X86: support double extension of f16 type.

x86 has no native ability to extend an f16 to f64, but the same result
is obtained if we expand it into two separate extensions: f16 -> f32
-> f64.

Unfortunately the same is not true for truncate, so that still results
in a compilation failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213251 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 39186c54f9d48c8e4aacbdfaab50465141082f52..d3d2c76de215ae4385d532c64d35b40e272bc109 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -523,6 +523,10 @@ void X86TargetLowering::resetOperationActions() {
     setOperationAction(ISD::FP_TO_FP16, MVT::f32, Expand);
   }
 
+  // There's never any support for extending beyond MVT::f32.
+  setOperationAction(ISD::FP16_TO_FP, MVT::f64, Expand);
+  setOperationAction(ISD::FP16_TO_FP, MVT::f80, Expand);
+
   if (Subtarget->hasPOPCNT()) {
     setOperationAction(ISD::CTPOP          , MVT::i8   , Promote);
   } else {

diff --git a/test/CodeGen/X86/cvt16.ll b/test/CodeGen/X86/cvt16.ll
index f3d8049321007cdeba1043071206f5d944af60c2..501145ca7151000544aae48d0219f1d20cf325e7 100644 (file)
--- a/test/CodeGen/X86/cvt16.ll
+++ b/test/CodeGen/X86/cvt16.ll
@@ -59,6 +59,20 @@ define float @test3(float %src) nounwind uwtable readnone {
 ; F16C-NEXT: vcvtph2ps
 ; F16C: ret
 
+define double @test4(i16* nocapture %src) {
+  %1 = load i16* %src, align 2
+  %2 = tail call double @llvm.convert.from.fp16.f64(i16 %1)
+  ret double %2
+}
+; CHECK-LABEL: test4:
+; LIBCALL: callq  __gnu_h2f_ieee
+; LIBCALL: cvtss2sd
+; SOFTFLOAT: callq  __gnu_h2f_ieee
+; SOFTFLOAT: callq __extendsfdf2
+; F16C: vcvtph2ps
+; F16C: vcvtss2sd
+; F16C: ret
+
 declare float @llvm.convert.from.fp16.f32(i16) nounwind readnone
 declare i16 @llvm.convert.to.fp16.f32(float) nounwind readnone
-
+declare double @llvm.convert.from.fp16.f64(i16) nounwind readnone