[COMPILER-RT] Implement __floatsitf, __floatunstfsi

[koviankevin]

Summary

Implement floatsitf, floatunstfsi, which perform (signed/unsigned)integer to quad-precision conversion

[koviankevin]

add test

[koviankevin]

Use CRT_HAS_128BIT and modify the codes according to gribozavr's comments

[koviankevin]

introduce CRT_LDBL_128BIT

[koviankevin]

modify by gribozavr's comment and use COMPILER_RT_ABI

[joerg]

lib/builtins/floatsitf.c

32 ↗

(On Diff #7680)

Doesn't this produce a signed integer overlfow for INT_MIN? Same problem applies to the existing sources. What about moving the unsigned cast earlier by introducing an explicit aAbs variable?

test/builtins/Unit/floatunsitf_test.c

41 ↗

(On Diff #7680)

Can you use UINT64_C and drop the LP64 part?

[koviankevin]

use UINT64_C and drop le64

[joerg]

The INT_MIN case still doesn't look correct?

lib/builtins/floatsitf.c

30 ↗

(On Diff #9740)

unsigned aAbs = (unsigned)a;

33 ↗

(On Diff #9740)

aAbs += 0x8000000;

44 ↗

(On Diff #9740)

aAbs << shift

[koviankevin]

Adjusted as discussed

[joerg]

LGTM

[koviankevin]

This patch blocks quad math stuff on aarch64 from using compiler-rt instead of gnu libgcc
Can this patch be commited, now? Thanks

[joerg]

Closed by commit rL217901 (authored by @joerg).

compiler-rt/trunk/lib/builtins/floatsitf.c

+//===-- lib/floatsitf.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 integer 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 __floatsitf(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

compiler-rt/trunk/lib/builtins/floatunsitf.c

+//===-- lib/floatunsitf.c - uint -> 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 unsigned integer 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 __floatunsitf(unsigned int a) {
+
+    const int aWidth = sizeof a * CHAR_BIT;
+
+    // Handle zero as a special case to protect clz
+    if (a == 0) return fromRep(0);
+
+    // 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.
+    const int shift = significandBits - exponent;
+    result = (rep_t)a << shift ^ implicitBit;
+
+    // Insert the exponent
+    result += (rep_t)(exponent + exponentBias) << significandBits;
+    return fromRep(result);
+}
+
+#endif

compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c

+//===--------------- floatsitf_test.c - Test __floatsitf ------------------===//
+//
+//                     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 tests __floatsitf for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+
+#if __LDBL_MANT_DIG__ == 113
+
+#include "fp_test.h"
+
+long double __floatsitf(int a);
+
+int test__floatsitf(int a, uint64_t expectedHi, uint64_t expectedLo)
+{
+    long double x = __floatsitf(a);
+    int ret = compareResultLD(x, expectedHi, expectedLo);
+
+    if (ret)
+    {
+        printf("error in test__floatsitf(%d) = %.20Lf, "
+               "expected %.20Lf\n", a, x, fromRep128(expectedHi, expectedLo));
+    }
+    return ret;
+}
+
+char assumption_1[sizeof(long double) * CHAR_BIT == 128] = {0};
+
+#endif
+
+int main()
+{
+#if __LDBL_MANT_DIG__ == 113
+    if (test__floatsitf(0x7fffffff, UINT64_C(0x401dfffffffc0000), UINT64_C(0x0)))
+        return 1;
+    if (test__floatsitf(0, UINT64_C(0x0), UINT64_C(0x0)))
+        return 1;
+    if (test__floatsitf(0xffffffff, UINT64_C(0xbfff000000000000), UINT64_C(0x0)))
+        return 1;
+    if (test__floatsitf(0x12345678, UINT64_C(0x401b234567800000), UINT64_C(0x0)))
+        return 1;
+    if (test__floatsitf(-0x12345678, UINT64_C(0xc01b234567800000), UINT64_C(0x0)))
+        return 1;
+
+#else
+    printf("skipped\n");
+
+#endif
+    return 0;
+}

compiler-rt/trunk/test/builtins/Unit/floatunsitf_test.c

+//===--------------- floatunsitf_test.c - Test __floatunsitf --------------===//
+//
+//                     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 tests __floatunsitf for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+
+#if __LDBL_MANT_DIG__ == 113
+
+#include "fp_test.h"
+
+long double __floatunsitf(unsigned int a);
+
+int test__floatunsitf(unsigned int a, uint64_t expectedHi, uint64_t expectedLo)
+{
+    long double x = __floatunsitf(a);
+    int ret = compareResultLD(x, expectedHi, expectedLo);
+
+    if (ret){
+        printf("error in test__floatunsitf(%u) = %.20Lf, "
+               "expected %.20Lf\n", a, x, fromRep128(expectedHi, expectedLo));
+    }
+    return ret;
+}
+
+char assumption_1[sizeof(long double) * CHAR_BIT == 128] = {0};
+
+#endif
+
+int main()
+{
+#if __LDBL_MANT_DIG__ == 113
+    if (test__floatunsitf(0x7fffffff, UINT64_C(0x401dfffffffc0000), UINT64_C(0x0)))
+        return 1;
+    if (test__floatunsitf(0, UINT64_C(0x0), UINT64_C(0x0)))
+        return 1;
+    if (test__floatunsitf(0xffffffff, UINT64_C(0x401efffffffe0000), UINT64_C(0x0)))
+        return 1;
+    if (test__floatunsitf(0x12345678, UINT64_C(0x401b234567800000), UINT64_C(0x0)))
+        return 1;
+
+#else
+    printf("skipped\n");
+
+#endif
+    return 0;
+}