[llvm-branch-commits] [llvm] [Instrumentor] Add a global function regexp to limit the instrumentation (PR #196234)
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Wed May 6 23:47:42 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Johannes Doerfert (jdoerfert)
<details>
<summary>Changes</summary>
Only functions that match the "function_regex" will be instrumented, or if they have the instrumentation attribute.
---
Full diff: https://github.com/llvm/llvm-project/pull/196234.diff
5 Files Affected:
- (modified) llvm/include/llvm/Transforms/IPO/Instrumentor.h (+7-1)
- (modified) llvm/lib/Transforms/IPO/Instrumentor.cpp (+20-2)
- (modified) llvm/test/Instrumentation/Instrumentor/default_config.json (+3-1)
- (added) llvm/test/Instrumentation/Instrumentor/function_regex.json (+26)
- (added) llvm/test/Instrumentation/Instrumentor/function_regex.ll (+57)
``````````diff
diff --git a/llvm/include/llvm/Transforms/IPO/Instrumentor.h b/llvm/include/llvm/Transforms/IPO/Instrumentor.h
index 9bd809230d14d..a5859fc20505c 100644
--- a/llvm/include/llvm/Transforms/IPO/Instrumentor.h
+++ b/llvm/include/llvm/Transforms/IPO/Instrumentor.h
@@ -355,7 +355,12 @@ struct InstrumentationConfig {
TargetRegex = BaseConfigurationOption::getStringOption(
*this, "target_regex",
"Regular expression to be matched against the module target. "
- "Only targets that match this regex will be instrumented",
+ "Only targets that match this regex will be instrumented.",
+ "");
+ FunctionRegex = BaseConfigurationOption::getStringOption(
+ *this, "function_regex",
+ "Regular expression to be matched against a function name. "
+ "Only functions that match this regex will be instrumented.",
"");
HostEnabled = BaseConfigurationOption::getBoolOption(
*this, "host_enabled", "Instrument non-GPU targets", true);
@@ -419,6 +424,7 @@ struct InstrumentationConfig {
BaseConfigurationOption *RuntimeStubsFile;
BaseConfigurationOption *DemangleFunctionNames;
BaseConfigurationOption *TargetRegex;
+ BaseConfigurationOption *FunctionRegex;
BaseConfigurationOption *HostEnabled;
BaseConfigurationOption *GPUEnabled;
diff --git a/llvm/lib/Transforms/IPO/Instrumentor.cpp b/llvm/lib/Transforms/IPO/Instrumentor.cpp
index 0265447832357..9fd04ab911135 100644
--- a/llvm/lib/Transforms/IPO/Instrumentor.cpp
+++ b/llvm/lib/Transforms/IPO/Instrumentor.cpp
@@ -154,6 +154,9 @@ class InstrumentorImpl final {
/// The instrumentor configuration.
InstrumentationConfig &IConf;
+ /// The function regex filter, if any.
+ Regex ParsedFunctionRegex;
+
/// The underlying module.
Module &M;
@@ -171,7 +174,7 @@ bool InstrumentorImpl::shouldInstrumentTarget() {
bool RegexMatches = true;
const auto TargetRegexStr = IConf.TargetRegex->getString();
if (!TargetRegexStr.empty()) {
- llvm::Regex TargetRegex(TargetRegexStr);
+ Regex TargetRegex(TargetRegexStr);
std::string ErrMsg;
if (!TargetRegex.isValid(ErrMsg)) {
IIRB.Ctx.diagnose(DiagnosticInfoInstrumentation(
@@ -190,7 +193,11 @@ bool InstrumentorImpl::shouldInstrumentTarget() {
bool InstrumentorImpl::shouldInstrumentFunction(Function &Fn) {
if (Fn.isDeclaration())
return false;
- return !Fn.getName().starts_with(IConf.getRTName()) ||
+ bool RegexMatches = true;
+ const auto FunctionRegexStr = IConf.FunctionRegex->getString();
+ if (!FunctionRegexStr.empty())
+ RegexMatches = ParsedFunctionRegex.match(Fn.getName());
+ return (RegexMatches && !Fn.getName().starts_with(IConf.getRTName())) ||
Fn.hasFnAttribute("instrument");
}
@@ -274,6 +281,17 @@ bool InstrumentorImpl::instrument() {
if (!shouldInstrumentTarget())
return Changed;
+ const auto FunctionRegexStr = IConf.FunctionRegex->getString();
+ if (!FunctionRegexStr.empty()) {
+ ParsedFunctionRegex = Regex(FunctionRegexStr);
+ std::string ErrMsg;
+ if (!ParsedFunctionRegex.isValid(ErrMsg)) {
+ IIRB.Ctx.diagnose(DiagnosticInfoInstrumentation(
+ Twine("failed to parse target regex: ") + ErrMsg, DS_Warning));
+ return false;
+ }
+ }
+
for (auto &It : IConf.IChoices[InstrumentationLocation::INSTRUCTION_PRE])
if (It.second->Enabled)
InstChoicesPRE[It.second->getOpcode()] = It.second;
diff --git a/llvm/test/Instrumentation/Instrumentor/default_config.json b/llvm/test/Instrumentation/Instrumentor/default_config.json
index 295adfe0bd96e..86b81a9568de6 100644
--- a/llvm/test/Instrumentation/Instrumentor/default_config.json
+++ b/llvm/test/Instrumentation/Instrumentor/default_config.json
@@ -7,7 +7,9 @@
"demangle_function_names": true,
"demangle_function_names.description": "Demangle functions names passed to the runtime.",
"target_regex": "",
- "target_regex.description": "Regular expression to be matched against the module target. Only targets that match this regex will be instrumented",
+ "target_regex.description": "Regular expression to be matched against the module target. Only targets that match this regex will be instrumented.",
+ "function_regex": "",
+ "function_regex.description": "Regular expression to be matched against a function name. Only functions that match this regex will be instrumented.",
"host_enabled": true,
"host_enabled.description": "Instrument non-GPU targets",
"gpu_enabled": true,
diff --git a/llvm/test/Instrumentation/Instrumentor/function_regex.json b/llvm/test/Instrumentation/Instrumentor/function_regex.json
new file mode 100644
index 0000000000000..91435c73f0f20
--- /dev/null
+++ b/llvm/test/Instrumentation/Instrumentor/function_regex.json
@@ -0,0 +1,26 @@
+{
+ "configuration": {
+ "runtime_prefix": "__instrumentor_",
+ "function_regex": "foo|baz"
+ },
+ "instruction_pre": {
+ "load": {
+ "enabled": true,
+ "id": true
+ },
+ "store": {
+ "enabled": true,
+ "id": false
+ }
+ },
+ "instruction_post": {
+ "load": {
+ "enabled": true,
+ "id": true
+ },
+ "store": {
+ "enabled": true,
+ "id": true
+ }
+ }
+}
diff --git a/llvm/test/Instrumentation/Instrumentor/function_regex.ll b/llvm/test/Instrumentation/Instrumentor/function_regex.ll
new file mode 100644
index 0000000000000..29e28611aa114
--- /dev/null
+++ b/llvm/test/Instrumentation/Instrumentor/function_regex.ll
@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instrumentor -instrumentor-read-config-file=%S/function_regex.json -S | FileCheck %s
+
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define i32 @foo() {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = alloca i32, align 4
+; CHECK-NEXT: call void @__instrumentor_pre_store() #[[ATTR0:[0-9]+]]
+; CHECK-NEXT: store i32 0, ptr [[TMP0]], align 4
+; CHECK-NEXT: call void @__instrumentor_post_store(i32 -1) #[[ATTR0]]
+; CHECK-NEXT: call void @__instrumentor_pre_load(i32 2) #[[ATTR0]]
+; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4
+; CHECK-NEXT: call void @__instrumentor_post_load(i32 -2) #[[ATTR0]]
+; CHECK-NEXT: ret i32 [[TMP1]]
+;
+entry:
+ %0 = alloca i32, align 4
+ store i32 0, ptr %0, align 4
+ %2 = load i32, ptr %0, align 4
+ ret i32 %2
+}
+
+define i32 @bar() {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = alloca i32, align 4
+; CHECK-NEXT: store i32 0, ptr [[TMP0]], align 4
+; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4
+; CHECK-NEXT: ret i32 [[TMP1]]
+;
+entry:
+ %0 = alloca i32, align 4
+ store i32 0, ptr %0, align 4
+ %2 = load i32, ptr %0, align 4
+ ret i32 %2
+}
+
+define i32 @baz() {
+; CHECK-LABEL: @baz(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = alloca i32, align 4
+; CHECK-NEXT: call void @__instrumentor_pre_store() #[[ATTR0]]
+; CHECK-NEXT: store i32 0, ptr [[TMP0]], align 4
+; CHECK-NEXT: call void @__instrumentor_post_store(i32 -3) #[[ATTR0]]
+; CHECK-NEXT: call void @__instrumentor_pre_load(i32 4) #[[ATTR0]]
+; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4
+; CHECK-NEXT: call void @__instrumentor_post_load(i32 -4) #[[ATTR0]]
+; CHECK-NEXT: ret i32 [[TMP1]]
+;
+entry:
+ %0 = alloca i32, align 4
+ store i32 0, ptr %0, align 4
+ %2 = load i32, ptr %0, align 4
+ ret i32 %2
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/196234
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