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780ffd9c1f
li r2, 0
LBB_test_1: ; no_exit.2
li r5, 0
stw r5, 0(r3)
addi r2, r2, 1
addi r3, r3, 4
cmpwi cr0, r2, 701
blt cr0, LBB_test_1 ; no_exit.2
LBB_test_2: ; loopexit.2.loopexit
addi r2, r2, 1
stw r2, 0(r4)
blr
[zion ~/llvm]$ cat > ~/xx
Uses of IV's outside of the loop should use hte post-incremented version
of the IV, not the preincremented version. This helps many loops (e.g. in sixtrack)
which used to generate code like this (this is the code from the
dont-hoist-simple-loop-constants.ll testcase):
_test:
li r2, 0 **** IV starts at 0
LBB_test_1: ; no_exit.2
or r5, r2, r2 **** Copy for loop exit
li r2, 0
stw r2, 0(r3)
addi r3, r3, 4
addi r2, r5, 1
addi r6, r5, 2 **** IV+2
cmpwi cr0, r6, 701
blt cr0, LBB_test_1 ; no_exit.2
LBB_test_2: ; loopexit.2.loopexit
addi r2, r5, 2 **** IV+2
stw r2, 0(r4)
blr
And now generated code like this:
_test:
li r2, 1 *** IV starts at 1
LBB_test_1: ; no_exit.2
li r5, 0
stw r5, 0(r3)
addi r2, r2, 1
addi r3, r3, 4
cmpwi cr0, r2, 701 *** IV.postinc + 0
blt cr0, LBB_test_1
LBB_test_2: ; loopexit.2.loopexit
stw r2, 0(r4) *** IV.postinc + 0
blr
llvm-svn: 23313