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Do not erase induction variable increment if it is used outside the loop. 

llvm-svn: 51280
This commit is contained in:
Devang Patel 2008-05-19 22:23:55 +00:00
parent 123438cc05
commit ee7bf41c06
2 changed files with 61 additions and 4 deletions
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20
llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
View File

@ -596,12 +596,28 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
if (isa<PHINode>(I) || I == LTerminator)
continue;
if (I == IndVarIncrement)
if (I == IndVarIncrement) {
// Replace induction variable increment if it is not used outside
// the loop.
bool UsedOutsideLoop = false;
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
if (Instruction *Use = dyn_cast<Instruction>(UI))
if (!L->contains(Use->getParent())) {
UsedOutsideLoop = true;
break;
}
}
if (!UsedOutsideLoop) {
I->replaceAllUsesWith(ExitValue);
else
I->eraseFromParent();
}
}
else {
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
}
}
LPM->deleteLoopFromQueue(L);

41
llvm/test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll Normal file
View File

@ -0,0 +1,41 @@
; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | grep tmp8 | count 3
; count 3 = increment + phi + store
;PR2294
@g_2 = external global i16 ; <i16*> [#uses=4]
@g_5 = external global i32 ; <i32*> [#uses=1]
@.str = external constant [4 x i8] ; <[4 x i8]*> [#uses=1]
declare void @func_1() nounwind
define i32 @main() nounwind {
entry:
%tmp101.i = load i16* @g_2, align 2 ; <i16> [#uses=1]
%tmp112.i = icmp sgt i16 %tmp101.i, 0 ; <i1> [#uses=1]
br i1 %tmp112.i, label %bb.preheader.i, label %func_1.exit
bb.preheader.i: ; preds = %entry
%g_2.promoted.i = load i16* @g_2 ; <i16> [#uses=1]
br label %bb.i
bb.i: ; preds = %bb6.i, %bb.preheader.i
%g_2.tmp.0.i = phi i16 [ %g_2.promoted.i, %bb.preheader.i ], [ %tmp8.i, %bb6.i ] ; <i16> [#uses=2]
%tmp2.i = icmp eq i16 %g_2.tmp.0.i, 0 ; <i1> [#uses=1]
br i1 %tmp2.i, label %bb4.i, label %bb6.i
bb4.i: ; preds = %bb.i
%tmp5.i = volatile load i32* @g_5, align 4 ; <i32> [#uses=0]
br label %bb6.i
bb6.i: ; preds = %bb4.i, %bb.i
%tmp8.i = add i16 %g_2.tmp.0.i, 1 ; <i16> [#uses=3]
%tmp11.i = icmp sgt i16 %tmp8.i, 0 ; <i1> [#uses=1]
br i1 %tmp11.i, label %bb.i, label %return.loopexit.i
return.loopexit.i: ; preds = %bb6.i
%tmp8.i.lcssa = phi i16 [ %tmp8.i, %bb6.i ] ; <i16> [#uses=1]
store i16 %tmp8.i.lcssa, i16* @g_2
br label %func_1.exit
func_1.exit: ; preds = %return.loopexit.i, %entry
%tmp1 = load i16* @g_2, align 2 ; <i16> [#uses=1]
%tmp12 = sext i16 %tmp1 to i32 ; <i32> [#uses=1]
%tmp3 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @.str, i32 0, i32 0), i32 %tmp12 ) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @printf(i8*, ...) nounwind