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author | Devang Patel <dpatel@apple.com> | 2008-07-09 00:12:01 +0000 |
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committer | Devang Patel <dpatel@apple.com> | 2008-07-09 00:12:01 +0000 |
commit | a5e27f80282d240817d651347a2ddc80a03ee9ce (patch) | |
tree | 0c1a948a5e7011c4dc585f2d72e848dd6fa681ec | |
parent | f877b735ad4987f26cafcbaf22aa4c2199458b5d (diff) | |
download | external_llvm-a5e27f80282d240817d651347a2ddc80a03ee9ce.zip external_llvm-a5e27f80282d240817d651347a2ddc80a03ee9ce.tar.gz external_llvm-a5e27f80282d240817d651347a2ddc80a03ee9ce.tar.bz2 |
If loop induction variable's start value is less then its exit value then do not split the loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53265 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Transforms/Scalar/LoopIndexSplit.cpp | 13 | ||||
-rw-r--r-- | test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll | 2 | ||||
-rw-r--r-- | test/Transforms/LoopIndexSplit/2008-07-08-MisCompilation.ll | 25 |
3 files changed, 39 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp index 45d4900..135ce33 100644 --- a/lib/Transforms/Scalar/LoopIndexSplit.cpp +++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp @@ -384,6 +384,19 @@ void LoopIndexSplit::findLoopConditionals() { BasicBlock *Preheader = L->getLoopPreheader(); StartValue = IndVar->getIncomingValueForBlock(Preheader); } + + // If start value is more then exit value where induction variable + // increments by 1 then we are potentially dealing with an infinite loop. + // Do not index split this loop. + if (ExitCondition) { + ConstantInt *SV = dyn_cast<ConstantInt>(StartValue); + ConstantInt *EV = + dyn_cast<ConstantInt>(ExitCondition->getOperand(ExitValueNum)); + if (SV && EV && SV->getSExtValue() > EV->getSExtValue()) + ExitCondition = NULL; + else if (EV && EV->isZero()) + ExitCondition = NULL; + } } /// Find condition inside a loop that is suitable candidate for index split. diff --git a/test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll b/test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll index 8aa2e52..c4678b4 100644 --- a/test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll +++ b/test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll @@ -24,7 +24,7 @@ bb4.i: ; preds = %bb.i 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] + %tmp11.i = icmp sgt i16 %tmp8.i, 42 ; <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] diff --git a/test/Transforms/LoopIndexSplit/2008-07-08-MisCompilation.ll b/test/Transforms/LoopIndexSplit/2008-07-08-MisCompilation.ll new file mode 100644 index 0000000..7592511 --- /dev/null +++ b/test/Transforms/LoopIndexSplit/2008-07-08-MisCompilation.ll @@ -0,0 +1,25 @@ +; RUN: llvm-as < %s | opt -loop-index-split -stats -disable-output | not grep "1 loop-index-split" +; PR 2487 +@g_6 = external global i32 ; <i32*> [#uses=1] + +define void @func_1() nounwind { +entry: + br label %bb + +bb: ; preds = %bb4, %entry + %l_3.0 = phi i8 [ 0, %entry ], [ %tmp6, %bb4 ] ; <i8> [#uses=2] + %tmp1 = icmp eq i8 %l_3.0, 0 ; <i1> [#uses=1] + br i1 %tmp1, label %bb3, label %bb4 + +bb3: ; preds = %bb + store i32 1, i32* @g_6, align 4 + br label %bb4 + +bb4: ; preds = %bb3, %bb + %tmp6 = add i8 %l_3.0, 1 ; <i8> [#uses=2] + %tmp9 = icmp sgt i8 %tmp6, -1 ; <i1> [#uses=1] + br i1 %tmp9, label %bb, label %return + +return: ; preds = %bb4 + ret void +} |