[PATCH] D113817: [X86] Promote f16 STRICT_FROUND to f32 and call libc.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, pengfei.
Herald added a subscriber: hiraditya.
craig.topper requested review of this revision.
Herald added a project: LLVM.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113817

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/fp-strict-scalar-round-fp16.ll


Index: llvm/test/CodeGen/X86/fp-strict-scalar-round-fp16.ll
===================================================================
--- llvm/test/CodeGen/X86/fp-strict-scalar-round-fp16.ll
+++ llvm/test/CodeGen/X86/fp-strict-scalar-round-fp16.ll
@@ -8,6 +8,7 @@
 declare half @llvm.experimental.constrained.rint.f16(half, metadata, metadata)
 declare half @llvm.experimental.constrained.nearbyint.f16(half, metadata, metadata)
 declare half @llvm.experimental.constrained.roundeven.f16(half, metadata)
+declare half @llvm.experimental.constrained.round.f16(half, metadata)
 
 define half @fceil32(half %f) #0 {
 ; X86-LABEL: fceil32:
@@ -102,4 +103,37 @@
   ret half %res
 }
 
+define half @fround16(half %f) #0 {
+; X86-LABEL: fround16:
+; X86:       # %bb.0:
+; X86-NEXT:    subl $8, %esp
+; X86-NEXT:    .cfi_def_cfa_offset 12
+; X86-NEXT:    vmovsh {{[0-9]+}}(%esp), %xmm0
+; X86-NEXT:    vcvtsh2ss %xmm0, %xmm0, %xmm0
+; X86-NEXT:    vmovss %xmm0, (%esp)
+; X86-NEXT:    calll roundf
+; X86-NEXT:    fstps {{[0-9]+}}(%esp)
+; X86-NEXT:    wait
+; X86-NEXT:    vmovss {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; X86-NEXT:    vcvtss2sh %xmm0, %xmm0, %xmm0
+; X86-NEXT:    addl $8, %esp
+; X86-NEXT:    .cfi_def_cfa_offset 4
+; X86-NEXT:    retl
+;
+; X64-LABEL: fround16:
+; X64:       # %bb.0:
+; X64-NEXT:    pushq %rax
+; X64-NEXT:    .cfi_def_cfa_offset 16
+; X64-NEXT:    vcvtsh2ss %xmm0, %xmm0, %xmm0
+; X64-NEXT:    callq roundf at PLT
+; X64-NEXT:    vcvtss2sh %xmm0, %xmm0, %xmm0
+; X64-NEXT:    popq %rax
+; X64-NEXT:    .cfi_def_cfa_offset 8
+; X64-NEXT:    retq
+
+  %res = call half @llvm.experimental.constrained.round.f16(
+                        half %f, metadata !"fpexcept.strict") #0
+  ret half %res
+}
+
 attributes #0 = { strictfp }
Index: llvm/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1961,7 +1961,7 @@
     setOperationAction(ISD::STRICT_FSETCC,        MVT::f16, Custom);
     setOperationAction(ISD::STRICT_FSETCCS,       MVT::f16, Custom);
     setOperationAction(ISD::FROUND,               MVT::f16, Custom);
-    setOperationAction(ISD::STRICT_FROUND,        MVT::f16, Custom);
+    setOperationAction(ISD::STRICT_FROUND,        MVT::f16, Promote);
     setOperationAction(ISD::FROUNDEVEN,           MVT::f16, Legal);
     setOperationAction(ISD::STRICT_FROUNDEVEN,    MVT::f16, Legal);
     setOperationAction(ISD::FP_ROUND,             MVT::f16, Custom);
@@ -22443,10 +22443,6 @@
 /// compiling with trapping math, we can emulate this with
 /// floor(X + copysign(nextafter(0.5, 0.0), X)).
 static SDValue LowerFROUND(SDValue Op, SelectionDAG &DAG) {
-  if (Op.getOpcode() == ISD::STRICT_FROUND &&
-      Op.getSimpleValueType() == MVT::f16)
-    report_fatal_error("For now cannot emit strict round(fp16) at backend for "
-                       "lacking library support.");
   SDValue N0 = Op.getOperand(0);
   SDLoc dl(Op);
   MVT VT = Op.getSimpleValueType();
@@ -31245,7 +31241,6 @@
   case ISD::STORE:              return LowerStore(Op, Subtarget, DAG);
   case ISD::FADD:
   case ISD::FSUB:               return lowerFaddFsub(Op, DAG);
-  case ISD::STRICT_FROUND:
   case ISD::FROUND:             return LowerFROUND(Op, DAG);
   case ISD::FABS:
   case ISD::FNEG:               return LowerFABSorFNEG(Op, DAG);
Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -4756,6 +4756,7 @@
     break;
   case ISD::STRICT_FFLOOR:
   case ISD::STRICT_FCEIL:
+  case ISD::STRICT_FROUND:
   case ISD::STRICT_FSIN:
   case ISD::STRICT_FCOS:
   case ISD::STRICT_FLOG:


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