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In the last change to IRCE the BPI is ignored if BFI is present, however BFI and BPI have a different thresholds. Specifically BPI approach checks only latch exit probability so it is expected if the loop has only one exit block (latch) the behavior with BFI and BPI should be the same, BPI approach by default uses threshold 10, so it considers the loop with estimated number of iterations less then 10 should not be considered for IRCE optimization. BFI approach uses the default value 3 and this is inconsistent. The CL modifies the code to use the same threshold for both approaches.. The test is updated due to it has two side-exits (except latch) and each of them has a probability 1/16, so BFI estimates the number of runtime iteration is about to 7 (1/16 + 1/16 + some for latch) and test fails. Reviewers: mkazantsev, ebrevnov Reviewed By: mkazantsev Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D91230
44 lines
1.4 KiB
LLVM
44 lines
1.4 KiB
LLVM
; RUN: opt -verify-loop-info -irce-print-changed-loops -passes=irce -irce-min-runtime-iterations=3 < %s 2>&1 | FileCheck %s --check-prefixes=CHECK-NO
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; RUN: opt -verify-loop-info -irce-print-changed-loops -passes=irce -irce-min-runtime-iterations=0 < %s 2>&1 | FileCheck %s --check-prefixes=CHECK-YES
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; CHECK-YES: constrained Loop
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; CHECK-NO-NOT: constrained Loop
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define i32 @multiple_access_no_preloop(
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i32* %arr_a, i32* %a_len_ptr, i32* %arr_b, i32* %b_len_ptr, i32 %n) {
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entry:
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%len.a = load i32, i32* %a_len_ptr, !range !0
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%first.itr.check = icmp sgt i32 %n, 0
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br i1 %first.itr.check, label %loop, label %exit, !prof !1
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loop:
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%idx = phi i32 [ 0, %entry ] , [ %idx.next, %backedge ]
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%idx.next = add i32 %idx, 1
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%abc.a = icmp slt i32 %idx, %len.a
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br i1 %abc.a, label %in.bounds.a, label %exit, !prof !2
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in.bounds.a:
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%addr.a = getelementptr i32, i32* %arr_a, i32 %idx
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%val = load i32, i32* %addr.a
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%cond = icmp ne i32 %val, 0
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; Most probable exit from a loop.
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br i1 %cond, label %found, label %backedge, !prof !3
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backedge:
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%next = icmp slt i32 %idx.next, %n
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br i1 %next, label %loop, label %exit, !prof !4
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found:
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ret i32 %val
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exit:
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ret i32 0
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}
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!0 = !{i32 0, i32 2147483647}
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!1 = !{!"branch_weights", i32 1024, i32 1}
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!2 = !{!"branch_weights", i32 512, i32 1}
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!3 = !{!"branch_weights", i32 1, i32 2}
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!4 = !{!"branch_weights", i32 512, i32 1}
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