[LTO] Avoid assert fail on failed pass plugin load #96691
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Without this patch, passing -load-pass-plugin=nonexistent.so to llvm-lto2 produces a backtrace because LTOBackend.cpp does not handle the error correctly: ``` Failed to load passes from 'nonexistant.so'. Request ignored. Expected<T> must be checked before access or destruction. Unchecked Expected<T> contained error: Could not load library 'nonexistant.so': nonexistant.so: cannot open shared object file: No such file or directoryPLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace. ``` Any tool using `lto::Config::PassPlugins` should suffer similarly. Based on the message "Request ignored" and the continue statement in the implementation, this patch assumes the intention was not to cause the program to fail.
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@llvm/pr-subscribers-lto Author: Joel E. Denny (jdenny-ornl) ChangesWithout this patch, passing -load-pass-plugin=nonexistent.so to llvm-lto2 produces a backtrace because LTOBackend.cpp does not handle the error correctly: Any tool using Based on the message "Request ignored" and the continue statement in the implementation, this patch assumes the intention was not to cause the program to fail. Full diff: https://github.com/llvm/llvm-project/pull/96691.diff 2 Files Affected:
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index 84a69d9ff1a1f..7931108c0ec99 100644
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -192,8 +192,9 @@ static void RegisterPassPlugins(ArrayRef<std::string> PassPlugins,
for (auto &PluginFN : PassPlugins) {
auto PassPlugin = PassPlugin::Load(PluginFN);
if (!PassPlugin) {
- errs() << "Failed to load passes from '" << PluginFN
- << "'. Request ignored.\n";
+ errs() << "Failed to load passes from plugin '" << PluginFN
+ << "' (request ignored): " << toString(PassPlugin.takeError())
+ << "\n";
continue;
}
diff --git a/llvm/test/Feature/load_plugin_error.ll b/llvm/test/Feature/load_plugin_error.ll
index 24a7cce5d8d39..2b860a901ee41 100644
--- a/llvm/test/Feature/load_plugin_error.ll
+++ b/llvm/test/Feature/load_plugin_error.ll
@@ -1,5 +1,18 @@
-; REQUIRES: plugins, examples
+; REQUIRES: plugins
; UNSUPPORTED: target={{.*windows.*}}
-; RUN: not opt < %s -load-pass-plugin=%t/nonexistant.so -disable-output 2>&1 | FileCheck %s
-; CHECK: Could not load library {{.*}}nonexistant.so
+; RUN: not opt < %s -load-pass-plugin=%t/nonexistent.so -disable-output 2>&1 | FileCheck %s
+
+; RUN: opt %s -o %t.o
+; RUN: llvm-lto2 run -load-pass-plugin=%t/nonexistent.so %t.o -o %t \
+; RUN: -r %t.o,test 2>&1 | \
+; RUN: FileCheck %s
+
+; CHECK: Could not load library {{.*}}nonexistent.so
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @test() {
+ ret void
+}
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jhuber6
approved these changes
Jun 25, 2024
I'm happy to change it to be like opt. After all, stopping on failure to load a plugin is what lto already does without this patch (but it's a crash). |
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Yeah, crashing on an unhandled error is definitely incorrect, whether or not it should be ignored is a different issue but I can see the rationale. I think |
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I just mean to point out that apparently no one has been too dependent on its ability to continue given that it currently crashes. |
Based on the message "Request ignored" and the continue statement, the intention was apparently to continue on failure to load a plugin. However, no one appears to rely on that behavior now given that it crashes instead, and terminating is consistent with opt.
jhuber6
approved these changes
Jun 25, 2024
serge-sans-paille
approved these changes
Jun 26, 2024
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Thanks for the reviews. |
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LGTM. Ideally LTOBackend.cpp should have a better error reporting mechanism than we do not need so many |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/620 Here is the relevant piece of the build log for the reference: |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/744 Here is the relevant piece of the build log for the reference: |
This one blamed only me, but it looks irrelevant, and it passed on the next build. |
I pushed a commit to hopefully fix that and other bot fails. |
lravenclaw
pushed a commit
to lravenclaw/llvm-project
that referenced
this pull request
Jul 3, 2024
Without this patch, passing -load-pass-plugin=nonexistent.so to llvm-lto2 produces a backtrace because LTOBackend.cpp does not handle the error correctly: ``` Failed to load passes from 'nonexistant.so'. Request ignored. Expected<T> must be checked before access or destruction. Unchecked Expected<T> contained error: Could not load library 'nonexistant.so': nonexistant.so: cannot open shared object file: No such file or directoryPLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace. ``` Any tool using `lto::Config::PassPlugins` should suffer similarly. Based on the message "Request ignored" and the continue statement, the intention was apparently to continue on failure to load a plugin. However, no one appears to rely on that behavior now given that it crashes instead, and terminating is consistent with opt.
AlexisPerry
pushed a commit
to llvm-project-tlp/llvm-project
that referenced
this pull request
Jul 9, 2024
Without this patch, passing -load-pass-plugin=nonexistent.so to llvm-lto2 produces a backtrace because LTOBackend.cpp does not handle the error correctly: ``` Failed to load passes from 'nonexistant.so'. Request ignored. Expected<T> must be checked before access or destruction. Unchecked Expected<T> contained error: Could not load library 'nonexistant.so': nonexistant.so: cannot open shared object file: No such file or directoryPLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace. ``` Any tool using `lto::Config::PassPlugins` should suffer similarly. Based on the message "Request ignored" and the continue statement, the intention was apparently to continue on failure to load a plugin. However, no one appears to rely on that behavior now given that it crashes instead, and terminating is consistent with opt.
jdenny-ornl
added a commit
to jdenny-ornl/llvm-project
that referenced
this pull request
Jul 10, 2024
The original version was introduced here in 2476cd3.
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Without this patch, passing -load-pass-plugin=nonexistent.so to llvm-lto2 produces a backtrace because LTOBackend.cpp does not handle the error correctly:
Any tool using
lto::Config::PassPluginsshould suffer similarly.Based on the message "Request ignored" and the continue statement, the intention was apparently to continue on failure to load a plugin. However, no one appears to rely on that behavior now given that it crashes instead, and terminating is consistent with opt.