Report an error by default instead of a warning

Report an error by default. Add a new flag -bpf-disable-check-unreachable-ir to disable checking.
llvm · Feb 21, 2025 · 1c19bae · 1c19bae
1 parent fcbcd8e
commit 1c19bae
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Showing 6 changed files with 41 additions and 31 deletions.
diff --git a/llvm/lib/Target/BPF/BPF.h b/llvm/lib/Target/BPF/BPF.h
@@ -22,7 +22,7 @@ class BPFTargetMachine;
 class InstructionSelector;
 class PassRegistry;
 
-ModulePass *createBPFCheckUndefIR();
+ModulePass *createBPFCheckUnreachableIR();
 ModulePass *createBPFCheckAndAdjustIR();
 
 FunctionPass *createBPFISelDag(BPFTargetMachine &TM);
@@ -35,7 +35,7 @@ InstructionSelector *createBPFInstructionSelector(const BPFTargetMachine &,
                                                   const BPFSubtarget &,
                                                   const BPFRegisterBankInfo &);
 
-void initializeBPFCheckUndefIRPass(PassRegistry &);
+void initializeBPFCheckUnreachableIRPass(PassRegistry &);
 void initializeBPFCheckAndAdjustIRPass(PassRegistry&);
 void initializeBPFDAGToDAGISelLegacyPass(PassRegistry &);
 void initializeBPFMIPeepholePass(PassRegistry &);

diff --git a/llvm/lib/Target/BPF/BPFCheckUndefIR.cpp → .../lib/Target/BPF/BPFCheckUnreachableIR.cpp b/llvm/lib/Target/BPF/BPFCheckUndefIR.cpp → .../lib/Target/BPF/BPFCheckUnreachableIR.cpp
@@ -1,12 +1,12 @@
-//===---------------- BPFAdjustOpt.cpp - Adjust Optimization --------------===//
+//===--------- BPFCheckUnreachableIR.cpp - Issue Unreachable Error --------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
-// Check 'unreachable' IRs and issue proper warnings.
+// Check 'unreachable' IRs and issue proper errors.
 //
 //===----------------------------------------------------------------------===//
 
@@ -19,34 +19,41 @@
 #include "llvm/IR/Value.h"
 #include "llvm/Pass.h"
 
-#define DEBUG_TYPE "bpf-check-undef-ir"
+#define DEBUG_TYPE "bpf-check-unreachable-ir"
 
 using namespace llvm;
 
+static cl::opt<bool>
+    DisableCheckUnreachableIR("bpf-disable-check-unreachable-ir", cl::Hidden,
+                              cl::desc("BPF: Disable Checking Unreachable IR"),
+                              cl::init(false));
+
 namespace {
 
-class BPFCheckUndefIR final : public ModulePass {
+class BPFCheckUnreachableIR final : public ModulePass {
   bool runOnModule(Module &F) override;
 
 public:
   static char ID;
-  BPFCheckUndefIR() : ModulePass(ID) {}
+  BPFCheckUnreachableIR() : ModulePass(ID) {}
 
 private:
-  void BPFCheckUndefIRImpl(Function &F);
+  void BPFCheckUnreachableIRImpl(Function &F);
   void BPFCheckInst(Function &F, BasicBlock &BB, Instruction &I);
   void HandleUnreachableInsn(Function &F, BasicBlock &BB, Instruction &I);
 };
 } // End anonymous namespace
 
-char BPFCheckUndefIR::ID = 0;
-INITIALIZE_PASS(BPFCheckUndefIR, DEBUG_TYPE, "BPF Check Undef IRs", false,
-                false)
+char BPFCheckUnreachableIR::ID = 0;
+INITIALIZE_PASS(BPFCheckUnreachableIR, DEBUG_TYPE, "BPF Check Unreachable IRs",
+                false, false)
 
-ModulePass *llvm::createBPFCheckUndefIR() { return new BPFCheckUndefIR(); }
+ModulePass *llvm::createBPFCheckUnreachableIR() {
+  return new BPFCheckUnreachableIR();
+}
 
-void BPFCheckUndefIR::HandleUnreachableInsn(Function &F, BasicBlock &BB,
-                                            Instruction &I) {
+void BPFCheckUnreachableIR::HandleUnreachableInsn(Function &F, BasicBlock &BB,
+                                                  Instruction &I) {
   // LLVM may create a switch statement with default to a 'unreachable' basic
   // block. Do not warn for such cases.
   unsigned NumNoSwitches = 0, NumSwitches = 0;
@@ -73,17 +80,18 @@ void BPFCheckUndefIR::HandleUnreachableInsn(Function &F, BasicBlock &BB,
   F.getContext().diagnose(
       DiagnosticInfoGeneric(Twine("unreachable in func ")
                                 .concat(F.getName())
-                                .concat(", due to uninitialized variable?"),
-                            DS_Warning));
+                                .concat(", due to uninitialized variable?")
+                                .concat(" try -Wuninitialized?"),
+                            DS_Error));
 }
 
-void BPFCheckUndefIR::BPFCheckInst(Function &F, BasicBlock &BB,
-                                   Instruction &I) {
+void BPFCheckUnreachableIR::BPFCheckInst(Function &F, BasicBlock &BB,
+                                         Instruction &I) {
   if (I.getOpcode() == Instruction::Unreachable)
     HandleUnreachableInsn(F, BB, I);
 }
 
-void BPFCheckUndefIR::BPFCheckUndefIRImpl(Function &F) {
+void BPFCheckUnreachableIR::BPFCheckUnreachableIRImpl(Function &F) {
   // A 'unreachable' will be added to the end of naked function.
   // Let ignore these naked functions.
   if (F.hasFnAttribute(Attribute::Naked))
@@ -95,8 +103,10 @@ void BPFCheckUndefIR::BPFCheckUndefIRImpl(Function &F) {
   }
 }
 
-bool BPFCheckUndefIR::runOnModule(Module &M) {
+bool BPFCheckUnreachableIR::runOnModule(Module &M) {
+  if (DisableCheckUnreachableIR)
+    return false;
   for (Function &F : M)
-    BPFCheckUndefIRImpl(F);
+    BPFCheckUnreachableIRImpl(F);
   return false;
 }
diff --git a/llvm/lib/Target/BPF/BPFTargetMachine.cpp b/llvm/lib/Target/BPF/BPFTargetMachine.cpp
@@ -45,7 +45,7 @@ extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
 
   PassRegistry &PR = *PassRegistry::getPassRegistry();
   initializeGlobalISel(PR);
-  initializeBPFCheckUndefIRPass(PR);
+  initializeBPFCheckUnreachableIRPass(PR);
   initializeBPFCheckAndAdjustIRPass(PR);
   initializeBPFMIPeepholePass(PR);
   initializeBPFDAGToDAGISelLegacyPass(PR);
@@ -144,7 +144,7 @@ void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
 }
 
 void BPFPassConfig::addIRPasses() {
-  addPass(createBPFCheckUndefIR());
+  addPass(createBPFCheckUnreachableIR());
   addPass(createAtomicExpandLegacyPass());
   addPass(createBPFCheckAndAdjustIR());
 

diff --git a/llvm/lib/Target/BPF/CMakeLists.txt b/llvm/lib/Target/BPF/CMakeLists.txt
@@ -26,7 +26,7 @@ add_llvm_target(BPFCodeGen
   BPFAsmPrinter.cpp
   BPFASpaceCastSimplifyPass.cpp
   BPFCheckAndAdjustIR.cpp
-  BPFCheckUndefIR.cpp
+  BPFCheckUnreachableIR.cpp
   BPFFrameLowering.cpp
   BPFInstrInfo.cpp
   BPFIRPeephole.cpp

diff --git a/llvm/test/CodeGen/BPF/naked-fn-with-frame-pointer.ll b/llvm/test/CodeGen/BPF/naked-fn-with-frame-pointer.ll
@@ -37,5 +37,5 @@ define dso_local void @normal() "frame-pointer"="all" {
 ; CHECK-BE-NEXT:  # %bb.0:
 ; CHECK-BE-NEXT:    call main
   call void @main()
-  unreachable
+  ret void
 }
diff --git a/llvm/test/CodeGen/BPF/store_imm.ll b/llvm/test/CodeGen/BPF/store_imm.ll
@@ -13,7 +13,7 @@ define void @byte(ptr %p0) {
   store volatile i8  1, ptr %p0, align 1
   store volatile i8 -1, ptr %p1, align 1
 
-  unreachable
+  ret void
 }
 
 define void @half(ptr, ptr %p0) {
@@ -26,7 +26,7 @@ define void @half(ptr, ptr %p0) {
   store volatile i16  1, ptr %p0, align 2
   store volatile i16 -1, ptr %p1, align 2
 
-  unreachable
+  ret void
 }
 
 define void @word(ptr, ptr, ptr %p0) {
@@ -47,7 +47,7 @@ define void @word(ptr, ptr, ptr %p0) {
   store volatile i32  4294967295, ptr %p3, align 4
   store volatile i32  4294967296, ptr %p3, align 4
 
-  unreachable
+  ret void
 }
 
 define void @dword(ptr, ptr, ptr, ptr %p0) {
@@ -69,7 +69,7 @@ define void @dword(ptr, ptr, ptr, ptr %p0) {
   store volatile i64 -2000000000, ptr %p2, align 8
   store volatile i64  4294967295, ptr %p3, align 8
 
-  unreachable
+  ret void
 }
 
 define void @unaligned(ptr %p0) {
@@ -88,7 +88,7 @@ define void @unaligned(ptr %p0) {
   store volatile i32 -2, ptr %p1, align 2
   store volatile i64 -2, ptr %p2, align 4
 
-  unreachable
+  ret void
 }
 
 define void @inline_asm(ptr %p0) {
@@ -100,5 +100,5 @@ define void @inline_asm(ptr %p0) {
 ; CHECK-NEXT:    #NO_APP
   call void asm "*(u32 *)(r0 + 42) = 7;", "~{r0},~{mem}"()
 
-  unreachable
+  ret void
 }