diff options
author | Jordan Rupprecht <rupprecht@google.com> | 2019-05-14 21:58:59 +0000 |
---|---|---|
committer | Jordan Rupprecht <rupprecht@google.com> | 2019-05-14 21:58:59 +0000 |
commit | b6bc976d7be8ee56d3be4b6dbd2f3ab0a4021c86 (patch) | |
tree | f5ed5db8cb5d237a073ea00c4d4cd63153a16a6c /lib/builtins/i386/moddi3.S | |
parent | 05342ccc9cff16425c0a831fddd510879544a0bf (diff) | |
parent | 098ca93185735ec3687106d0967a70fc99a85059 (diff) | |
download | compiler-rt-google/stable.tar.gz |
Creating branches/google/stable and tags/google/stable/2019-05-14 from r360103google/stable
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/branches/google/stable@360714 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/builtins/i386/moddi3.S')
-rw-r--r-- | lib/builtins/i386/moddi3.S | 41 |
1 files changed, 21 insertions, 20 deletions
diff --git a/lib/builtins/i386/moddi3.S b/lib/builtins/i386/moddi3.S index a5bf9ce8e..4580f20ea 100644 --- a/lib/builtins/i386/moddi3.S +++ b/lib/builtins/i386/moddi3.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" @@ -23,8 +24,8 @@ .balign 4 DEFINE_COMPILERRT_FUNCTION(__moddi3) -/* This is currently implemented by wrapping the unsigned modulus up in an absolute - value. This could certainly be improved upon. */ +// This is currently implemented by wrapping the unsigned modulus up in an absolute +// value. This could certainly be improved upon. pushl %esi movl 20(%esp), %edx // high word of b @@ -37,7 +38,7 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) sbbl %ecx, %edx // EDX:EAX = abs(b) movl %edx, 20(%esp) movl %eax, 16(%esp) // store abs(b) back to stack - + movl 12(%esp), %edx // high word of b movl 8(%esp), %eax // low word of b movl %edx, %ecx @@ -54,11 +55,11 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) movl 24(%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 20(%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) | @@ -67,10 +68,10 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) movl 16(%esp), %edx // Load the high and low words of a, and jump movl 12(%esp), %eax // to [2] if the high word is larger than bhi cmpl %ebx, %edx // to avoid overflowing the upcoming divide. - jae 2f - - /* High word of a is greater than or equal to (b >> (1 + i)) on this branch */ - + jae 2f + + // 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 @@ -86,13 +87,13 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) movl 28(%esp), %eax imull %edi, %eax // q*bhi subl %eax, %ecx // ECX:EBX = a - q*b - + jnc 1f // if positive, this is the result. addl 24(%esp), %ebx // otherwise adcl 28(%esp), %ecx // ECX:EBX = a - (q-1)*b = result 1: movl %ebx, %eax movl %ecx, %edx - + addl %esi, %eax // Restore correct sign to result adcl %esi, %edx xorl %esi, %eax @@ -102,8 +103,8 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) popl %esi retl // Return -2: /* High word of a is greater than or equal to (b >> (1 + i)) on this branch */ - +2: // 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 // @@ -132,7 +133,7 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) adcl 28(%esp), %ecx // ECX:EBX = a - (q-1)*b = result 3: movl %ebx, %eax movl %ecx, %edx - + addl %esi, %eax // Restore correct sign to result adcl %esi, %edx xorl %esi, %eax @@ -141,8 +142,8 @@ DEFINE_COMPILERRT_FUNCTION(__moddi3) popl %ebx popl %esi retl // Return - -9: /* High word of b is zero on this branch */ + +9: // High word of b is zero on this branch movl 16(%esp), %eax // Find qhi and rhi such that movl 20(%esp), %ecx // |