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[LowerAllowCheckPass] allow to specify runtime.check hotness #145998

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Merged
merged 2 commits into from
Jun 27, 2025
Merged

[LowerAllowCheckPass] allow to specify runtime.check hotness #145998

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997c39c
[𝘀𝗽𝗿] initial version
fmayer Jun 27, 2025
6898193
cmt
fmayer Jun 27, 2025
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1 change: 1 addition & 0 deletions llvm/include/llvm/Transforms/Instrumentation/LowerAllowCheckPass.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ class LowerAllowCheckPass : public PassInfoMixin<LowerAllowCheckPass> {
public:
struct Options {
std::vector<unsigned int> cutoffs;
uint64_t runtime_check;
};

explicit LowerAllowCheckPass(LowerAllowCheckPass::Options Opts)
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13 changes: 13 additions & 0 deletions llvm/lib/Passes/PassBuilder.cpp
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Expand Up @@ -932,6 +932,19 @@ parseLowerAllowCheckPassOptions(StringRef Params) {

Result.cutoffs[index] = cutoff;
}
} else if (ParamName.starts_with("runtime_check")) {
StringRef ValueString;
std::tie(std::ignore, ValueString) = ParamName.split("=");
int runtime_check;
if (ValueString.getAsInteger(0, runtime_check)) {
return make_error<StringError>(
formatv("invalid LowerAllowCheck pass runtime_check parameter '{}' "
"({})",
ValueString, Params)
.str(),
inconvertibleErrorCode());
}
Result.runtime_check = runtime_check;
} else {
return make_error<StringError>(
formatv("invalid LowerAllowCheck pass parameter '{}'", ParamName)
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18 changes: 14 additions & 4 deletions llvm/lib/Transforms/Instrumentation/LowerAllowCheckPass.cpp
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Expand Up @@ -74,7 +74,7 @@ static void emitRemark(IntrinsicInst *II, OptimizationRemarkEmitter &ORE,
static bool removeUbsanTraps(Function &F, const BlockFrequencyInfo &BFI,
const ProfileSummaryInfo *PSI,
OptimizationRemarkEmitter &ORE,
const std::vector<unsigned int> &cutoffs) {
const LowerAllowCheckPass::Options &Opts) {
SmallVector<std::pair<IntrinsicInst *, bool>, 16> ReplaceWithValue;
std::unique_ptr<RandomNumberGenerator> Rng;

Expand All @@ -89,8 +89,10 @@ static bool removeUbsanTraps(Function &F, const BlockFrequencyInfo &BFI,
return HotPercentileCutoff;
else if (II->getIntrinsicID() == Intrinsic::allow_ubsan_check) {
auto *Kind = cast<ConstantInt>(II->getArgOperand(0));
if (Kind->getZExtValue() < cutoffs.size())
return cutoffs[Kind->getZExtValue()];
if (Kind->getZExtValue() < Opts.cutoffs.size())
return Opts.cutoffs[Kind->getZExtValue()];
} else if (II->getIntrinsicID() == Intrinsic::allow_runtime_check) {
return Opts.runtime_check;
}

return 0;
Expand Down Expand Up @@ -157,7 +159,7 @@ PreservedAnalyses LowerAllowCheckPass::run(Function &F,
OptimizationRemarkEmitter &ORE =
AM.getResult<OptimizationRemarkEmitterAnalysis>(F);

return removeUbsanTraps(F, BFI, PSI, ORE, Opts.cutoffs)
return removeUbsanTraps(F, BFI, PSI, ORE, Opts)
// We do not change the CFG, we only replace the intrinsics with
// true or false.
? PreservedAnalyses::none().preserveSet<CFGAnalyses>()
Expand All @@ -182,14 +184,22 @@ void LowerAllowCheckPass::printPipeline(
// correctness.
// TODO: print shorter output by combining adjacent runs, etc.
int i = 0;
bool printed = false;
for (unsigned int cutoff : Opts.cutoffs) {
if (cutoff > 0) {
if (i > 0)
OS << ";";
OS << "cutoffs[" << i << "]=" << cutoff;
printed = true;
}

i++;
}
if (Opts.runtime_check) {
if (printed)
OS << ";";
OS << "runtime_check=" << Opts.runtime_check;
}

OS << '>';
}
9 changes: 9 additions & 0 deletions llvm/test/Transforms/lower-builtin-allow-check-remarks.ll
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Expand Up @@ -4,12 +4,21 @@
; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check)' -lower-allow-check-percentile-cutoff-hot=0 -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s
; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check)' -lower-allow-check-percentile-cutoff-hot=1000000 -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=REMOVE

; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check<cutoffs[7]=0;runtime_check=1000000>)' -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=MIXED
; RUN: opt < %s -passes='require<profile-summary>,function(lower-allow-check<cutoffs[7]=1000000;runtime_check=0>)' -pass-remarks=lower-allow-check -pass-remarks-missed=lower-allow-check -S 2>&1 | FileCheck %s --check-prefixes=MIXED2

; CHECK: remark: <unknown>:0:0: Allowed check: Kind=test_check F=test_runtime BB=entry1
; CHECK: remark: <unknown>:0:0: Allowed check: Kind=7 F=test_ubsan BB=entry2

; REMOVE: remark: <unknown>:0:0: Removed check: Kind=test_check F=test_runtime BB=entry1
; REMOVE: remark: <unknown>:0:0: Removed check: Kind=7 F=test_ubsan BB=entry2

; MIXED: remark: <unknown>:0:0: Removed check: Kind=test_check F=test_runtime BB=entry1
; MIXED: remark: <unknown>:0:0: Allowed check: Kind=7 F=test_ubsan BB=entry2

; MIXED2: remark: <unknown>:0:0: Allowed check: Kind=test_check F=test_runtime BB=entry1
; MIXED2: remark: <unknown>:0:0: Removed check: Kind=7 F=test_ubsan BB=entry2

target triple = "x86_64-pc-linux-gnu"

define i1 @test_runtime() local_unnamed_addr {
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