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[TypeProf][ICP]Allow vtable-comparison as long as vtable count is comparable with function count for each candidate #106260

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Merged
merged 1 commit into from
Aug 27, 2024
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[TypeProf][ICP]Allow vtable-comparison as long as vtable count is comparable with function count for each candidate #106260

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10 changes: 1 addition & 9 deletions llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ static cl::opt<bool>
// Indirect call promotion pass will fall back to function-based comparison if
// vtable-count / function-count is smaller than this threshold.
static cl::opt<float> ICPVTablePercentageThreshold(
"icp-vtable-percentage-threshold", cl::init(0.99), cl::Hidden,
"icp-vtable-percentage-threshold", cl::init(0.995), cl::Hidden,
cl::desc("The percentage threshold of vtable-count / function-count for "
"cost-benefit analysis."));

Expand Down Expand Up @@ -888,14 +888,6 @@ bool IndirectCallPromoter::isProfitableToCompareVTables(
}
}

// If the indirect fallback is not cold, don't compare vtables.
if (PSI && PSI->hasProfileSummary() &&
!PSI->isColdCount(RemainingVTableCount)) {
LLVM_DEBUG(dbgs() << " Indirect fallback basic block is not cold. Bail "
"out for vtable comparison.\n");
return false;
}

return true;
}

Expand Down
18 changes: 18 additions & 0 deletions llvm/test/Transforms/PGOProfile/icp_vtable_cmp.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,7 @@ declare i32 @Base2_foo(ptr)
declare i32 @Base1_foo(ptr)
declare void @Base3_foo(ptr)

!llvm.module.flags = !{!11}
!0 = !{i64 16, !"Base1"}
!1 = !{i64 40, !"Base1"}
!2 = !{i64 16, !"Base2"}
Expand All @@ -131,6 +132,23 @@ declare void @Base3_foo(ptr)
!8 = !{i64 16, !"Derived3"}
!9 = !{!"VP", i32 2, i64 1600, i64 -4123858694673519054, i64 600, i64 -7211198353767973908, i64 500, i64 -3574436251470806727, i64 200, i64 6288809125658696740, i64 200, i64 12345678, i64 100}
!10 = !{!"VP", i32 0, i64 1600, i64 3827408714133779784, i64 600, i64 5837445539218476403, i64 500, i64 -9064955852395570538, i64 400, i64 56781234, i64 100}

!11 = !{i32 1, !"ProfileSummary", !12}
!12 = !{!13, !14, !15, !16, !17, !18, !19, !20}
!13 = !{!"ProfileFormat", !"InstrProf"}
!14 = !{!"TotalCount", i64 10000}
!15 = !{!"MaxCount", i64 10}
!16 = !{!"MaxInternalCount", i64 1}
!17 = !{!"MaxFunctionCount", i64 1000}
!18 = !{!"NumCounts", i64 3}
!19 = !{!"NumFunctions", i64 3}
!20 = !{!"DetailedSummary", !21}
!21 = !{!22, !23, !24}
!22 = !{i32 10000, i64 101, i32 1}
!23 = !{i32 990000, i64 101, i32 1}
!24 = !{i32 999999, i64 1, i32 2}


;.
; VTABLE-COMMON: [[PROF9]] = !{!"VP", i32 2, i64 100, i64 12345678, i64 100}
; VTABLE-COMMON: [[PROF10]] = !{!"branch_weights", i32 600, i32 1000}
Expand Down
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