forked from OSchip/llvm-project
de87d146ab
typically cost 1 cycle) instead of shld/shrd instruction (which are typically
6 or more cycles). This also saves code space.
For example, instead of emitting:
rotr:
mov %EAX, DWORD PTR [%ESP + 4]
mov %CL, BYTE PTR [%ESP + 8]
shrd %EAX, %EAX, %CL
ret
rotli:
mov %EAX, DWORD PTR [%ESP + 4]
shrd %EAX, %EAX, 27
ret
Emit:
rotr32:
mov %CL, BYTE PTR [%ESP + 8]
mov %EAX, DWORD PTR [%ESP + 4]
ror %EAX, %CL
ret
rotli32:
mov %EAX, DWORD PTR [%ESP + 4]
ror %EAX, 27
ret
We also emit byte rotate instructions which do not have a sh[lr]d counterpart
at all.
llvm-svn: 19692
|
||
|---|---|---|
| .. | ||
| autoconf | ||
| docs | ||
| examples | ||
| include/llvm | ||
| lib | ||
| projects | ||
| runtime | ||
| test | ||
| tools | ||
| utils | ||
| win32 | ||
| .cvsignore | ||
| CREDITS.TXT | ||
| LICENSE.TXT | ||
| Makefile | ||
| Makefile.common | ||
| Makefile.config.in | ||
| Makefile.rules | ||
| README.txt | ||
| configure | ||
| llvm.spec | ||
README.txt
Low Level Virtual Machine (LLVM) ================================ This directory and its subdirectories contain source code for the Low Level Virtual Machine, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. Please see the HTML documentation provided in docs/index.html for further assistance with LLVM.