[llvm] [InstrProf] Support conditional counter updates for integer counters (PR #109222)
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Wed Sep 18 17:08:31 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
@llvm/pr-subscribers-pgo
Author: Alan Zhao (alanzhao1)
<details>
<summary>Changes</summary>
In #<!-- -->102542. conditional counter updates were only implemented for boolean counters. This PR implements conditional counter updates for integer counters. When the flag -conditional-counter-update is set, integer counters are now treated like boolean counters - @<!-- -->llvm.instrprof.update now checks whether or not a counter is zero, and if not, writes 1 to it.
The motiviation for this mode is that we can bring the benefits of conditional single byte counter updates to languages whose frontends do not support single byte counters (e.g. Rust).
---
Full diff: https://github.com/llvm/llvm-project/pull/109222.diff
2 Files Affected:
- (modified) llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp (+14-2)
- (modified) llvm/test/Instrumentation/InstrProfiling/conditional-counter-updates.ll (+91)
``````````diff
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 014e049ed0d8e5..9d5394deda0856 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -1263,8 +1263,20 @@ void InstrLowerer::lowerIncrement(InstrProfIncrementInst *Inc) {
MaybeAlign(), AtomicOrdering::Monotonic);
} else {
Value *IncStep = Inc->getStep();
- Value *Load = Builder.CreateLoad(IncStep->getType(), Addr, "pgocount");
- auto *Count = Builder.CreateAdd(Load, Inc->getStep());
+ auto *CtrTy = IncStep->getType();
+ Value *Load = Builder.CreateLoad(CtrTy, Addr, "pgocount");
+ Value *Count;
+
+ if (ConditionalCounterUpdate) {
+ Instruction *SplitBefore = Inc->getNextNode();
+ Value *Cmp = Builder.CreateIsNull(Load, "pgocount.ifzero");
+ Instruction *ThenBranch =
+ SplitBlockAndInsertIfThen(Cmp, SplitBefore, false);
+ Builder.SetInsertPoint(ThenBranch);
+ Count = ConstantInt::get(CtrTy, 1);
+ } else {
+ Count = Builder.CreateAdd(Load, Inc->getStep());
+ }
auto *Store = Builder.CreateStore(Count, Addr);
if (isCounterPromotionEnabled())
PromotionCandidates.emplace_back(cast<Instruction>(Load), Store);
diff --git a/llvm/test/Instrumentation/InstrProfiling/conditional-counter-updates.ll b/llvm/test/Instrumentation/InstrProfiling/conditional-counter-updates.ll
index 998443ec0cd568..ebd510cfb5f08a 100644
--- a/llvm/test/Instrumentation/InstrProfiling/conditional-counter-updates.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/conditional-counter-updates.ll
@@ -5,6 +5,9 @@ target triple = "x86_64-unknown-linux-gnu"
@__profn_foo = private constant [3 x i8] c"foo"
@__profn_bar = private constant [3 x i8] c"bar"
+ at __profn_fooint = private constant [6 x i8] c"fooint"
+ at __profn_barint = private constant [6 x i8] c"barint"
+
; CHECK-LABEL: define void @foo
; CHECK-NEXT: %pgocount = load i8, ptr @__profc_foo, align 1
; CHECK-NEXT: %pgocount.ifnonzero = icmp ne i8 %pgocount, 0
@@ -67,3 +70,91 @@ return: ; preds = %if.end, %if.then
%1 = load i32, ptr %retval, align 4
ret i32 %1
}
+
+; CHECK-LABEL: define void @fooint
+; CHECK-NEXT: %pgocount = load i64, ptr @__profc_fooint, align 8
+; CHECK-NEXT: %pgocount.ifzero = icmp eq i64 %pgocount, 0
+; CHECK-NEXT: br i1 %pgocount.ifzero, label %1, label %2
+
+; CHECK-LABEL: 1:
+; CHECK-NEXT: store i64 1, ptr @__profc_fooint, align 8
+; CHECK-NEXT: br label %2
+
+; CHECK-LABEL: 2:
+; CHECK-NEXT: ret void
+define void @fooint() {
+ call void @llvm.instrprof.increment(ptr @__profn_fooint, i64 0, i32 1, i32 0)
+ ret void
+}
+
+; CHECK-LABEL: define i32 @barint
+; CHECK-LABEL: entry:
+; CHECK-NEXT: %retval = alloca i32, align 4
+; CHECK-NEXT: %cond.addr = alloca i32, align 4
+; CHECK-NEXT: store i32 %cond, ptr %cond.addr, align 4
+; CHECK-NEXT: %pgocount = load i64, ptr @__profc_barint, align 8
+; CHECK-NEXT: %pgocount.ifzero = icmp eq i64 %pgocount, 0
+; CHECK-NEXT: br i1 %pgocount.ifzero, label %0, label %1
+
+; CHECK-LABEL: 0: ; preds = %entry
+; CHECK-NEXT: store i64 1, ptr @__profc_barint, align 8
+; CHECK-NEXT: br label %1
+
+; CHECK-LABEL: 1: ; preds = %entry, %0
+; CHECK-NEXT: %2 = load i32, ptr %cond.addr, align 4
+; CHECK-NEXT: %cmp = icmp slt i32 %2, 0
+; CHECK-NEXT: br i1 %cmp, label %if.then, label %if.end
+
+; CHECK-LABEL: if.then: ; preds = %1
+; CHECK-NEXT: %pgocount1 = load i64, ptr getelementptr inbounds ([3 x i64], ptr @__profc_barint, i32 0, i32 1), align 8
+; CHECK-NEXT: %pgocount.ifzero2 = icmp eq i64 %pgocount1, 0
+; CHECK-NEXT: br i1 %pgocount.ifzero2, label %3, label %4
+
+; CHECK-LABEL: 3: ; preds = %if.then
+; CHECK-NEXT: store i64 1, ptr getelementptr inbounds ([3 x i64], ptr @__profc_barint, i32 0, i32 1), align 8
+; CHECK-NEXT: br label %4
+;
+; CHECK-LABEL: 4: ; preds = %if.then, %3
+; CHECK-NEXT: store i32 -1, ptr %retval, align 4
+; CHECK-NEXT: br label %return
+;
+; CHECK-LABEL: if.end: ; preds = %1
+; CHECK-NEXT: %pgocount3 = load i64, ptr getelementptr inbounds ([3 x i64], ptr @__profc_barint, i32 0, i32 2), align 8
+; CHECK-NEXT: %pgocount.ifzero4 = icmp eq i64 %pgocount3, 0
+; CHECK-NEXT: br i1 %pgocount.ifzero4, label %5, label %6
+;
+; CHECK-LABEL: 5: ; preds = %if.end
+; CHECK-NEXT: store i64 1, ptr getelementptr inbounds ([3 x i64], ptr @__profc_barint, i32 0, i32 2), align 8
+; CHECK-NEXT: br label %6
+;
+; CHECK-LABEL: 6: ; preds = %if.end, %5
+; CHECK-NEXT: store i32 0, ptr %retval, align 4
+; CHECK-NEXT: br label %return
+;
+; CHECK-LABEL: return: ; preds = %6, %4
+; CHECK-NEXT: %7 = load i32, ptr %retval, align 4
+; CHECK-NEXT: ret i32 %7
+define i32 @barint(i32 %cond) #0 {
+entry:
+ %retval = alloca i32, align 4
+ %cond.addr = alloca i32, align 4
+ store i32 %cond, ptr %cond.addr, align 4
+ call void @llvm.instrprof.increment(ptr @__profn_barint, i64 0, i32 3, i32 0)
+ %0 = load i32, ptr %cond.addr, align 4
+ %cmp = icmp slt i32 %0, 0
+ br i1 %cmp, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ call void @llvm.instrprof.increment(ptr @__profn_barint, i64 0, i32 3, i32 1)
+ store i32 -1, ptr %retval, align 4
+ br label %return
+
+if.end: ; preds = %entry
+ call void @llvm.instrprof.increment(ptr @__profn_barint, i64 0, i32 3, i32 2)
+ store i32 0, ptr %retval, align 4
+ br label %return
+
+return: ; preds = %if.end, %if.then
+ %1 = load i32, ptr %retval, align 4
+ ret i32 %1
+}
\ No newline at end of file
``````````
</details>
https://github.com/llvm/llvm-project/pull/109222
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