[libclc] libclc: generic: add half implementation for erf/erfc (PR #66901)

[Romaric Jodin via cfe-commits]

https://github.com/rjodinchr created https://github.com/llvm/llvm-project/pull/66901

libclc does not have a half implementation for erf/erfc
Add one based on the float implementation by extending the input and truncating the output.

>From 64826c23cfaef764c9a60600a2c0e96244c95cf6 Mon Sep 17 00:00:00 2001
From: Romaric Jodin <rjodin at chromium.org>
Date: Mon, 21 Aug 2023 10:55:44 +0200
Subject: [PATCH] libclc: generic: add half implementation for erf/erfc

libclc does not have a half implementation for erf/erfc
Add one based on the float implementation by extending the input and
truncating the output.
---
 libclc/generic/lib/math/erf.cl  | 12 ++++++++++++
 libclc/generic/lib/math/erfc.cl | 12 ++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/libclc/generic/lib/math/erf.cl b/libclc/generic/lib/math/erf.cl
index 3dc82d926e863a6..2c395ce1a75267b 100644
--- a/libclc/generic/lib/math/erf.cl
+++ b/libclc/generic/lib/math/erf.cl
@@ -399,4 +399,16 @@ _CLC_OVERLOAD _CLC_DEF double erf(double y) {
 
 _CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, erf, double);
 
+#ifdef cl_khr_fp16
+
+#pragma OPENCL EXTENSION cl_khr_fp16 : enable
+
+_CLC_OVERLOAD _CLC_DEF half erf(half h) {
+    return (half)erf((float)h);
+}
+
+_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, half, erf, half);
+
+#endif
+
 #endif
diff --git a/libclc/generic/lib/math/erfc.cl b/libclc/generic/lib/math/erfc.cl
index c322f8691b3828a..cd35ea8def7b6a8 100644
--- a/libclc/generic/lib/math/erfc.cl
+++ b/libclc/generic/lib/math/erfc.cl
@@ -410,4 +410,16 @@ _CLC_OVERLOAD _CLC_DEF double erfc(double x) {
 
 _CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, erfc, double);
 
+#ifdef cl_khr_fp16
+
+#pragma OPENCL EXTENSION cl_khr_fp16 : enable
+
+_CLC_OVERLOAD _CLC_DEF half erfc(half h) {
+    return (half)erfc((float)h);
+}
+
+_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, half, erfc, half);
+
+#endif
+
 #endif