ARM cortex-a8 doesn't do vmla/vmls well. disable them by default for that cpu

llvm-svn: 99549

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 6b4438d4c86..8df59e4789e 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -127,6 +127,12 @@ ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
     // operations with NEON instructions.
     if (UseNEONFP.getPosition() == 0)
       UseNEONForSinglePrecisionFP = true;
+    // The VFP vlma and vlms instructions don't play nicely with others;
+    // disable them.
+    // FIXME: This may be true for other variants as well. Get benchmark
+    // numbers and add them if determined that's the case.
+    if (UseVMLxInstructions.getPosition() == 0)
+      UseVMLx = false;
   }
 }