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Add minimum count threshold for indirect call promotion #145282

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Merged
merged 3 commits into from
Jun 26, 2025
Merged

Add minimum count threshold for indirect call promotion #145282

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592ed4b
Add minimum count threshold for indirect call promotion
snehasish Jun 23, 2025
5b0b5ff
Drop redundant test case, MIN-COUNT-BLOCK.
snehasish Jun 26, 2025
0d5b60e
Address comments.
snehasish Jun 26, 2025
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11 changes: 9 additions & 2 deletions llvm/lib/Analysis/IndirectCallPromotionAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,18 @@ static cl::opt<unsigned> ICPRemainingPercentThreshold(

// The percent threshold for the direct-call target (this call site vs the
// total call count) for it to be considered as the promotion target.
static cl::opt<unsigned>
static cl::opt<uint64_t>
ICPTotalPercentThreshold("icp-total-percent-threshold", cl::init(5),
cl::Hidden,
cl::desc("The percentage threshold against total "
"count for the promotion"));

// Set the minimum absolute count threshold for indirect call promotion.
// Candidates with counts below this threshold will not be promoted.
static cl::opt<unsigned> ICPMinimumCountThreshold(
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Should this be uint64_t to match the type of the Count it is being compared against?

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Done.

"icp-minimum-count-threshold", cl::init(0), cl::Hidden,
cl::desc("Minimum absolute count for promotion candidate"));

// Set the maximum number of targets to promote for a single indirect-call
// callsite.
static cl::opt<unsigned>
Expand All @@ -51,7 +57,8 @@ cl::opt<unsigned> MaxNumVTableAnnotations(
bool ICallPromotionAnalysis::isPromotionProfitable(uint64_t Count,
uint64_t TotalCount,
uint64_t RemainingCount) {
return Count * 100 >= ICPRemainingPercentThreshold * RemainingCount &&
return Count >= ICPMinimumCountThreshold &&
Count * 100 >= ICPRemainingPercentThreshold * RemainingCount &&
Count * 100 >= ICPTotalPercentThreshold * TotalCount;
}

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14 changes: 14 additions & 0 deletions llvm/test/Transforms/PGOProfile/indirect_call_promotion.ll
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Original file line number Diff line number Diff line change
@@ -1,6 +1,10 @@
; RUN: opt < %s -passes=pgo-icall-prom -S -icp-total-percent-threshold=50 | FileCheck %s --check-prefix=ICALL-PROM
; RUN: opt < %s -passes=pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-remaining-percent-threshold=0 -icp-total-percent-threshold=0 -icp-max-prom=4 2>&1 | FileCheck %s --check-prefix=PASS-REMARK
; RUN: opt < %s -passes=pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-remaining-percent-threshold=0 -icp-total-percent-threshold=20 -icp-max-prom=4 2>&1 | FileCheck %s --check-prefix=PASS2-REMARK
; Test minimum count threshold - should prevent func1 promotion (count 10 < threshold 15)
; RUN: opt < %s -passes=pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-minimum-count-threshold=15 -icp-remaining-percent-threshold=0 -icp-total-percent-threshold=0 -icp-max-prom=4 2>&1 | FileCheck %s --check-prefix=MIN-COUNT-15
; Test edge case - threshold exactly at count value
; RUN: opt < %s -passes=pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-minimum-count-threshold=10 -icp-remaining-percent-threshold=0 -icp-total-percent-threshold=0 -icp-max-prom=4 2>&1 | FileCheck %s --check-prefix=MIN-COUNT-10

; PASS-REMARK: remark: <unknown>:0:0: Promote indirect call to func4 with count 1030 out of 1600
; PASS-REMARK: remark: <unknown>:0:0: Promote indirect call to func2 with count 410 out of 570
Expand All @@ -12,6 +16,16 @@
; PASS2-REMARK-NOT: remark: <unknown>:0:0: Promote indirect call to func3
; PASS2-REMARK-NOT: remark: <unknown>:0:0: Promote indirect call to func1

; MIN-COUNT-15: remark: <unknown>:0:0: Promote indirect call to func4 with count 1030 out of 1600
; MIN-COUNT-15: remark: <unknown>:0:0: Promote indirect call to func2 with count 410 out of 570
; MIN-COUNT-15: remark: <unknown>:0:0: Promote indirect call to func3 with count 150 out of 160
; MIN-COUNT-15-NOT: remark: <unknown>:0:0: Promote indirect call to func1

; MIN-COUNT-10: remark: <unknown>:0:0: Promote indirect call to func4 with count 1030 out of 1600
; MIN-COUNT-10: remark: <unknown>:0:0: Promote indirect call to func2 with count 410 out of 570
; MIN-COUNT-10: remark: <unknown>:0:0: Promote indirect call to func3 with count 150 out of 160
; MIN-COUNT-10: remark: <unknown>:0:0: Promote indirect call to func1 with count 10 out of 10

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

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