Add an ARM "feature". Cortex-a8 fp comparison is very slow (> 20 cycles).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108256 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 1 deletions

diff --git a/lib/Target/ARM/ARM.td b/lib/Target/ARM/ARM.td
index f1e6a9f..fa64d6c 100644
--- a/lib/Target/ARM/ARM.td
+++ b/lib/Target/ARM/ARM.td
@@ -48,6 +48,8 @@ def FeatureHWDiv  : SubtargetFeature<"hwdiv", "HasHardwareDivide", "true",
                                      "Enable divide instructions">;
 def FeatureT2ExtractPack: SubtargetFeature<"t2xtpk", "HasT2ExtractPack", "true",
                                  "Enable Thumb2 extract and pack instructions">;
+def FeatureSlowFPBrcc : SubtargetFeature<"slow-fp-brcc", "SlowFPBrcc", "true",
+                                         "FP compare + branch is slow">;
 
 // Some processors have multiply-accumulate instructions that don't
 // play nicely with other VFP instructions, and it's generally better
@@ -129,7 +131,7 @@ def : Processor<"arm1156t2f-s",    ARMV6Itineraries,
 // V7 Processors.
 def : Processor<"cortex-a8",        CortexA8Itineraries,
                 [ArchV7A, FeatureThumb2, FeatureNEON, FeatureHasSlowVMLx,
-                 FeatureNEONForFP, FeatureT2ExtractPack]>;
+                 FeatureSlowFPBrcc, FeatureNEONForFP, FeatureT2ExtractPack]>;
 def : Processor<"cortex-a9",        CortexA9Itineraries,
                 [ArchV7A, FeatureThumb2, FeatureNEON, FeatureT2ExtractPack]>;
 def : ProcNoItin<"cortex-m3",       [ArchV7M, FeatureThumb2, FeatureHWDiv]>;
diff --git a/lib/Target/ARM/ARMSubtarget.h b/lib/Target/ARM/ARMSubtarget.h
index 8332bba..e7d92ed 100644
--- a/lib/Target/ARM/ARMSubtarget.h
+++ b/lib/Target/ARM/ARMSubtarget.h
@@ -54,6 +54,9 @@ protected:
   /// the VML[AS] instructions are slow (if so, don't use them).
   bool SlowVMLx;
 
+  /// SlowFPBrcc - True if floating point compare + branch is slow.
+  bool SlowFPBrcc;
+
   /// IsThumb - True if we are in thumb mode, false if in ARM mode.
   bool IsThumb;
 
@@ -133,6 +136,7 @@ protected:
   bool hasDivide() const { return HasHardwareDivide; }
   bool hasT2ExtractPack() const { return HasT2ExtractPack; }
   bool useVMLx() const {return hasVFP2() && !SlowVMLx; }
+  bool isFPBrccSlow() const { return SlowFPBrcc; }
 
   bool hasFP16() const { return HasFP16; }