[PATCH] D54583: PowerPC: Optimize SPE double parameter calling setup

[Kei Thomsen via Phabricator via llvm-commits]

kthomsen added a comment.

I found an issue with the SPE compare operations. The result of a efdcmpeq , efdcmpgt and efdcmplt is every time the GT-Bit in the Condition Register. This is adressed in one place of the PPCISelDAGToDAG.cpp, but not addressed for a second case of the code generation.
The diff of PPCISelDAGToDAG.cpp is:

  --- PPCISelDAGToDAG.cpp 2019-03-12 15:35:45.000000000 +0100
  +++ "\\ellcc\\PPCISelDAGToDAG.cpp"      2019-03-27 10:52:21.088326000 +0100
  @@ -5039,6 +5038,32 @@ void PPCDAGToDAGISel::Select(SDNode *N)
         PCC |= getBranchHint(PCC, FuncInfo, N->getOperand(4));
  
       SDValue CondCode = SelectCC(N->getOperand(2), N->getOperand(3), CC, dl);
  +
  +    if (PPCSubTarget->hasSPE() && N->getOperand(2).getValueType().isFloatingPoint()) {
  +      // For SPE instructions, the result is in GT bit of the CR
  +      switch(CC) {
  +        case ISD::SETOEQ:
  +        case ISD::SETEQ:
  +        case ISD::SETOLT:
  +        case ISD::SETLT:
  +        case ISD::SETOGT:
  +        case ISD::SETGT:
  +                PCC = PPC::PRED_GT;
  +                break;
  +        case ISD::SETUNE:
  +        case ISD::SETNE:
  +        case ISD::SETULE:
  +        case ISD::SETLE:
  +        case ISD::SETUGE:
  +        case ISD::SETGE:
  +                PCC = PPC::PRED_LE;
  +                break;
  +        default:
  +                break;
  +      }
  +    }
  +
  +
       SDValue Ops[] = { getI32Imm(PCC, dl), CondCode,
                           N->getOperand(4), N->getOperand(0) };
       CurDAG->SelectNodeTo(N, PPC::BCC, MVT::Other, Ops);

The following testprogram is checking all methods. And the LIBC++ tests are now correctly compiled and running (about 1000 of 5800 failed before).

  #include <stdio.h>
  
  int teq(double a, double b)
  {
      printf("%lf == %lf\n",a,b);
      if (a == b)
      {
        printf("equal\n");
        return 1;
      }
      printf("!equal\n");
      return 0;
  }
  
  int tne(double a, double b)
  {
      printf("%lf != %lf\n",a,b);
      if (a != b)
      {
        printf("notequal\n");
        return 1;
      }
      printf("!notequal\n");
      return 0;
  }
  int tgt(double a, double b)
  {
      printf("%lf > %lf\n",a,b);
      if (a > b)
      {
        printf("greater than\n");
        return 1;
      }
      printf("!greater than\n");
      return 0;
  }
  int tge(double a, double b)
  {
      printf("%lf >= %lf\n",a,b);
      if (a >= b)
      {
        printf("greater equal\n");
        return 1;
      }
      printf("!greater equal\n");
      return 0;
  }
  int tlt(double a, double b)
  {
      printf("%lf < %lf\n",a,b);
      if (a < b)
      {
        printf("less than\n");
        return 1;
      }
      printf("!less than\n");
      return 0;
  }
  
  int tle(double a, double b)
  {
      printf("%lf <= %lf\n",a,b);
      if (a <= b)
      {
        printf("less equal\n");
        return 1;
      }
      printf("!less equal\n");
      return 0;
  }
  
  int main()
  {
      teq(5.5,5.5);
      teq(5.5,5.6);
          
      tne(5.5,5.6);
      tne(5.5,5.5);
      
      tgt(5.5,5.6);
      tgt(5.5,5.5);
      tgt(5.5,5.4);
      
      tge(5.5,5.6);
      tge(5.5,5.5);
      tge(5.5,5.4);
      
      tlt(5.5,5.6);
      tlt(5.5,5.5);
      tlt(5.5,5.4);
      
      tle(5.5,5.6);
      tle(5.5,5.5);
      tle(5.5,5.4);
          
      return 0;
  }

The result is:

  $ eq
  5.500000 == 5.500000
  equal
  5.500000 == 5.600000
  !equal
  5.500000 != 5.600000
  notequal
  5.500000 != 5.500000
  !notequal
  5.500000 > 5.600000
  !greater than
  5.500000 > 5.500000
  !greater than
  5.500000 > 5.400000
  greater than
  5.500000 >= 5.600000
  !greater equal
  5.500000 >= 5.500000
  greater equal
  5.500000 >= 5.400000
  greater equal
  5.500000 < 5.600000
  less than
  5.500000 < 5.500000
  !less than
  5.500000 < 5.400000
  !less than
  5.500000 <= 5.600000
  less equal
  5.500000 <= 5.500000
  less equal
  5.500000 <= 5.400000
  !less equal

I'm not sure if this fix is good for D54583 <https://reviews.llvm.org/D54583> or if you like to create a new one.

Best regards, Kei


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  https://reviews.llvm.org/D54583/new/

https://reviews.llvm.org/D54583