https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114907
Bug ID: 114907
Summary: Missing __extendhfbf2 in libgcc
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgcc
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: crazylht at gmail dot com
Target Milestone: ---
Target: x86-64
>From https://sourceware.org/bugzilla/show_bug.cgi?id=31685
$ cat x.cc
#include <stdlib.h>
#include <cstdint>
#include <array>
#include <iostream>
#define SIZE 8
typedef _Float16 T;
//typedef volatile float T;
void fp16tobf16(_Float16 * f) {
__bf16 * b = reinterpret_cast<__bf16*>(f);
for(int i=0; i<SIZE; i++){
T temp = f[i];
b[i] = (__bf16) temp;
}
}
int main(){
std::array<_Float16, SIZE> a{};
std::fill(a.begin(), a.end(), (_Float16) 1.7653432432424324);
fp16tobf16(a.data());
__bf16 * b = reinterpret_cast<__bf16*>(a.data());
std::cout << "\n";
for(int i=0; i<SIZE; i++)
std::cout << ((double) b[i]) << "\n";
return 0;
}
$ g++ -O0 -std=c++23 x.cc
/usr/local/bin/ld: /tmp/ccWrIm0Z.o: in function `fp16tobf16(_Float16*)':
x.cc:(.text+0x4d): undefined reference to `__extendhfbf2'
collect2: error: ld returned 1 exit status
$
