Add frintp instruction.

src/arm64/simulator-arm64.cc

Index: src/arm64/simulator-arm64.cc
diff --git a/src/arm64/simulator-arm64.cc b/src/arm64/simulator-arm64.cc
index 129252b49b45cf8c3d726287d82b0fdaf95393e0..569be9cc83420dbd7ae72fdf6c31fb8982b4c2ca 100644
--- a/src/arm64/simulator-arm64.cc
+++ b/src/arm64/simulator-arm64.cc
@@ -2463,6 +2463,12 @@ void Simulator::VisitFPDataProcessing1Source(Instruction* instr) {
         set_sreg(fd, FPRoundInt(sreg(fn), FPNegativeInfinity)); break;
     case FRINTM_d:
         set_dreg(fd, FPRoundInt(dreg(fn), FPNegativeInfinity)); break;
+    case FRINTP_s:
+      set_sreg(fd, FPRoundInt(sreg(fn), FPPositiveInfinity));
+      break;
+    case FRINTP_d:
+      set_dreg(fd, FPRoundInt(dreg(fn), FPPositiveInfinity));
+      break;
     case FRINTN_s: set_sreg(fd, FPRoundInt(sreg(fn), FPTieEven)); break;
     case FRINTN_d: set_dreg(fd, FPRoundInt(dreg(fn), FPTieEven)); break;
     case FRINTZ_s: set_sreg(fd, FPRoundInt(sreg(fn), FPZero)); break;
@@ -2767,6 +2773,10 @@ double Simulator::FPRoundInt(double value, FPRounding round_mode) {
       // We always use floor(value).
       break;
     }
+    case FPPositiveInfinity: {
+      int_result = ceil(value);

[Rodolph Perfetta (ARM), 2014/10/21 19:22:00]

Is ceil of a value in the range ]-1, -0] guaranteed to return -0 on all
supported platform?

[Sven Panne, 2014/10/22 06:34:40]

According to http://stackoverflow.com/questions/5986875/c-ceil-and-negative-zero
it should, but I fail to find the quoted part of the C standard in my local
copy. :-/

[sigurds, 2014/10/22 09:53:30]

F.9.6.1 of the standard defines ceil(). Annex F begins with stating that 
"An implementation that defines __STDC_IEC_559__ shall conform to the
specifications in this annex. Where a binding between the C language and IEC
60559 is indicated, the IEC 60559-specified behavior is adopted by reference,
unless stated otherwise."

I interpret this to mean: Every implementation defining __STDC_IEC_559__
implements IEEE behavior for ceil.

As Sven pointed out in personal discussion, if ceil would not conform to IEEE,
then we'd have problem in the implementation of DoubleToInteger in
conversions-inl.h:78, where we assume IEEE behavior.

+      break;
+    }
     default: UNIMPLEMENTED();
   }
   return int_result;