LLVM backend for 6502
Go to file
Chris Lattner 8d2822e7f1 Use the fucomi[p] instructions to perform floating point comparisons instead
of the fucom[p][p] instructions.  This allows us to code generate this function

bool %test(double %X, double %Y) {
        %C = setlt double %Y, %X
        ret bool %C
}

... into:

test:
        fld QWORD PTR [%ESP + 4]
        fld QWORD PTR [%ESP + 12]
        fucomip %ST(1)
        fstp %ST(0)
        setb %AL
        movsx %EAX, %AL
        ret

where before we generated:

test:
        fld QWORD PTR [%ESP + 4]
        fld QWORD PTR [%ESP + 12]
        fucompp
**      fnstsw
**      sahf
        setb %AL
        movsx %EAX, %AL
        ret

The two marked instructions (which are the ones eliminated) are very bad,
because they serialize execution of the processor.  These instructions are
available on the PPRO and later, but since we already use cmov's we aren't
losing any portability.

I retained the old code for the day when we decide we want to support back
to the 386.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12852 91177308-0d34-0410-b5e6-96231b3b80d8
2004-04-12 01:43:36 +00:00
autoconf check for isatty function 2004-04-02 21:06:44 +00:00
docs Add note 2004-04-10 06:56:53 +00:00
examples/ModuleMaker Configure script for ModuleMaker. 2003-11-25 20:02:07 +00:00
include Make comments above APIs reflect what they should do. 2004-04-11 16:42:50 +00:00
lib Use the fucomi[p] instructions to perform floating point comparisons instead 2004-04-12 01:43:36 +00:00
projects Avoid TRUE and FALSE which apparently conflict with some macros on OSX 2004-03-31 03:49:47 +00:00
runtime Merged in RELEASE_12. 2004-03-29 20:22:30 +00:00
test New testcase 2004-04-11 23:18:30 +00:00
tools Disambiguate symbols after loop extraction so that we can diagnose a code 2004-04-11 23:52:35 +00:00
utils Tablegen backend for really simple instruction selector 2004-04-06 19:31:31 +00:00
.cvsignore
configure Regenerated using autoconf-2.57. 2004-04-02 21:26:02 +00:00
CREDITS.TXT Added Stacker to Reid Spencer's list of contributions. 2003-12-17 18:15:04 +00:00
LICENSE.TXT Adding kimwitu++ license. 2004-04-06 20:23:45 +00:00
llvm.spec RPM spec file for LLVM tools and libraries. 2004-02-10 03:57:51 +00:00
llvm.spec.in RPM spec file for LLVM tools and libraries. 2004-02-10 03:57:51 +00:00
Makefile Should fix pr220 - "make install" doesn't install header files when 2004-02-10 01:10:01 +00:00
Makefile.common
Makefile.config.in Fix up a seriously outdated comment. 2004-03-10 17:37:50 +00:00
Makefile.rules Add support for 'install-bytecode' target, used for ONLY installing 2004-03-10 17:38:01 +00:00
README.txt Merged in RELEASE_1. 2003-10-27 18:02:06 +00:00

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