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author | Alexey Samsonov <samsonov@google.com> | 2014-02-14 09:20:33 +0000 |
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committer | Alexey Samsonov <samsonov@google.com> | 2014-02-14 09:20:33 +0000 |
commit | 53aa4fda49f94920139300227786ac47c393f1ce (patch) | |
tree | 6d022d04ee279fe1afd89668f346e28a9e3e1559 /lib/builtins/mulvti3.c | |
parent | 6d999e478fecb10dc43f20b85385d25cc239db0a (diff) | |
download | compiler-rt-53aa4fda49f94920139300227786ac47c393f1ce.tar.gz |
Move original compiler-rt functions (libgcc replacement) to lib/builtins directory
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@201393 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/builtins/mulvti3.c')
-rw-r--r-- | lib/builtins/mulvti3.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/lib/builtins/mulvti3.c b/lib/builtins/mulvti3.c new file mode 100644 index 000000000..31f7d2fd3 --- /dev/null +++ b/lib/builtins/mulvti3.c @@ -0,0 +1,60 @@ +/* ===-- mulvti3.c - Implement __mulvti3 -----------------------------------=== + * + * 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 __mulvti3 for the compiler_rt library. + * + * ===----------------------------------------------------------------------=== + */ + +#include "int_lib.h" + +#if __x86_64 + +/* Returns: a * b */ + +/* Effects: aborts if a * b overflows */ + +ti_int +__mulvti3(ti_int a, ti_int b) +{ + const int N = (int)(sizeof(ti_int) * CHAR_BIT); + const ti_int MIN = (ti_int)1 << (N-1); + const ti_int MAX = ~MIN; + if (a == MIN) + { + if (b == 0 || b == 1) + return a * b; + compilerrt_abort(); + } + if (b == MIN) + { + if (a == 0 || a == 1) + return a * b; + compilerrt_abort(); + } + ti_int sa = a >> (N - 1); + ti_int abs_a = (a ^ sa) - sa; + ti_int sb = b >> (N - 1); + ti_int abs_b = (b ^ sb) - sb; + if (abs_a < 2 || abs_b < 2) + return a * b; + if (sa == sb) + { + if (abs_a > MAX / abs_b) + compilerrt_abort(); + } + else + { + if (abs_a > MIN / -abs_b) + compilerrt_abort(); + } + return a * b; +} + +#endif |