compiler-rt: add floatditf and floatunditf

These are long integer (di_int/du_int) to quad precision floating point
conversions. They may be reworked based on upstream discussion. These
versions are here to support arm64 world builds.

Reviewed by:	ed
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D2174

1 files changed, 52 insertions, 0 deletions

diff --git a/contrib/compiler-rt/lib/builtins/floatditf.c b/contrib/compiler-rt/lib/builtins/floatditf.c
new file mode 100644
index 0000000..01261c6
--- /dev/null
+++ b/contrib/compiler-rt/lib/builtins/floatditf.c
@@ -0,0 +1,52 @@
+//===-- lib/floatditf.c - integer -> quad-precision conversion ----*- C -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements di_int to quad-precision conversion for the
+// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
+// mode.
+//
+//===----------------------------------------------------------------------===//
+
+#define QUAD_PRECISION
+#include "fp_lib.h"
+
+#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
+COMPILER_RT_ABI fp_t __floatditf(di_int a) {
+
+    const int aWidth = sizeof a * CHAR_BIT;
+
+    // Handle zero as a special case to protect clz
+    if (a == 0)
+        return fromRep(0);
+
+    // All other cases begin by extracting the sign and absolute value of a
+    rep_t sign = 0;
+    unsigned aAbs = (unsigned)a;
+    if (a < 0) {
+        sign = signBit;
+        aAbs += 0x80000000;
+    }
+
+    // Exponent of (fp_t)a is the width of abs(a).
+    const int exponent = (aWidth - 1) - __builtin_clz(a);
+    rep_t result;
+
+    // Shift a into the significand field and clear the implicit bit.  Extra
+    // cast to unsigned int is necessary to get the correct behavior for
+    // the input INT_MIN.
+    const int shift = significandBits - exponent;
+    result = (rep_t)aAbs << shift ^ implicitBit;
+
+    // Insert the exponent
+    result += (rep_t)(exponent + exponentBias) << significandBits;
+    // Insert the sign bit and return
+    return fromRep(result | sign);
+}
+
+#endif