llvm/lib/Transforms
Chris Lattner ad0124c188 Enhance the shift-shift folding code to allow a no-op cast to occur in between
the shifts.

This allows us to fold this (which is the 'integer add a constant' sequence
from cozmic's scheme compmiler):

int %x(uint %anf-temporary776) {
        %anf-temporary777 = shr uint %anf-temporary776, ubyte 1
        %anf-temporary800 = cast uint %anf-temporary777 to int
        %anf-temporary804 = shl int %anf-temporary800, ubyte 1
        %anf-temporary805 = add int %anf-temporary804, -2
        %anf-temporary806 = or int %anf-temporary805, 1
        ret int %anf-temporary806
}

into this:

int %x(uint %anf-temporary776) {
        %anf-temporary776 = cast uint %anf-temporary776 to int
        %anf-temporary776.mask1 = add int %anf-temporary776, -2
        %anf-temporary805 = or int %anf-temporary776.mask1, 1
        ret int %anf-temporary805
}

note that instcombine already knew how to eliminate the AND that the two
shifts fold into.  This is tested by InstCombine/shift.ll:test26

-Chris


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25128 91177308-0d34-0410-b5e6-96231b3b80d8
2006-01-06 07:52:12 +00:00
..
Hello Remove trailing whitespace 2005-04-21 23:48:37 +00:00
Instrumentation a few more comments on the interfaces and functions 2005-11-28 18:10:59 +00:00
IPO Pull inline methods out of the pass class definition to make it easier to 2006-01-03 19:13:17 +00:00
Scalar Enhance the shift-shift folding code to allow a no-op cast to occur in between 2006-01-06 07:52:12 +00:00
Utils Fix SimplifyCFG/2005-12-03-IncorrectPHIFold.ll 2005-12-03 18:25:58 +00:00
ExprTypeConvert.cpp Now that instcombine does this xform, remove it from the -raise pass 2005-10-29 04:40:23 +00:00
LevelRaise.cpp ConvertibleToGEP always returns 0, remove some old crufty code which 2005-07-26 16:38:28 +00:00
Makefile DONT_BUILD_RELINKED is gone and implied by BUILD_ARCHIVE now 2005-10-24 02:26:13 +00:00
TransformInternals.cpp Remove dead #include 2005-10-29 04:41:30 +00:00
TransformInternals.h ConvertibleToGEP always returns 0, remove some old crufty code which 2005-07-26 16:38:28 +00:00