[LLVM][Analysis] Add a pass to print unknown intrinsics

[jurahul]

Add a pass that will print unknown intrinsics, which is a function whose name starts with llvm. but is not a intrinsic recognized by LLVM.

This can help debug issues such as
StanfordLegion/legion#1865 (comment) (by running this pass on the libdevice.10.bc file that ships with the CUDA Toolkit)

[jurahul]

Since using libdevice that ships with CUDA Toolkit with the LLVM upstream NVPTX backend is a common use case for projects like XLA/Triton/Legion, this pass can be helpful to detect any mismatch between the intrinsics supported by upstream LLVM vs what is present in libdevice shipped with CUDA Toollkit. Apart from this specific use case, it seems this pass can have general utility and is simple enough, hence creating this PR for committing it upstream.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Author: Rahul Joshi (jurahul)

Changes

Add a pass that will print unknown intrinsics, which is a function whose name starts with llvm. but is not a intrinsic regonized by LLVM.

This can help debug issues such as
StanfordLegion/legion#1865 (comment) (by running this pass on the libdevice.10.bc file that ships with the CUDA Toolkit)

---

Full diff: https://github.com/llvm/llvm-project/pull/145985.diff

6 Files Affected:

• (added) llvm/include/llvm/Analysis/UnknownIntrinsicPrinter.h (+26)
• (modified) llvm/lib/Analysis/CMakeLists.txt (+1)
• (added) llvm/lib/Analysis/UnknownIntrinsicPrinter.cpp (+25)
• (modified) llvm/lib/Passes/PassBuilder.cpp (+1)
• (modified) llvm/lib/Passes/PassRegistry.def (+1)
• (added) llvm/test/Analysis/UnknownIntrinsicPrinter/unknown.ll (+25)

diff --git a/llvm/include/llvm/Analysis/UnknownIntrinsicPrinter.h b/llvm/include/llvm/Analysis/UnknownIntrinsicPrinter.h
new file mode 100644
index 0000000000000..d81047545ab4d
--- /dev/null
+++ b/llvm/include/llvm/Analysis/UnknownIntrinsicPrinter.h
@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_ANALYSIS_UNKNOWNINTRINSICPRINTER_H
+#define LLVM_ANALYSIS_UNKNOWNINTRINSICPRINTER_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+class UnknownIntrinsicPrinterPass
+    : public PassInfoMixin<UnknownIntrinsicPrinterPass> {
+  raw_ostream &OS;
+
+public:
+  UnknownIntrinsicPrinterPass(raw_ostream &OS) : OS(OS) {}
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+  static bool isRequired() { return true; }
+};
+} // namespace llvm
+
+#endif // LLVM_ANALYSIS_UNKNOWNINTRINSICPRINTER_H
diff --git a/llvm/lib/Analysis/CMakeLists.txt b/llvm/lib/Analysis/CMakeLists.txt
index cfde787b17790..a35d6ccd35437 100644
--- a/llvm/lib/Analysis/CMakeLists.txt
+++ b/llvm/lib/Analysis/CMakeLists.txt
@@ -155,6 +155,7 @@ add_llvm_component_library(LLVMAnalysis
   TypeBasedAliasAnalysis.cpp
   TypeMetadataUtils.cpp
   UniformityAnalysis.cpp
+  UnknownIntrinsicPrinter.cpp
   ScopedNoAliasAA.cpp
   ValueLattice.cpp
   ValueLatticeUtils.cpp
diff --git a/llvm/lib/Analysis/UnknownIntrinsicPrinter.cpp b/llvm/lib/Analysis/UnknownIntrinsicPrinter.cpp
new file mode 100644
index 0000000000000..f04efa07cd6c4
--- /dev/null
+++ b/llvm/lib/Analysis/UnknownIntrinsicPrinter.cpp
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/UnknownIntrinsicPrinter.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Module.h"
+
+using namespace llvm;
+
+PreservedAnalyses UnknownIntrinsicPrinterPass::run(Module &M,
+                                                   ModuleAnalysisManager &) {
+  for (const Function &F : M.functions()) {
+    // An unknown intrinsic is a function that begins with "llvm." but is not
+    // a recognized intrinsic (i.e., it's IntrinsicID is not_intrinsic).
+    if (F.isIntrinsic() && F.getIntrinsicID() == Intrinsic::not_intrinsic)
+      OS << "Unknown intrinsic : " << F.getName() << '\n';
+  }
+  return PreservedAnalyses::all();
+}
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 4603eaff8ade9..7676295f3b183 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -77,6 +77,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
 #include "llvm/Analysis/UniformityAnalysis.h"
+#include "llvm/Analysis/UnknownIntrinsicPrinter.h"
 #include "llvm/CodeGen/AssignmentTrackingAnalysis.h"
 #include "llvm/CodeGen/AtomicExpand.h"
 #include "llvm/CodeGen/BasicBlockSectionsProfileReader.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index ec14c6a9211d9..af5ef2bd88fdb 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -138,6 +138,7 @@ MODULE_PASS("print<inline-advisor>", InlineAdvisorAnalysisPrinterPass(errs()))
 MODULE_PASS("print<ir2vec>", IR2VecPrinterPass(errs()))
 MODULE_PASS("print<module-debuginfo>", ModuleDebugInfoPrinterPass(errs()))
 MODULE_PASS("print<reg-usage>", PhysicalRegisterUsageInfoPrinterPass(errs()))
+MODULE_PASS("print-unknown-intrinsics", UnknownIntrinsicPrinterPass(errs()))
 MODULE_PASS("pseudo-probe", SampleProfileProbePass(TM))
 MODULE_PASS("pseudo-probe-update", PseudoProbeUpdatePass())
 MODULE_PASS("recompute-globalsaa", RecomputeGlobalsAAPass())
diff --git a/llvm/test/Analysis/UnknownIntrinsicPrinter/unknown.ll b/llvm/test/Analysis/UnknownIntrinsicPrinter/unknown.ll
new file mode 100644
index 0000000000000..941caf1a36bb7
--- /dev/null
+++ b/llvm/test/Analysis/UnknownIntrinsicPrinter/unknown.ll
@@ -0,0 +1,25 @@
+; RUN: opt -disable-output -passes=print-unknown-intrinsics %s 2>&1 | FileCheck %s
+
+; ------------------------------------------------------------------------------
+; Add several known intrinsics.
+declare i8 @llvm.ctpop.i8(i8)
+declare double @llvm.sqrt.f64(double)
+
+; Note, the next two are known intrinsics because automatic remanging of
+; intrinsics will convert them to the "correct" name.
+
+; Remangled to llvm.sqrt.f64(double).
+declare double @llvm.sqrt.foo(double)
+
+; Remangled to llvm.ctpop.i8(i8).
+declare i8 @llvm.ctpop.unknown.i8(i8)
+
+; ------------------------------------------------------------------------------
+; Add several unknown intrinsics.
+declare i1 @llvm.isunordered.f32(float, float)
+declare i8 @llvm.foo.unknown.i8(i8)
+declare i8 @llvm.unknown.i8(i8)
+
+; CHECK: Unknown intrinsic : llvm.isunordered.f32
+; CHECK: Unknown intrinsic : llvm.foo.unknown.i8
+; CHECK: Unknown intrinsic : llvm.unknown.i8