[IR] Refactor attribute methods in Function class (NFC)

Rename the functions that query the optimization kind attributes.

Differential revision: https://reviews.llvm.org/D60287

llvm-svn: 357731
diff --git a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
index be9c1eb..37a85fa 100644
--- a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
+++ b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
@@ -1127,8 +1127,8 @@
   TII = static_cast<const Thumb2InstrInfo *>(STI->getInstrInfo());
 
   // Optimizing / minimizing size? Minimizing size implies optimizing for size.
-  OptimizeSize = MF.getFunction().optForSize();
-  MinimizeSize = STI->optForMinSize();
+  OptimizeSize = MF.getFunction().hasOptSize();
+  MinimizeSize = STI->hasMinSize();
 
   BlockInfo.clear();
   BlockInfo.resize(MF.getNumBlockIDs());