From ed05086d61a6ef6c375d9d7e7e7f5a94b03a5b58 Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Thu, 17 Jul 2014 11:04:04 +0000
Subject: [PATCH] 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
---
 lib/Target/X86/X86ISelLowering.cpp |  4 ++++
 test/CodeGen/X86/cvt16.ll          | 16 +++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 39186c54f9d..d3d2c76de21 100644
--- 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 f3d80493210..501145ca715 100644
--- 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
-- 
2.34.1