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Diffstat (limited to 'llvm/test/Transforms/LoopUnroll/full-unroll-heuristics-dce.ll')
| -rw-r--r-- | llvm/test/Transforms/LoopUnroll/full-unroll-heuristics-dce.ll | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/llvm/test/Transforms/LoopUnroll/full-unroll-heuristics-dce.ll b/llvm/test/Transforms/LoopUnroll/full-unroll-heuristics-dce.ll new file mode 100644 index 00000000000..6ee73b6fe4f --- /dev/null +++ b/llvm/test/Transforms/LoopUnroll/full-unroll-heuristics-dce.ll @@ -0,0 +1,38 @@ +; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=100 -unroll-dynamic-cost-savings-discount=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=60 | FileCheck %s +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" + +@known_constant = internal unnamed_addr constant [10 x i32] [i32 0, i32 0, i32 0, i32 0, i32 1, i32 0, i32 0, i32 0, i32 0, i32 0], align 16 + +; If a load becomes a constant after loop unrolling, we sometimes can simplify +; CFG. This test verifies that we handle such cases. +; After one operand in an instruction is constant-folded and the +; instruction is simplified, the other operand might become dead. +; In this test we have:: +; for i in 1..10: +; r += A[i] * B[i] +; A[i] is 0 almost at every iteration, so there is no need in loading B[i] at +; all. + + +; CHECK-LABEL: @unroll_dce +; CHECK-NOT: br i1 %exitcond, label %for.end, label %for.body +define i32 @unroll_dce(i32* noalias nocapture readonly %b) { +entry: + br label %for.body + +for.body: ; preds = %for.body, %entry + %iv.0 = phi i64 [ 0, %entry ], [ %iv.1, %for.body ] + %r.0 = phi i32 [ 0, %entry ], [ %r.1, %for.body ] + %arrayidx1 = getelementptr inbounds [10 x i32], [10 x i32]* @known_constant, i64 0, i64 %iv.0 + %x1 = load i32, i32* %arrayidx1, align 4 + %arrayidx2 = getelementptr inbounds i32, i32* %b, i64 %iv.0 + %x2 = load i32, i32* %arrayidx2, align 4 + %mul = mul i32 %x1, %x2 + %r.1 = add i32 %mul, %r.0 + %iv.1 = add nuw nsw i64 %iv.0, 1 + %exitcond = icmp eq i64 %iv.1, 10 + br i1 %exitcond, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret i32 %r.1 +} |
