[llvm] [profdata] Consume reader error if returned early (PR #163671)

[Ellis Hoag via llvm-commits]

https://github.com/ellishg created https://github.com/llvm/llvm-project/pull/163671

https://github.com/llvm/llvm-project/pull/69513 added logic to emit an error when something goes wrong in `readRawCounts()` by passing a `Warn()` lambda to capture errors. If we capture an error in this way and we also early return due to some other error (say from `readBinaryIds()`) then we will hit an assert due to an unconsumed error. This is because we don't consume the error at the end of this function.

https://github.com/llvm/llvm-project/blob/1c7ae8927439e5dbc3c1e9a9df4769ace491f9f6/llvm/tools/llvm-profdata/llvm-profdata.cpp#L864-L867

Fix this assert by calling `consumeError()` via `llvm::make_scope_exit()` when the function returns for any reason.

We might be able to simplify this by directly adding the error to `WC->Errors` in `Warn()`, but that might change the order of the errors reported and I am less confident in that change.

>From f8d6f056b20558e05faab7a070f2ae60643685e3 Mon Sep 17 00:00:00 2001
From: Ellis Hoag <ellishoag at meta.com>
Date: Wed, 15 Oct 2025 17:57:15 -0700
Subject: [PATCH 1/2] [profdata] Consume reader error if returned early

---
 llvm/tools/llvm-profdata/llvm-profdata.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/llvm/tools/llvm-profdata/llvm-profdata.cpp b/llvm/tools/llvm-profdata/llvm-profdata.cpp
index 15ddb05f953ee..7be3fcf475a94 100644
--- a/llvm/tools/llvm-profdata/llvm-profdata.cpp
+++ b/llvm/tools/llvm-profdata/llvm-profdata.cpp
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
@@ -778,6 +779,10 @@ loadInput(const WeightedFile &Input, SymbolRemapper *Remapper,
   // we have more non-fatal errors from InstrProfReader in the future. How
   // should this interact with different -failure-mode?
   std::optional<std::pair<Error, std::string>> ReaderWarning;
+  auto ReaderWarningScope = llvm::make_scope_exit([&] {
+    if (ReaderWarning)
+      consumeError(std::move(ReaderWarning->first));
+  });
   auto Warn = [&](Error E) {
     if (ReaderWarning) {
       consumeError(std::move(E));

>From 68fa9c45f10b13f079a204723407470cba6aa73e Mon Sep 17 00:00:00 2001
From: Ellis Hoag <ellishoag at meta.com>
Date: Wed, 15 Oct 2025 18:03:20 -0700
Subject: [PATCH 2/2] add comment

---
 llvm/tools/llvm-profdata/llvm-profdata.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/tools/llvm-profdata/llvm-profdata.cpp b/llvm/tools/llvm-profdata/llvm-profdata.cpp
index 7be3fcf475a94..585a39de9985f 100644
--- a/llvm/tools/llvm-profdata/llvm-profdata.cpp
+++ b/llvm/tools/llvm-profdata/llvm-profdata.cpp
@@ -780,6 +780,8 @@ loadInput(const WeightedFile &Input, SymbolRemapper *Remapper,
   // should this interact with different -failure-mode?
   std::optional<std::pair<Error, std::string>> ReaderWarning;
   auto ReaderWarningScope = llvm::make_scope_exit([&] {
+    // If we hit a different error we may still have an error in ReaderWarning.
+    // Consume it now to avoid an assert
     if (ReaderWarning)
       consumeError(std::move(ReaderWarning->first));
   });