[llvm] Utils: Add pass to declare runtime libcalls (PR #147534)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Matt Arsenault (arsenm)

<details>
<summary>Changes</summary>

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.

---
Full diff: https://github.com/llvm/llvm-project/pull/147534.diff


7 Files Affected:

- (added) llvm/include/llvm/Transforms/Utils/DeclareRuntimeLibcalls.h (+23) 
- (modified) llvm/lib/Passes/PassBuilder.cpp (+1) 
- (modified) llvm/lib/Passes/PassRegistry.def (+1) 
- (modified) llvm/lib/Transforms/Utils/CMakeLists.txt (+1) 
- (added) llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp (+38) 
- (added) llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll (+15) 
- (modified) llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn (+1) 


``````````diff
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",

``````````

</details>


https://github.com/llvm/llvm-project/pull/147534