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| author | Nick Lewycky <nicholas@mxc.ca> | 2008-12-09 07:25:04 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2008-12-09 07:25:04 +0000 |
| commit | 0bed364307fa5c009239e65352ed36cb451953a7 (patch) | |
| tree | ed089200a639c85fd6dd3eb12808f44baac70028 | |
| parent | ba4dacc8752f1af5ca7a153cfeae4d6e4f78ba8f (diff) | |
It's easy to handle SLE/SGE when the loop has a unit stride.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60748 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 6 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/2008-12-08-FiniteSGE.ll | 24 |
2 files changed, 29 insertions, 1 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 2b714de3b3..c9af6de79d 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2924,8 +2924,12 @@ bool ScalarEvolutionsImpl::potentialInfiniteLoop(SCEV *Stride, SCEV *RHS, if (!R) return true; - if (isSigned) + if (isSigned) { + if (SC->getValue()->isOne()) + return R->getValue()->isMaxValue(true); + return true; // XXX: because we don't have an sdiv scev. + } // If negative, it wraps around every iteration, but we don't care about that. APInt S = SC->getValue()->getValue().abs(); diff --git a/test/Analysis/ScalarEvolution/2008-12-08-FiniteSGE.ll b/test/Analysis/ScalarEvolution/2008-12-08-FiniteSGE.ll new file mode 100644 index 0000000000..a9a7c05658 --- /dev/null +++ b/test/Analysis/ScalarEvolution/2008-12-08-FiniteSGE.ll @@ -0,0 +1,24 @@ +; RUN: llvm-as < %s | opt -analyze -scalar-evolution | grep {255 iterations} + +define i32 @foo(i32 %x, i32 %y, i32* %lam, i32* %alp) nounwind { +bb1.thread: + br label %bb1 + +bb1: ; preds = %bb1, %bb1.thread + %indvar = phi i32 [ 0, %bb1.thread ], [ %indvar.next, %bb1 ] ; <i32> [#uses=4] + %i.0.reg2mem.0 = sub i32 255, %indvar ; <i32> [#uses=2] + %0 = getelementptr i32* %alp, i32 %i.0.reg2mem.0 ; <i32*> [#uses=1] + %1 = load i32* %0, align 4 ; <i32> [#uses=1] + %2 = getelementptr i32* %lam, i32 %i.0.reg2mem.0 ; <i32*> [#uses=1] + store i32 %1, i32* %2, align 4 + %3 = sub i32 254, %indvar ; <i32> [#uses=1] + %4 = icmp slt i32 %3, 0 ; <i1> [#uses=1] + %indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1] + br i1 %4, label %bb2, label %bb1 + +bb2: ; preds = %bb1 + %tmp10 = mul i32 %indvar, %x ; <i32> [#uses=1] + %z.0.reg2mem.0 = add i32 %tmp10, %y ; <i32> [#uses=1] + %5 = add i32 %z.0.reg2mem.0, %x ; <i32> [#uses=1] + ret i32 %5 +} |