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LLVM backend for 6502
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4d962b05ca
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Ahmed Bougacha 4d962b05ca [X86] Improve mul w/ overflow codegen, to MUL8+SETO. 
Currently, @llvm.smul.with.overflow.i8 expands to 9 instructions, where
3 are really needed.

This adds X86ISD::UMUL8/SMUL8 SD nodes, and custom lowers them to
MUL8/IMUL8 + SETO.

i8 is a special case because there is no two/three operand variants of
(I)MUL8, so the first operand and return value need to go in AL/AX.

Also, we can't write patterns for these instructions: TableGen refuses
patterns where output operands don't match SDNode results. In this case,
instructions where the output operand is an implicitly defined register.

A related special case (and FIXME) exists for MUL8 (X86InstrArith.td):

  // FIXME: Used for 8-bit mul, ignore result upper 8 bits.
  // This probably ought to be moved to a def : Pat<> if the
  // syntax can be accepted.
  [(set AL, (mul AL, GR8:$src)), (implicit EFLAGS)]

Ideally, these go away with UMUL8, but we still need to improve TableGen
support of implicit operands in patterns.

Before this change:
  movsbl  %sil, %eax
  movsbl  %dil, %ecx
  imull   %eax, %ecx
  movb    %cl, %al
  sarb    $7, %al
  movzbl  %al, %eax
  movzbl  %ch, %esi
  cmpl    %eax, %esi
  setne   %al

After:
  movb    %dil, %al
  imulb   %sil
  seto    %al

Also, remove a made-redundant testcase for PR19858, and enable more FastISel
ALU-overflow tests for SelectionDAG too.

Differential Revision: http://reviews.llvm.org/D5809


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220516 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-23 21:55:31 +00:00
autoconf Initial version of Go bindings. 2014-10-16 22:48:02 +00:00
bindings Add llvm-go tool. 2014-10-23 02:33:23 +00:00
cmake Add llvm-go tool. 2014-10-23 02:33:23 +00:00
docs Fix number of operands in documentation for minnum / maxnum 2014-10-22 18:25:02 +00:00
examples Add doInitialization/doFinalization to DataLayoutPass. 2014-09-10 21:27:43 +00:00
include Modernize doxygen comments in Support/Dwarf.h 2014-10-23 04:08:38 +00:00
lib [X86] Improve mul w/ overflow codegen, to MUL8+SETO. 2014-10-23 21:55:31 +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] Improve mul w/ overflow codegen, to MUL8+SETO. 2014-10-23 21:55:31 +00:00
tools Change the name of the field BindTable to bindtable to not over lap the type. 2014-10-23 19:53:12 +00:00
unittests Add unittest for extreme alignments. 2014-10-23 14:45:19 +00:00
utils [lit] Fix Python-3 compatibility, patch by Dan Liew. 2014-10-22 01:26:06 +00:00
.arcconfig Updated phabricator server. 2014-04-07 03:57:04 +00:00
.clang-format Test commit. 2014-03-02 13:08:46 +00:00
.clang-tidy Add .clang-tidy configuration file to provide LLVM-optimized defaults for 2014-09-08 13:30:00 +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 Initial version of Go bindings. 2014-10-16 22:48:02 +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 Remove the very substantial, largely unmaintained legacy PGO 2013-10-02 15:42:23 +00:00
Makefile [configure/make] Propagate names of build host tools when making BuildTools 2014-03-25 21:45:41 +00:00
Makefile.common Makefile.common: Update a description, s/Source/SOURCES/ , according to MakefileGuide.html#control-variables . 2012-12-07 01:43:23 +00:00
Makefile.config.in Initial version of Go bindings. 2014-10-16 22:48:02 +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

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