[llvm] Utils: Add pass to declare runtime libcalls (PR #147534)
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 8 07:10:35 PDT 2025
https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/147534
This will be useful for testing the set of calls for different systems,
and eventually the product of context specific modifiers applied. In
the future we should also know the type signatures, and be able to
emit the correct one.
>From c8f21f15016de8659d4c192fb9a2389b0cc20a3b Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Tue, 8 Jul 2025 22:39:57 +0900
Subject: [PATCH] Utils: Add pass to declare runtime libcalls
This will be useful for testing the set of calls for different systems,
and eventually the product of context specific modifiers applied. In
the future we should also know the type signatures, and be able to
emit the correct one.
---
.../Transforms/Utils/DeclareRuntimeLibcalls.h | 23 +++++++++++
llvm/lib/Passes/PassBuilder.cpp | 1 +
llvm/lib/Passes/PassRegistry.def | 1 +
llvm/lib/Transforms/Utils/CMakeLists.txt | 1 +
.../Utils/DeclareRuntimeLibcalls.cpp | 38 +++++++++++++++++++
.../Util/DeclareRuntimeLibcalls/basic.ll | 15 ++++++++
.../llvm/lib/Transforms/Utils/BUILD.gn | 1 +
7 files changed, 80 insertions(+)
create mode 100644 llvm/include/llvm/Transforms/Utils/DeclareRuntimeLibcalls.h
create mode 100644 llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
create mode 100644 llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll
diff --git a/llvm/include/llvm/Transforms/Utils/DeclareRuntimeLibcalls.h b/llvm/include/llvm/Transforms/Utils/DeclareRuntimeLibcalls.h
new file mode 100644
index 0000000000000..295e3dec31415
--- /dev/null
+++ b/llvm/include/llvm/Transforms/Utils/DeclareRuntimeLibcalls.h
@@ -0,0 +1,23 @@
+//===- DeclareRuntimeLibcalls.h ---------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_DECLARERUNTIMELIBCALLS_H
+#define LLVM_TRANSFORMS_UTILS_DECLARERUNTIMELIBCALLS_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+class DeclareRuntimeLibcallsPass
+ : public PassInfoMixin<DeclareRuntimeLibcallsPass> {
+public:
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_DECLARERUNTIMELIBCALLS_H
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 874fce05841e2..67800874b0a3f 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -339,6 +339,7 @@
#include "llvm/Transforms/Utils/CountVisits.h"
#include "llvm/Transforms/Utils/DXILUpgrade.h"
#include "llvm/Transforms/Utils/Debugify.h"
+#include "llvm/Transforms/Utils/DeclareRuntimeLibcalls.h"
#include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
#include "llvm/Transforms/Utils/FixIrreducible.h"
#include "llvm/Transforms/Utils/HelloWorld.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index dd3dab3425975..96250772da4a0 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -70,6 +70,7 @@ MODULE_PASS("ctx-prof-flatten-prethinlink",
MODULE_PASS("noinline-nonprevailing", NoinlineNonPrevailing())
MODULE_PASS("deadargelim", DeadArgumentEliminationPass())
MODULE_PASS("debugify", NewPMDebugifyPass())
+MODULE_PASS("declare-runtime-libcalls", DeclareRuntimeLibcallsPass())
MODULE_PASS("dfsan", DataFlowSanitizerPass())
MODULE_PASS("dot-callgraph", CallGraphDOTPrinterPass())
MODULE_PASS("dxil-upgrade", DXILUpgradePass())
diff --git a/llvm/lib/Transforms/Utils/CMakeLists.txt b/llvm/lib/Transforms/Utils/CMakeLists.txt
index 78cad0d253be8..f7e66eca6aeb3 100644
--- a/llvm/lib/Transforms/Utils/CMakeLists.txt
+++ b/llvm/lib/Transforms/Utils/CMakeLists.txt
@@ -20,6 +20,7 @@ add_llvm_component_library(LLVMTransformUtils
CtorUtils.cpp
CountVisits.cpp
Debugify.cpp
+ DeclareRuntimeLibcalls.cpp
DemoteRegToStack.cpp
DXILUpgrade.cpp
EntryExitInstrumenter.cpp
diff --git a/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp b/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
new file mode 100644
index 0000000000000..540039b7d2cbd
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
@@ -0,0 +1,38 @@
+//===- DeclareRuntimeLibcalls.cpp -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Insert declarations for all runtime library calls known for the target.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/DeclareRuntimeLibcalls.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/RuntimeLibcalls.h"
+
+using namespace llvm;
+
+PreservedAnalyses DeclareRuntimeLibcallsPass::run(Module &M,
+ ModuleAnalysisManager &MAM) {
+ RTLIB::RuntimeLibcallsInfo RTLCI(M.getTargetTriple());
+ LLVMContext &Ctx = M.getContext();
+
+ for (RTLIB::LibcallImpl Impl : RTLCI.getLibcallImpls()) {
+ if (Impl == RTLIB::Unsupported)
+ continue;
+
+ // TODO: Declare with correct type, calling convention, and attributes.
+
+ FunctionType *FuncTy =
+ FunctionType::get(Type::getVoidTy(Ctx), {}, /*IsVarArgs=*/true);
+
+ const char *FuncName = RTLCI.getLibcallImplName(Impl);
+ M.getOrInsertFunction(FuncName, FuncTy);
+ }
+
+ return PreservedAnalyses::none();
+}
diff --git a/llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll b/llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll
new file mode 100644
index 0000000000000..ee3a0539bf300
--- /dev/null
+++ b/llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll
@@ -0,0 +1,15 @@
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+; Check an already declared function
+; CHECK: declare float @logf(float)
+declare float @logf(float)
+
+; Check an already defined function
+; CHECK: define float @sinf(float %x) {
+define float @sinf(float %x) {
+ ret float %x
+}
+
+; CHECK: declare void @acosf(...)
+; CHECK: declare void @__umodti3(...)
+
diff --git a/llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn b/llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn
index b16fe19bddfd1..d327e810c536d 100644
--- a/llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn
@@ -29,6 +29,7 @@ static_library("Utils") {
"CtorUtils.cpp",
"DXILUpgrade.cpp",
"Debugify.cpp",
+ "DeclareRuntimeLibcalls.cpp",
"DemoteRegToStack.cpp",
"EntryExitInstrumenter.cpp",
"EscapeEnumerator.cpp",
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