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[PGO] Make the PGO instrumentation insert point after alloca #142043

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Merged
merged 2 commits into from
May 30, 2025
Merged

[PGO] Make the PGO instrumentation insert point after alloca #142043

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c987f23
[PGO] Make the PGO instrumentation insert point after alloca
xur-llvm May 29, 2025
a8eb019
Merge branch 'main' into users/xur-llvm/pgowork
xur-llvm May 30, 2025
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8 changes: 4 additions & 4 deletions llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -855,7 +855,7 @@ BasicBlock *FuncPGOInstrumentation<Edge, BBInfo>::getInstrBB(Edge *E) {
auto canInstrument = [](BasicBlock *BB) -> BasicBlock * {
// There are basic blocks (such as catchswitch) cannot be instrumented.
// If the returned first insertion point is the end of BB, skip this BB.
if (BB->getFirstInsertionPt() == BB->end())
if (BB->getFirstNonPHIOrDbgOrAlloca() == BB->end())
return nullptr;
return BB;
};
Expand Down Expand Up @@ -952,7 +952,7 @@ void FunctionInstrumenter::instrument() {
Name, PointerType::get(M.getContext(), 0));
if (PGOFunctionEntryCoverage) {
auto &EntryBB = F.getEntryBlock();
IRBuilder<> Builder(&EntryBB, EntryBB.getFirstInsertionPt());
IRBuilder<> Builder(&EntryBB, EntryBB.getFirstNonPHIOrDbgOrAlloca());
// llvm.instrprof.cover(i8* <name>, i64 <hash>, i32 <num-counters>,
// i32 <index>)
Builder.CreateIntrinsic(
Expand Down Expand Up @@ -1010,7 +1010,7 @@ void FunctionInstrumenter::instrument() {
if (PGOTemporalInstrumentation) {
NumCounters += PGOBlockCoverage ? 8 : 1;
auto &EntryBB = F.getEntryBlock();
IRBuilder<> Builder(&EntryBB, EntryBB.getFirstInsertionPt());
IRBuilder<> Builder(&EntryBB, EntryBB.getFirstNonPHIOrDbgOrAlloca());
// llvm.instrprof.timestamp(i8* <name>, i64 <hash>, i32 <num-counters>,
// i32 <index>)
Builder.CreateIntrinsic(Intrinsic::instrprof_timestamp,
Expand All @@ -1021,7 +1021,7 @@ void FunctionInstrumenter::instrument() {
}

for (auto *InstrBB : InstrumentBBs) {
IRBuilder<> Builder(InstrBB, InstrBB->getFirstInsertionPt());
IRBuilder<> Builder(InstrBB, InstrBB->getFirstNonPHIOrDbgOrAlloca());
assert(Builder.GetInsertPoint() != InstrBB->end() &&
"Cannot get the Instrumentation point");
// llvm.instrprof.increment(i8* <name>, i64 <hash>, i32 <num-counters>,
Expand Down
56 changes: 56 additions & 0 deletions llvm/test/Transforms/PGOProfile/entry_alloca.ll
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@@ -0,0 +1,56 @@
; Note: Make sure that instrumention intrinsic is after entry alloca.
; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s
; RUN: opt < %s -passes=pgo-instr-gen,instrprof -sampled-instrumentation -S | FileCheck %s --check-prefixes=SAMPLE

%struct.A = type { i32, [0 x i32] }
%struct.B = type { i32, [0 x double] }

; CHECK-LABEL: @foo()
; CHECK-NEXT: %1 = alloca %struct.A
; CHECK-NEXT: %2 = alloca %struct.B
; CHECK-NEXT: call void @llvm.instrprof.increment(ptr @__profn_foo

; SAMPLE: @foo()
; SAMPLE-NEXT: %1 = alloca %struct.A
; SAMPLE-NEXT: %2 = alloca %struct.B
; SAMPLE-NEXT: %[[v:[0-9]+]] = load i16, ptr @__llvm_profile_sampling
; SAMPLE-NEXT: {{.*}} = icmp ule i16 %[[v]], 199

define dso_local double @foo() {
%1 = alloca %struct.A, align 4
%2 = alloca %struct.B, align 8
call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %1)
call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %2)
call void @bar(ptr noundef nonnull %1, ptr noundef nonnull %2)
%3 = load i32, ptr %1, align 4
%4 = icmp sgt i32 %3, 0
br i1 %4, label %5, label %21

5:
%6 = getelementptr inbounds i8, ptr %1, i64 4
%7 = getelementptr inbounds i8, ptr %2, i64 8
%8 = zext nneg i32 %3 to i64
br label %9

9:
%10 = phi i64 [ 0, %5 ], [ %19, %9 ]
%11 = phi double [ 0.000000e+00, %5 ], [ %18, %9 ]
%12 = getelementptr inbounds [0 x i32], ptr %6, i64 0, i64 %10
%13 = load i32, ptr %12, align 4
%14 = sitofp i32 %13 to double
%15 = getelementptr inbounds [0 x double], ptr %7, i64 0, i64 %10
%16 = load double, ptr %15, align 8
%17 = fadd double %16, %14
%18 = fadd double %11, %17
%19 = add nuw nsw i64 %10, 1
%20 = icmp eq i64 %19, %8
br i1 %20, label %21, label %9

21:
%22 = phi double [ 0.000000e+00, %0 ], [ %18, %9 ]
call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %2)
call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %1)
ret double %22
}

declare void @bar(ptr noundef, ptr noundef)
1 change: 1 addition & 0 deletions llvm/test/Transforms/PGOProfile/split-indirectbr-critical-edges.ll
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Expand Up @@ -42,6 +42,7 @@ if.end: ; preds = %if.end.preheader, %
;; The edge will not be profiled.
; CHECK-LABEL: @cannot_split(
; CHECK-NEXT: entry:
; CHECK-NEXT: %targets = alloca <2 x ptr>, align 16
; CHECK-NEXT: call void @llvm.instrprof.increment
; CHECK: indirect:
; CHECK-NOT: call void @llvm.instrprof.increment
Expand Down
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