[clang] [CLANG][CUDA] Enable nan/nanf from libdevice in device code (PR #158301)

[via cfe-commits]

https://github.com/DenisGZM created 
https://github.com/llvm/llvm-project/pull/158301

Added declarations for nan/nanf so Clang could translate it to appropriate 
functions from libdevice

>From 100645ecb2f8d406fb8c1b59c3e4f3e85ca81100 Mon Sep 17 00:00:00 2001
From: Denis Gerasimov <deng...@gmail.com>
Date: Fri, 12 Sep 2025 17:13:21 +0300
Subject: [PATCH] [CLANG][CUDA] Enable nan/nanf from libdevice in device code

---
 clang/lib/Headers/__clang_cuda_libdevice_declares.h | 4 ++--
 clang/lib/Headers/__clang_cuda_math.h               | 2 ++
 clang/test/Headers/Inputs/include/math.h            | 2 ++
 clang/test/Headers/nvptx_device_cmath_functions.cpp | 4 ++++
 clang/test/Headers/nvptx_device_math_functions.cpp  | 4 ++++
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Headers/__clang_cuda_libdevice_declares.h 
b/clang/lib/Headers/__clang_cuda_libdevice_declares.h
index ded0382a7ddce..cbc7f723ce8c4 100644
--- a/clang/lib/Headers/__clang_cuda_libdevice_declares.h
+++ b/clang/lib/Headers/__clang_cuda_libdevice_declares.h
@@ -269,8 +269,8 @@ __DEVICE__ float __nv_modff(float __a, float *__b);
 __DEVICE__ int __nv_mul24(int __a, int __b);
 __DEVICE__ long long __nv_mul64hi(long long __a, long long __b);
 __DEVICE__ int __nv_mulhi(int __a, int __b);
-__DEVICE__ double __nv_nan(const signed char *__a);
-__DEVICE__ float __nv_nanf(const signed char *__a);
+__DEVICE__ double __nv_nan(const char *__a);
+__DEVICE__ float __nv_nanf(const char *__a);
 __DEVICE__ double __nv_nearbyint(double __a);
 __DEVICE__ float __nv_nearbyintf(float __a);
 __DEVICE__ double __nv_nextafter(double __a, double __b);
diff --git a/clang/lib/Headers/__clang_cuda_math.h 
b/clang/lib/Headers/__clang_cuda_math.h
index 44c6e9a4e48d1..0d67ea309d272 100644
--- a/clang/lib/Headers/__clang_cuda_math.h
+++ b/clang/lib/Headers/__clang_cuda_math.h
@@ -201,6 +201,8 @@ __DEVICE__ int max(int __a, int __b) { return __nv_max(__a, 
__b); }
 __DEVICE__ int min(int __a, int __b) { return __nv_min(__a, __b); }
 __DEVICE__ double modf(double __a, double *__b) { return __nv_modf(__a, __b); }
 __DEVICE__ float modff(float __a, float *__b) { return __nv_modff(__a, __b); }
+__DEVICE__ float nanf(const char *__a) { return __nv_nanf(__a); }
+__DEVICE__ double nan(const char *__a) { return __nv_nan(__a); }
 __DEVICE__ double nearbyint(double __a) { return __builtin_nearbyint(__a); }
 __DEVICE__ float nearbyintf(float __a) { return __builtin_nearbyintf(__a); }
 __DEVICE__ double nextafter(double __a, double __b) {
diff --git a/clang/test/Headers/Inputs/include/math.h 
b/clang/test/Headers/Inputs/include/math.h
index cbd6bf7457a76..65f4395d6c966 100644
--- a/clang/test/Headers/Inputs/include/math.h
+++ b/clang/test/Headers/Inputs/include/math.h
@@ -107,6 +107,8 @@ long lround(double __a);
 long lroundf(float __a);
 double modf(double __a, double *__b);
 float modff(float __a, float *__b);
+float nanf(const char *__a);
+double nan(const char *__a);
 double nearbyint(double __a);
 float nearbyintf(float __a);
 double nextafter(double __a, double __b);
diff --git a/clang/test/Headers/nvptx_device_cmath_functions.cpp 
b/clang/test/Headers/nvptx_device_cmath_functions.cpp
index 898a8544a6e6a..04778210a2991 100644
--- a/clang/test/Headers/nvptx_device_cmath_functions.cpp
+++ b/clang/test/Headers/nvptx_device_cmath_functions.cpp
@@ -22,5 +22,9 @@ void test_sqrt(double a1) {
     double l4 = fabs(a1);
     // CHECK-YES: call noundef i32 @__nv_abs(i32
     double l5 = abs((int)a1);
+    // CHECK-YES: call noundef float @__nv_nanf(ptr noundef
+    float l6 = nanf("");
+    // CHECK-YES: call noundef double @__nv_nan(ptr noundef
+    double l7 = nan("");
   }
 }
diff --git a/clang/test/Headers/nvptx_device_math_functions.cpp 
b/clang/test/Headers/nvptx_device_math_functions.cpp
index 791cb49f918c7..d70f3d7dac582 100644
--- a/clang/test/Headers/nvptx_device_math_functions.cpp
+++ b/clang/test/Headers/nvptx_device_math_functions.cpp
@@ -22,5 +22,9 @@ void test_sqrt(double a1) {
     double l4 = fabs(a1);
     // CHECK-YES: call noundef i32 @__nv_abs(i32
     double l5 = abs((int)a1);
+    // CHECK-YES: call noundef float @__nv_nanf(ptr noundef
+    float l6 = nanf("");
+    // CHECK-YES: call noundef double @__nv_nan(ptr noundef
+    double l7 = nan("");
   }
 }

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