[PseudoProbe] Do not emit pseudo probes when module is not probed.

[hoy]

Summary

There is a case when a function has pseudo probe intrinsics but the module it resides does not have the probe desc. This could happen when the current module is not built with -fpseudo-probe-for-profiling while a function in it calls some other function from a probed module. In thinLTO mode, the callee function could be imported and inlined into the current function.
While this is undefined behavior, I'm fixing the asm printer to not ICE and warn user about this.

[wenlei]

It is possible to let users know when this happens? Ideally it's something user need to fix - pass flags consistently.

[hoy]

Warn user of non-probed importing modules.

[wenlei]

llvm/lib/Linker/IRMover.cpp

1238–1242

Suggest rephrase the warning message with something like: Pseudo-probe ignored: source module (<module name>) is compiled with -fpseudo-probe-for-profiling while destination module (<module name>) is not.

[hoy]

llvm/lib/Linker/IRMover.cpp

1238–1242

Sounds good.

[hoy]

Updating D121737: [PseudoProbe] Do not emit pseudo probes when module is not probed.

[wenlei]

lgtm, thanks.

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

for (const MachineBasicBlock &MBB : MF) {
     // always be computed from their offsets.
     emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), MBBSymbol);
     OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
   }
   OutStreamer->PopSection();
 }
 
 void AsmPrinter::emitPseudoProbe(const MachineInstr &MI) {
+  if (PP) {
     auto GUID = MI.getOperand(0).getImm();
     auto Index = MI.getOperand(1).getImm();
     auto Type = MI.getOperand(2).getImm();
     auto Attr = MI.getOperand(3).getImm();
     DILocation *DebugLoc = MI.getDebugLoc();
     PP->emitPseudoProbe(GUID, Index, Type, Attr, DebugLoc);
   }
+}
 
 void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
   if (!MF.getTarget().Options.EmitStackSizeSection)
     return;
 
   MCSection *StackSizeSection =
       getObjFileLowering().getStackSizesSection(*getCurrentSection());
   if (!StackSizeSection)

llvm/lib/Linker/IRMover.cpp

 void IRLinker::linkNamedMDNodes() {
   const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
   for (const NamedMDNode &NMD : SrcM->named_metadata()) {
     // Don't link module flags here. Do them separately.
     if (&NMD == SrcModFlags)
       continue;
     // Don't import pseudo probe descriptors here for thinLTO. They will be
     // emitted by the originating module.
-    if (IsPerformingImport && NMD.getName() == PseudoProbeDescMetadataName)
+    if (IsPerformingImport && NMD.getName() == PseudoProbeDescMetadataName) {
+      if (!DstM.getNamedMetadata(NMD.getName()))
+        emitWarning("Pseudo-probe ignored: source module '" +
+                    SrcM->getModuleIdentifier() +
+                    "' is compiled with -fpseudo-probe-for-profiling while "
+                    "destination module '" +
+                    DstM.getModuleIdentifier() + "' is not\n");
       continue;
+    }
     NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());
     // Add Src elements into Dest node.
     for (const MDNode *Op : NMD.operands())
       DestNMD->addOperand(Mapper.mapMDNode(*Op));
   }
 }
 
 /// Merge the linker flags in Src into the Dest module.

llvm/test/ThinLTO/X86/pseudo-probe-desc-import.ll

-; RUN: opt -module-summary %s -o %t1.bc
+; RUN: opt -module-summary -passes=pseudo-probe %s -o %t1.bc
 ; RUN: opt -module-summary %p/Inputs/pseudo-probe-desc-import.ll -o %t2.bc
 ; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t1.bc %t2.bc
 
 ; Don't import pseudo probe desc.
 ; RUN: llvm-lto -thinlto-action=import %t1.bc -thinlto-index=%t.index.bc -o - | llvm-dis -o - | FileCheck %s
+
+
+; Warn that current module is not pseudo-probe instrumented.
+; RUN: opt -module-summary %s -o %t3.bc
+; RUN: llvm-lto -thinlto-action=thinlink -o %t3.index.bc %t3.bc %t2.bc
+; RUN: llvm-lto -thinlto-action=import %t3.bc -thinlto-index=%t3.index.bc -o /dev/null 2>&1 | FileCheck %s  --check-prefix=WARN
+
+
 ; CHECK-NOT: {i64 6699318081062747564, i64 4294967295, !"foo"
 ; CHECK: !{i64 -2624081020897602054, i64 281479271677951, !"main"
 
+; WARN: warning: Pseudo-probe ignored: source module '{{.*}}' is compiled with -fpseudo-probe-for-profiling while destination module '{{.*}}' is not
+
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define i32 @main() {
 entry:
   call void (...) @foo()
-  call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 1, i32 0, i64 -1)
   ret i32 0
 }
 
 declare void @foo(...)
 
-declare void @llvm.pseudoprobe(i64, i64, i32, i64) #0
-
 attributes #0 = { inaccessiblememonly nounwind willreturn }
-
-!llvm.pseudo_probe_desc = !{!0}
-
-!0 = !{i64 -2624081020897602054, i64 281479271677951, !"main", null}