Bugzilla Link	42711
Resolution	FIXED
Resolved on	Feb 27, 2020 02:48
Version	10.0
OS	Windows NT
Blocks	#41819 #43900
CC	@zmodem,@zygoloid,@sjoerdmeijer

Extended Description

Code to Reproduce(from ffmpeg):

#include <stdint.h>
#include <math.h>
#ifndef ff_ctzll
#define ff_ctzll(v) __builtin_ctzll(v)
#endif
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)

int64_t av_gcd(int64_t a, int64_t b) {
int za, zb, k;
int64_t u, v;
if (a == 0)
return b;
if (b == 0)
return a;
za = ff_ctzll(a);
zb = ff_ctzll(b);
k = FFMIN(za, zb);
u = llabs(a >> za);
v = llabs(b >> zb);
while (u != v) {
if (u > v)
FFSWAP(int64_t, v, u);
v -= u;
v >>= ff_ctzll(v);
}
return (uint64_t)u << k;
}

int main()
{
int v = av_gcd(123, 345);
}

Build Command:

gnu style: clang-9 -Oz -fuse-ld=lld-link-9 --target=i386-pc-windows-msvc -std=c11 -MD -Wl,-nodefaultlib:libcmt -Wl,-defaultlib:msvcrt clangcl32OzBug.c

vc style: clang-cl -Xclang -Oz --target=i386-pc-windows-msvc -MD clangcl32OzBug.c

Actual Results:

lld-link-9: error: undefined symbol: ___ashrdi3

referenced by /tmp/clangcl32OzBug-b06f63.o:(_av_gcd)
referenced by /tmp/clangcl32OzBug-b06f63.o:(_av_gcd)
referenced by /tmp/clangcl32OzBug-b06f63.o:(_av_gcd)

lld-link-9: error: undefined symbol: ___ashldi3

referenced by /tmp/clangcl32OzBug-b06f63.o:(_av_gcd)
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Expected Results:
no error

Additional Information:
x64 target, clang-8, -Os -O2 no error.
__ashrdi3 exists in libgcc and compiler-rt.