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author | Adam Nemet <anemet@apple.com> | 2015-02-26 17:58:48 +0000 |
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committer | Adam Nemet <anemet@apple.com> | 2015-02-26 17:58:48 +0000 |
commit | e382bb9e353b7eac4ea17487eff1fb48bd7b6b9b (patch) | |
tree | a5625cf4e156c59dd9e5e1c300847b7e522d4371 /test | |
parent | 89e432838138b22042ff7fbd2fe021106284ba0e (diff) |
[LV/LoopAccesses] Backward dependences are not safe just because the
accesses are via different types
Noticed this while generalizing the code for loop distribution.
I confirmed with Arnold that this was indeed a bug and managed to create
a testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230647 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test')
-rw-r--r-- | test/Analysis/LoopAccessAnalysis/backward-dep-different-types.ll | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/test/Analysis/LoopAccessAnalysis/backward-dep-different-types.ll b/test/Analysis/LoopAccessAnalysis/backward-dep-different-types.ll new file mode 100644 index 00000000000..f503a5c6cb8 --- /dev/null +++ b/test/Analysis/LoopAccessAnalysis/backward-dep-different-types.ll @@ -0,0 +1,50 @@ +; RUN: opt -loop-accesses -analyze < %s | FileCheck %s + +; In this loop just because we access A through different types (int, float) +; we still have a dependence cycle: +; +; for (i = 0; i < n; i++) { +; A_float = (float *) A; +; A_float[i + 1] = A[i] * B[i]; +; } + +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.10.0" + +; CHECK: Report: unsafe dependent memory operations in loop +; CHECK-NOT: Memory dependences are safe + +@n = global i32 20, align 4 +@B = common global i32* null, align 8 +@A = common global i32* null, align 8 + +define void @f() { +entry: + %a = load i32** @A, align 8 + %b = load i32** @B, align 8 + br label %for.body + +for.body: ; preds = %for.body, %entry + %storemerge3 = phi i64 [ 0, %entry ], [ %add, %for.body ] + + %arrayidxA = getelementptr inbounds i32* %a, i64 %storemerge3 + %loadA = load i32* %arrayidxA, align 2 + + %arrayidxB = getelementptr inbounds i32* %b, i64 %storemerge3 + %loadB = load i32* %arrayidxB, align 2 + + %mul = mul i32 %loadB, %loadA + + %add = add nuw nsw i64 %storemerge3, 1 + + %a_float = bitcast i32* %a to float* + %arrayidxA_plus_2 = getelementptr inbounds float* %a_float, i64 %add + %mul_float = sitofp i32 %mul to float + store float %mul_float, float* %arrayidxA_plus_2, align 2 + + %exitcond = icmp eq i64 %add, 20 + br i1 %exitcond, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret void +} |