewise.
        (vect_update_ivs_after_vectorizer): Likewise.

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 8d6f211b52f7bd88b2c5afea08751e35d4e8c8f8..16a5c13bea77d9798f38ab4c79106a11bc501edd 100644 (file)
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -659,6 +659,9 @@
         (eq_attr "isa" "noavx2") (symbol_ref "!TARGET_AVX2")
         (eq_attr "isa" "bmi2") (symbol_ref "TARGET_BMI2")
         (eq_attr "isa" "fma") (symbol_ref "TARGET_FMA")
+        ;; Disable generation of FMA4 instructions for generic code
+        ;; since FMA3 is preferred for targets that implement both
+        ;; instruction sets.
         (eq_attr "isa" "fma4")
           (symbol_ref "TARGET_FMA4 && !TARGET_FMA")
        ]