subtracts. This is a very rough and nasty implementation of Lefevre's
"pattern finding" algorithm. With a few small changes though, it should
end up beating most other methods in common use, regardless of the size
of the constant (currently, it's often one or two shifts worse)
TODO: rewrite it so it's not hideously ugly (this is a translation from
perl, which doesn't help ;)
bypass most of it for multiplies by 2^n+1
(eventually) teach it that some combinations of shift+add are
cheaper than others (e.g. shladd on ia64, scaled adds on alpha)
get it to try multiple booth encodings in search of the cheapest
routine
make it work for negative constants
This is hacked up as a DAG->DAG transform, so once I clean it up I hope
it'll be pulled out of here and put somewhere else. The only thing backends
should really have to worry about for now is where to draw the line
between using this code vs. going ahead and doing an integer multiply
anyway.
llvm-svn: 21560
variable TARGETS_TO_BUILD is used to determine which targets in lib/Target
are built and which libraries are linked into llc. This effectively
implements the feature. One item remains: disabling targets in the dejagnu
test suite.
llvm-svn: 21450
printf format strings and other stuff. Instead of generating this:
movl $l1__2E_str_1, %eax
movl %eax, (%esp)
we now emit:
movl $l1__2E_str_1, (%esp)
llvm-svn: 21406
register. Added support in the .td file for the g5-specific variant
of cr -> gpr moves that executes faster, but we currently don't
generate it.
llvm-svn: 21314
Add new ppc beta option related to using condition registers
Make pattern isel control flag (-enable-pattern-isel) global and tristate
0 == off
1 == on
2 == target default
llvm-svn: 21309
This can generate considerably shorter code, reducing the size of crafty
by almost 1%. Also fix the printing of mcrf. The code is currently
disabled until it gets a bit more testing, but should work as-is.
llvm-svn: 21298
Move the transform for select (a < 0) ? b : 0 into the dag from ppc isel
Enable the dag to fold and (setcc, 1) -> setcc for targets where setcc
always produces zero or one.
llvm-svn: 21291
* fold left shifts of 1, 2, 3 or 4 bits into adds
This doesn't save much now, but should get a serious workout once
multiplies by constants get converted to shift/add/sub sequences.
Hold on! :)
llvm-svn: 21282
0x00000..00FFF..FF
^ ^
^ ^
any number of
0's followed by
some number of
1's
then we use dep.z to just paste zeros over the input. For the special
cases where this is zxt1/zxt2/zxt4, we use those instructions instead,
because we're all about readability!!!
that's what it's about!! readability!
*twitch* ;D
llvm-svn: 21279
like this:
ldah $1,1($31)
lda $1,-1($1)
and $0,$1,$24
instead of this:
zap $0,252,$24
To get this back, the selector should recognize the ISD::AND case where this
happens and emit the appropriate ZAP instruction.
llvm-svn: 21270
