1 files changed, 86 insertions, 0 deletions
diff --git a/lib/std/special/compiler_rt/mulXf3_test.zig b/lib/std/special/compiler_rt/mulXf3_test.zig
new file mode 100644
index 0000000000..1c0c0fc043
--- /dev/null
+++ b/lib/std/special/compiler_rt/mulXf3_test.zig
@@ -0,0 +1,86 @@
+// Ported from:
+//
+// https://github.com/llvm/llvm-project/blob/2ffb1b0413efa9a24eb3c49e710e36f92e2cb50b/compiler-rt/test/builtins/Unit/multf3_test.c
+
+const qnan128 = @bitCast(f128, u128(0x7fff800000000000) << 64);
+const inf128 = @bitCast(f128, u128(0x7fff000000000000) << 64);
+
+const __multf3 = @import("mulXf3.zig").__multf3;
+
+// return true if equal
+// use two 64-bit integers intead of one 128-bit integer
+// because 128-bit integer constant can't be assigned directly
+fn compareResultLD(result: f128, expectedHi: u64, expectedLo: u64) bool {
+    const rep = @bitCast(u128, result);
+    const hi = @intCast(u64, rep >> 64);
+    const lo = @truncate(u64, rep);
+
+    if (hi == expectedHi and lo == expectedLo) {
+        return true;
+    }
+    // test other possible NaN representation(signal NaN)
+    if (expectedHi == 0x7fff800000000000 and expectedLo == 0x0) {
+        if ((hi & 0x7fff000000000000) == 0x7fff000000000000 and
+            ((hi & 0xffffffffffff) > 0 or lo > 0))
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+fn test__multf3(a: f128, b: f128, expected_hi: u64, expected_lo: u64) void {
+    const x = __multf3(a, b);
+
+    if (compareResultLD(x, expected_hi, expected_lo))
+        return;
+
+    @panic("__multf3 test failure");
+}
+
+fn makeNaN128(rand: u64) f128 {
+    const int_result = u128(0x7fff000000000000 | (rand & 0xffffffffffff)) << 64;
+    const float_result = @bitCast(f128, int_result);
+    return float_result;
+}
+test "multf3" {
+    // qNaN * any = qNaN
+    test__multf3(qnan128, 0x1.23456789abcdefp+5, 0x7fff800000000000, 0x0);
+
+    // NaN * any = NaN
+    const a = makeNaN128(0x800030000000);
+    test__multf3(a, 0x1.23456789abcdefp+5, 0x7fff800000000000, 0x0);
+    // inf * any = inf
+    test__multf3(inf128, 0x1.23456789abcdefp+5, 0x7fff000000000000, 0x0);
+
+    // any * any
+    test__multf3(
+        @bitCast(f128, u128(0x40042eab345678439abcdefea5678234)),
+        @bitCast(f128, u128(0x3ffeedcb34a235253948765432134675)),
+        0x400423e7f9e3c9fc,
+        0xd906c2c2a85777c4,
+    );
+
+    test__multf3(
+        @bitCast(f128, u128(0x3fcd353e45674d89abacc3a2ebf3ff50)),
+        @bitCast(f128, u128(0x3ff6ed8764648369535adf4be3214568)),
+        0x3fc52a163c6223fc,
+        0xc94c4bf0430768b4,
+    );
+
+    test__multf3(
+        0x1.234425696abcad34a35eeffefdcbap+456,
+        0x451.ed98d76e5d46e5f24323dff21ffp+600,
+        0x44293a91de5e0e94,
+        0xe8ed17cc2cdf64ac,
+    );
+
+    test__multf3(
+        @bitCast(f128, u128(0x3f154356473c82a9fabf2d22ace345df)),
+        @bitCast(f128, u128(0x3e38eda98765476743ab21da23d45679)),
+        0x3d4f37c1a3137cae,
+        0xfc6807048bc2836a,
+    );
+
+    test__multf3(0x1.23456734245345p-10000, 0x1.edcba524498724p-6497, 0x0, 0x0);
+}