[llvm] r292452 - [NVPTX] Fix lowering of fp16 ISD::FNEG.

[Artem Belevich via llvm-commits]

Author: tra
Date: Wed Jan 18 18:14:45 2017
New Revision: 292452

URL: http://llvm.org/viewvc/llvm-project?rev=292452&view=rev
Log:
[NVPTX] Fix lowering of fp16 ISD::FNEG.

There's no neg.f16 instruction, so negation has to
be done via subtraction from zero.

Differential Revision: https://reviews.llvm.org/D28876

Modified:
    llvm/trunk/lib/Target/NVPTX/NVPTXISelLowering.cpp
    llvm/trunk/test/CodeGen/NVPTX/f16-instructions.ll

Modified: llvm/trunk/lib/Target/NVPTX/NVPTXISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVPTXISelLowering.cpp?rev=292452&r1=292451&r2=292452&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVPTXISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/NVPTX/NVPTXISelLowering.cpp Wed Jan 18 18:14:45 2017
@@ -332,6 +332,8 @@ NVPTXTargetLowering::NVPTXTargetLowering
     setOperationAction(ISD::FSUB, MVT::f16, Promote);
     setOperationAction(ISD::FMA, MVT::f16, Promote);
   }
+  // There's no neg.f16 instruction.
+  setOperationAction(ISD::FNEG, MVT::f16, Expand);
 
   // Library functions.  These default to Expand, but we have instructions
   // for them.

Modified: llvm/trunk/test/CodeGen/NVPTX/f16-instructions.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/NVPTX/f16-instructions.ll?rev=292452&r1=292451&r2=292452&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/NVPTX/f16-instructions.ll (original)
+++ llvm/trunk/test/CodeGen/NVPTX/f16-instructions.ll Wed Jan 18 18:14:45 2017
@@ -80,6 +80,21 @@ define half @test_fsub(half %a, half %b)
   ret half %r
 }
 
+; CHECK-LABEL: test_fneg(
+; CHECK-DAG:  ld.param.b16    [[A:%h[0-9]+]], [test_fneg_param_0];
+; CHECK-F16-NEXT:   mov.b16        [[Z:%h[0-9]+]], 0x0000
+; CHECK-F16-NEXT:   sub.rn.f16     [[R:%h[0-9]+]], [[Z]], [[A]];
+; CHECK-NOF16-DAG:  cvt.f32.f16    [[A32:%f[0-9]+]], [[A]]
+; CHECK-NOF16-DAG:  mov.f32        [[Z:%f[0-9]+]], 0f00000000;
+; CHECK-NOF16-NEXT: sub.rn.f32     [[R32:%f[0-9]+]], [[Z]], [[A32]];
+; CHECK-NOF16-NEXT: cvt.rn.f16.f32 [[R:%h[0-9]+]], [[R32]]
+; CHECK-NEXT: st.param.b16    [func_retval0+0], [[R]];
+; CHECK-NEXT: ret;
+define half @test_fneg(half %a) #0 {
+  %r = fsub half 0.0, %a
+  ret half %r
+}
+
 ; CHECK-LABEL: test_fmul(
 ; CHECK-DAG:  ld.param.b16    [[A:%h[0-9]+]], [test_fmul_param_0];
 ; CHECK-DAG:  ld.param.b16    [[B:%h[0-9]+]], [test_fmul_param_1];