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LLVM backend for 6502
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40453da779
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Ahmed Bougacha 40453da779 [X86] 8bit divrem: Improve codegen for AH register extraction. 
For 8-bit divrems where the remainder is used, we used to generate:
    divb  %sil
    shrw  $8, %ax
    movzbl  %al, %eax

That was to avoid an H-reg access, which is problematic mainly because
it isn't possible in REX-prefixed instructions.

This patch optimizes that to:
    divb  %sil
    movzbl  %ah, %eax

To do that, we explicitly extend AH, and extract the L-subreg in the
resulting register.  The extension is done using the NOREX variants of
MOVZX.  To support signed operations, MOVSX_NOREX is also added.
Further, this introduces a new SDNode type, [us]divrem_ext_hreg, which is
then lowered to a sequence containing a single zext (rather than 2).

Differential Revision: http://reviews.llvm.org/D6064


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221176 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-03 20:26:35 +00:00
autoconf [OCaml] [autoconf] Migrate to ocamlfind. 2014-10-30 08:29:45 +00:00
bindings [OCaml] Fix mismatched CAMLparam/CAMLreturn. 2014-11-03 11:47:14 +00:00
cmake [cmake] Pass -O3 when linking. 2014-11-02 12:14:22 +00:00
docs Docs: update va_arg example with valid x86_64 va_list type. 2014-11-02 01:21:51 +00:00
examples [CMake] llvm/examples: Update libdeps for unoptimized builds. 2014-10-31 15:27:16 +00:00
include Relax the LLVM_NOEXCEPT _MSC_VER version check back to 1900 2014-11-03 18:22:42 +00:00
lib [X86] 8bit divrem: Improve codegen for AH register extraction. 2014-11-03 20:26:35 +00:00
projects [cmake] Use the external project machinery for libcxxabi so that it can 2014-07-25 10:27:40 +00:00
test [X86] 8bit divrem: Improve codegen for AH register extraction. 2014-11-03 20:26:35 +00:00
tools llvm-vtabledump: Handle Itanium VTables 2014-11-03 07:23:25 +00:00
unittests Remove the PreserveSource linker mode. 2014-10-28 00:24:16 +00:00
utils Support REG_SEQUENCE in tablegen. 2014-11-02 23:46:51 +00:00
.arcconfig Updated phabricator server. 2014-04-07 03:57:04 +00:00
.clang-format
.clang-tidy Enable display of compiler diagnostics in clang-tidy by default. 2014-10-29 17:29:38 +00:00
.gitignore Initial version of Go bindings. 2014-10-16 22:48:02 +00:00
CMakeLists.txt Adding llvm-shlib to CMake build system with a few new bells and whistles 2014-10-23 17:22:14 +00:00
CODE_OWNERS.TXT Add Tom Stellard's role as 3.5 release manager. 2014-09-12 08:07:31 +00:00
configure [OCaml] [autoconf] Migrate to ocamlfind. 2014-10-30 08:29:45 +00:00
CREDITS.TXT Rise from the dead and update personal info 2014-08-25 17:51:04 +00:00
LICENSE.TXT Remove projects/sample. 2014-03-12 22:40:22 +00:00
llvm.spec.in
LLVMBuild.txt
Makefile [configure/make] Propagate names of build host tools when making BuildTools 2014-03-25 21:45:41 +00:00
Makefile.common
Makefile.config.in [OCaml] [autoconf] Migrate to ocamlfind. 2014-10-30 08:29:45 +00:00
Makefile.rules Revert my earlier change to add "all" as a dependency to check. In 2014-09-19 18:44:27 +00:00
README.txt Trivial test commit. 2014-04-26 19:05:45 +00:00

README.txt 

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