switch the use-vml[as] instructions flag to a subtarget 'feature'
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99565 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARM.td b/lib/Target/ARM/ARM.td
index bbb1dbd..50d54b4 100644
--- a/lib/Target/ARM/ARM.td
+++ b/lib/Target/ARM/ARM.td
@@ -43,6 +43,15 @@
def FeatureFP16 : SubtargetFeature<"fp16", "HasFP16", "true",
"Enable half-precision floating point">;
+// Some processors have multiply-accumulate instructions that don't
+// play nicely with other VFP instructions, and it's generally better
+// to just not use them.
+// FIXME: Currently, this is only flagged for Cortex-A8. It may be true for
+// others as well. We should do more benchmarking and confirm one way or
+// the other.
+def HasSlowVMLx : SubtargetFeature<"vmlx", "SlowVMLx", "true",
+ "Disable VFP MAC instructions">;
+
//===----------------------------------------------------------------------===//
// ARM Processors supported.
//
@@ -106,7 +115,7 @@
// V7 Processors.
def : Processor<"cortex-a8", CortexA8Itineraries,
- [ArchV7A, FeatureThumb2, FeatureNEON]>;
+ [ArchV7A, FeatureThumb2, FeatureNEON, HasSlowVMLx]>;
def : ProcNoItin<"cortex-a9", [ArchV7A, FeatureThumb2, FeatureNEON]>;
//===----------------------------------------------------------------------===//