From fd089990f76ec6392dbd0138ab874d90c632d2a4 Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Fri, 26 Jun 2009 16:47:03 +0000
Subject: Initial import of compiler-rt.  -

llvm-svn: 74292
---
 compiler-rt/lib/mulvdi3.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 compiler-rt/lib/mulvdi3.c

(limited to 'compiler-rt/lib/mulvdi3.c')

diff --git a/compiler-rt/lib/mulvdi3.c b/compiler-rt/lib/mulvdi3.c
new file mode 100644
index 00000000000..862a8c0063d
--- /dev/null
+++ b/compiler-rt/lib/mulvdi3.c
@@ -0,0 +1,56 @@
+//===-- mulvdi3.c - Implement __mulvdi3 -----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __mulvdi3 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+#include <stdlib.h>
+
+// Returns: a * b
+
+// Effects: aborts if a * b overflows
+
+di_int
+__mulvdi3(di_int a, di_int b)
+{
+    const int N = (int)(sizeof(di_int) * CHAR_BIT);
+    const di_int MIN = (di_int)1 << (N-1);
+    const di_int MAX = ~MIN;
+    if (a == MIN)
+    {
+        if (b == 0 || b == 1)
+            return a * b;
+        abort();
+    }
+    if (b == MIN)
+    {
+        if (a == 0 || a == 1)
+            return a * b;
+        abort();
+    }
+    di_int sa = a >> (N - 1);
+    di_int abs_a = (a ^ sa) - sa;
+    di_int sb = b >> (N - 1);
+    di_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)
+            abort();
+    }
+    else
+    {
+        if (abs_a > MIN / -abs_b)
+            abort();
+    }
+    return a * b;
+}
-- 
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