diff options
Diffstat (limited to 'lib/builtins/i386/udivdi3.S')
| -rw-r--r-- | lib/builtins/i386/udivdi3.S | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/lib/builtins/i386/udivdi3.S b/lib/builtins/i386/udivdi3.S index 727613639..ca390245e 100644 --- a/lib/builtins/i386/udivdi3.S +++ b/lib/builtins/i386/udivdi3.S @@ -1,5 +1,6 @@ -// This file is dual licensed under the MIT and the University of Illinois Open -// Source Licenses. See LICENSE.TXT for details. +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception #include "../assembly.h" @@ -26,11 +27,11 @@ DEFINE_COMPILERRT_FUNCTION(__udivdi3) movl 20(%esp), %ebx // Find the index i of the leading bit in b. bsrl %ebx, %ecx // If the high word of b is zero, jump to jz 9f // the code to handle that special case [9]. - - /* High word of b is known to be non-zero on this branch */ - + + // High word of b is known to be non-zero on this branch + movl 16(%esp), %eax // Construct bhi, containing bits [1+i:32+i] of b - + shrl %cl, %eax // Practically, this means that bhi is given by: shrl %eax // notl %ecx // bhi = (high word of b) << (31 - i) | @@ -39,10 +40,10 @@ DEFINE_COMPILERRT_FUNCTION(__udivdi3) movl 12(%esp), %edx // Load the high and low words of a, and jump movl 8(%esp), %eax // to [1] if the high word is larger than bhi cmpl %ebx, %edx // to avoid overflowing the upcoming divide. - jae 1f - - /* High word of a is greater than or equal to (b >> (1 + i)) on this branch */ - + jae 1f + + // High word of a is greater than or equal to (b >> (1 + i)) on this branch + divl %ebx // eax <-- qs, edx <-- r such that ahi:alo = bs*qs + r pushl %edi @@ -66,8 +67,8 @@ DEFINE_COMPILERRT_FUNCTION(__udivdi3) retl -1: /* High word of a is greater than or equal to (b >> (1 + i)) on this branch */ - +1: // High word of a is greater than or equal to (b >> (1 + i)) on this branch + subl %ebx, %edx // subtract bhi from ahi so that divide will not divl %ebx // overflow, and find q and r such that // @@ -97,8 +98,8 @@ DEFINE_COMPILERRT_FUNCTION(__udivdi3) popl %ebx retl - -9: /* High word of b is zero on this branch */ + +9: // High word of b is zero on this branch movl 12(%esp), %eax // Find qhi and rhi such that movl 16(%esp), %ecx // |