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[LoopRotate] Add test to track update for inaccurate branch weight #86495

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merged 1 commit into from
Mar 28, 2024
Merged

[LoopRotate] Add test to track update for inaccurate branch weight #86495

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42 changes: 42 additions & 0 deletions llvm/test/Transforms/LoopRotate/update-branch-weights.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,46 @@ loop_exit:
ret void
}

; BFI_BEFORE-LABEL: block-frequency-info: func6_inaccurate_branch_weight
; BFI_BEFORE: - entry: {{.*}} count = 1024
; BFI_BEFORE: - loop_header: {{.*}} count = 2047
; BFI_BEFORE: - loop_body: {{.*}} count = 1023
; BFI_BEFORE: - loop_exit: {{.*}} count = 1024

; BFI_AFTER-LABEL: block-frequency-info: func6_inaccurate_branch_weight
; BFI_AFTER: - entry: {{.*}} count = 1024
; BFI_AFTER: - loop_body: {{.*}} count = 4294967296
; BFI_AFTER: - loop_exit: {{.*}} count = 1024

; IR-LABEL: define void @func6_inaccurate_branch_weight(
; IR: entry:
; IR: br label %loop_body
; IR: loop_body:
; IR: br i1 %cmp, label %loop_body, label %loop_exit, !prof [[PROF_FUNC6_0:![0-9]+]]
; IR: loop_exit:
; IR: ret void

; Branch weight from sample-based PGO may be inaccurate due to sampling.
; Count for loop_body in following case should be not less than loop_exit.
; However this may not hold for Sample-based PGO.
define void @func6_inaccurate_branch_weight() !prof !3 {
entry:
br label %loop_header

loop_header:
%i = phi i32 [0, %entry], [%i_inc, %loop_body]
%cmp = icmp slt i32 %i, 2
br i1 %cmp, label %loop_body, label %loop_exit, !prof !9

loop_body:
store volatile i32 %i, ptr @g, align 4
%i_inc = add i32 %i, 1
br label %loop_header

loop_exit:
ret void
}

!0 = !{!"function_entry_count", i64 1}
!1 = !{!"branch_weights", i32 1000, i32 1}
!2 = !{!"branch_weights", i32 3000, i32 1000}
Expand All @@ -241,6 +281,7 @@ loop_exit:
!6 = !{!"branch_weights", i32 0, i32 1}
!7 = !{!"branch_weights", i32 1, i32 0}
!8 = !{!"branch_weights", i32 0, i32 0}
!9 = !{!"branch_weights", i32 1023, i32 1024}

; IR: [[PROF_FUNC0_0]] = !{!"branch_weights", i32 2000, i32 1000}
; IR: [[PROF_FUNC0_1]] = !{!"branch_weights", i32 999, i32 1}
Expand All @@ -251,3 +292,4 @@ loop_exit:
; IR: [[PROF_FUNC3_0]] = !{!"branch_weights", i32 0, i32 1}
; IR: [[PROF_FUNC4_0]] = !{!"branch_weights", i32 1, i32 0}
; IR: [[PROF_FUNC5_0]] = !{!"branch_weights", i32 0, i32 0}
; IR: [[PROF_FUNC6_0]] = !{!"branch_weights", i32 -1, i32 1024}