Disable FMA by default. Use -Ofma or jit.opt.start("+fma") to enable.

See the discussion in #918 for the rationale.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/lj_jit.h b/src/lj_jit.h
index 32b3861a..7f081730 100644
--- a/src/lj_jit.h
+++ b/src/lj_jit.h
@@ -87,10 +87,11 @@
 #define JIT_F_OPT_ABC           (JIT_F_OPT << 7)
 #define JIT_F_OPT_SINK          (JIT_F_OPT << 8)
 #define JIT_F_OPT_FUSE          (JIT_F_OPT << 9)
+#define JIT_F_OPT_FMA           (JIT_F_OPT << 10)
 
 /* Optimizations names for -O. Must match the order above. */
 #define JIT_F_OPTSTRING \
-  "\4fold\3cse\3dce\3fwd\3dse\6narrow\4loop\3abc\4sink\4fuse"
+  "\4fold\3cse\3dce\3fwd\3dse\6narrow\4loop\3abc\4sink\4fuse\3fma"
 
 /* Optimization levels set a fixed combination of flags. */
 #define JIT_F_OPT_0     0
@@ -99,6 +100,7 @@
 #define JIT_F_OPT_3     (JIT_F_OPT_2|\
   JIT_F_OPT_FWD|JIT_F_OPT_DSE|JIT_F_OPT_ABC|JIT_F_OPT_SINK|JIT_F_OPT_FUSE)
 #define JIT_F_OPT_DEFAULT       JIT_F_OPT_3
+/* Note: FMA is not set by default. */
 
 /* -- JIT engine parameters ----------------------------------------------- */