Only emit one PHI node for IV uses with identical bases and strides (after
moving foldable immediates to the load/store instruction).
This implements LoopStrengthReduce/dont_insert_redundant_ops.ll, allowing
us to generate this PPC code for test1:
or r30, r3, r3
.LBB_test1_1: ; Loop
li r2, 0
stw r2, 0(r30)
stw r2, 4(r30)
bl L_pred$stub
addi r30, r30, 8
cmplwi cr0, r3, 0
bne .LBB_test1_1 ; Loop
instead of this code:
or r30, r3, r3
or r29, r3, r3
.LBB_test1_1: ; Loop
li r2, 0
stw r2, 0(r29)
stw r2, 4(r30)
bl L_pred$stub
addi r30, r30, 8 ;; Two iv's with step of 8
addi r29, r29, 8
cmplwi cr0, r3, 0
bne .LBB_test1_1 ; Loop
llvm-svn: 22635
map from instruction* to SCEVHandles. When we delete instructions, we have
to tell it about it. We would run into nasty cases where new instructions
were reallocated at old instruction addresses and get the old map values.
Bad bad bad :(
llvm-svn: 22632
target data to decide which loop induction variables to strength reduce
and how to do so. This work is mostly by Chris Lattner, with tweaks by
me to get it working on some of MultiSource.
llvm-svn: 22558
* Loop invariant code does not dominate the loop header, but rather
the end of the loop preheader.
* The base for a reduced GEP isn't a constant unless all of its
operands (preceding the induction variable) are constant.
* Allow induction variable elimination for the simple case after all.
Also made changes recommended by Chris for properly deleting
instructions.
llvm-svn: 20383
loops. This optimization is not turned on by default yet, but may be run
with the opt tool's -loop-reduce flag. There are many FIXMEs listed in the
code that will make it far more applicable to a wide range of code, but you
have to start somewhere :)
This limited version currently triggers on the following tests in the
MultiSource directory:
pcompress2: 7 times
cfrac: 5 times
anagram: 2 times
ks: 6 times
yacr2: 2 times
llvm-svn: 17134
