[llvm] r284086 - [AArch64][RegisterBankInfo] Provide more realistic copy costs.

[Quentin Colombet via llvm-commits]

Author: qcolombet
Date: Wed Oct 12 19:11:55 2016
New Revision: 284086

URL: http://llvm.org/viewvc/llvm-project?rev=284086&view=rev
Log:
[AArch64][RegisterBankInfo] Provide more realistic copy costs.

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64RegisterBankInfo.cpp

Modified: llvm/trunk/lib/Target/AArch64/AArch64RegisterBankInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64RegisterBankInfo.cpp?rev=284086&r1=284085&r2=284086&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64RegisterBankInfo.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64RegisterBankInfo.cpp Wed Oct 12 19:11:55 2016
@@ -181,7 +181,16 @@ unsigned AArch64RegisterBankInfo::copyCo
   // Will introduce other hooks for different size:
   // * extract cost.
   // * build_sequence cost.
-  // TODO: Add more accurate cost for FPR to/from GPR.
+
+  // Copy from (resp. to) GPR to (resp. from) FPR involves FMOV.
+  // FIXME: This should be deduced from the scheduling model.
+  if (&A == &AArch64::GPRRegBank && &B == &AArch64::FPRRegBank)
+    // FMOVXDr or FMOVWSr.
+    return 5;
+  if (&A == &AArch64::FPRRegBank && &B == &AArch64::GPRRegBank)
+    // FMOVDXr or FMOVSWr.
+    return 4;
+
   return RegisterBankInfo::copyCost(A, B, Size);
 }