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implement Transforms/LoopStrengthReduce/dont-hoist-simple-loop-constants.ll. 

We used to emit this code for it:

_test:
        li r2, 1     ;; Value tying up a register for the whole loop
        li r5, 0
LBB_test_1:     ; no_exit.2
        or r6, r5, r5
        li r5, 0
        stw r5, 0(r3)
        addi r5, r6, 1
        addi r3, r3, 4
        add r7, r2, r5  ;; should be addi r7, r5, 1
        cmpwi cr0, r7, 701
        blt cr0, LBB_test_1     ; no_exit.2
LBB_test_2:     ; loopexit.2.loopexit
        addi r2, r6, 2
        stw r2, 0(r4)
        blr

now we emit this:

_test:
        li r2, 0
LBB_test_1:     ; no_exit.2
        or r5, r2, r2
        li r2, 0
        stw r2, 0(r3)
        addi r3, r3, 4
        addi r2, r5, 1
        addi r6, r5, 2   ;; whoa, fold those adds!
        cmpwi cr0, r6, 701
        blt cr0, LBB_test_1     ; no_exit.2
LBB_test_2:     ; loopexit.2.loopexit
        addi r2, r5, 2
        stw r2, 0(r4)
        blr

more improvement coming.

llvm-svn: 23306
This commit is contained in:
Chris Lattner 2005-09-10 01:18:45 +00:00
parent 0c7728e4d6
commit 530fe6ab30
1 changed files with 1 additions and 1 deletions
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2
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -826,7 +826,7 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
// this by forcing a noop cast to be inserted into the preheader in this
// case.
if (Constant *C = dyn_cast<Constant>(BaseV))
if (!C->isNullValue()) {
if (!C->isNullValue() && !isTargetConstant(Base)) {
// We want this constant emitted into the preheader!
BaseV = new CastInst(BaseV, BaseV->getType(), "preheaderinsert",
PreInsertPt);