63 lines
3.6 KiB
LLVM
63 lines
3.6 KiB
LLVM
; In this test we check how heuristics for complete unrolling work. We have
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; three knobs:
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; 1) -unroll-threshold
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; 3) -unroll-percent-dynamic-cost-saved-threshold and
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; 2) -unroll-dynamic-cost-savings-discount
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;
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; They control loop-unrolling according to the following rules:
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; * If size of unrolled loop exceeds the absoulte threshold, we don't unroll
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; this loop under any circumstances.
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; * If size of unrolled loop is below the '-unroll-threshold', then we'll
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; consider this loop as a very small one, and completely unroll it.
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; * If a loop size is between these two tresholds, we only do complete unroll
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; it if estimated number of potentially optimized instructions is high (we
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; specify the minimal percent of such instructions).
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; In this particular test-case, complete unrolling will allow later
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; optimizations to remove ~55% of the instructions, the loop body size is 9,
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; and unrolled size is 65.
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; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=20 -unroll-dynamic-cost-savings-discount=0 | FileCheck %s -check-prefix=TEST1
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; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=20 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s -check-prefix=TEST2
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; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=80 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s -check-prefix=TEST3
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; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=100 -unroll-percent-dynamic-cost-saved-threshold=80 -unroll-dynamic-cost-savings-discount=0 | FileCheck %s -check-prefix=TEST4
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; If the absolute threshold is too low, or if we can't optimize away requested
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; percent of instructions, we shouldn't unroll:
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; TEST1: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
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; TEST3: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
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; Otherwise, we should:
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; TEST2-NOT: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
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; Also, we should unroll if the 'unroll-threshold' is big enough:
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; TEST4-NOT: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
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; And check that we don't crash when we're not allowed to do any analysis.
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; RUN: opt < %s -loop-unroll -unroll-max-iteration-count-to-analyze=0 -disable-output
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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@known_constant = internal unnamed_addr constant [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16
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define i32 @foo(i32* noalias nocapture readonly %src) {
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entry:
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br label %loop
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loop: ; preds = %loop, %entry
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%iv = phi i64 [ 0, %entry ], [ %inc, %loop ]
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%r = phi i32 [ 0, %entry ], [ %add, %loop ]
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%arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv
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%src_element = load i32, i32* %arrayidx, align 4
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%array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @known_constant, i64 0, i64 %iv
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%const_array_element = load i32, i32* %array_const_idx, align 4
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%mul = mul nsw i32 %src_element, %const_array_element
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%add = add nsw i32 %mul, %r
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%inc = add nuw nsw i64 %iv, 1
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%exitcond86.i = icmp eq i64 %inc, 9
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br i1 %exitcond86.i, label %loop.end, label %loop
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loop.end: ; preds = %loop
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%r.lcssa = phi i32 [ %r, %loop ]
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ret i32 %r.lcssa
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}
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