https://github.com/llvmbot created
https://github.com/llvm/llvm-project/pull/134711
Backport 268c065eab06b81a0d7256ac62c0865b3781e236
Requested by: @nikic
>From 6b1ebaea68f1e2140c54cc2c4a271e2847451c08 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulki...@google.com>
Date: Mon, 7 Apr 2025 08:41:49 -0700
Subject: [PATCH] [fatlto] Add coroutine passes when using FatLTO with ThinLTO
(#134434)
When coroutines are used w/ both -ffat-lto-objects and -flto=thin,
the coroutine passes are not added to the optimization pipelines.
Ensure they are added before ModuleOptimization to generate a
working ELF object.
Fixes #134409.
(cherry picked from commit 268c065eab06b81a0d7256ac62c0865b3781e236)
---
clang/test/CodeGenCoroutines/pr134409.cpp | 43 +++++++++++++++++++++++
llvm/lib/Passes/PassBuilderPipelines.cpp | 13 +++++++
2 files changed, 56 insertions(+)
create mode 100644 clang/test/CodeGenCoroutines/pr134409.cpp
diff --git a/clang/test/CodeGenCoroutines/pr134409.cpp
b/clang/test/CodeGenCoroutines/pr134409.cpp
new file mode 100644
index 0000000000000..142962d44ede4
--- /dev/null
+++ b/clang/test/CodeGenCoroutines/pr134409.cpp
@@ -0,0 +1,43 @@
+// An end-to-end test to make sure coroutine passes are added for thinlto.
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++23
-ffat-lto-objects -flto=thin -emit-llvm %s -O3 -o - \
+// RUN: | FileCheck %s
+
+#include "Inputs/coroutine.h"
+
+class BasicCoroutine {
+public:
+ struct Promise {
+ BasicCoroutine get_return_object() { return BasicCoroutine {}; }
+
+ void unhandled_exception() noexcept { }
+
+ void return_void() noexcept { }
+
+ std::suspend_never initial_suspend() noexcept { return {}; }
+ std::suspend_never final_suspend() noexcept { return {}; }
+ };
+ using promise_type = Promise;
+};
+
+// COM: match the embedded module, so we don't match something in it by
accident.
+// CHECK: @llvm.embedded.object = {{.*}}
+// CHECK: @llvm.compiler.used = {{.*}}
+
+BasicCoroutine coro() {
+// CHECK: define {{.*}} void @_Z4corov() {{.*}} {
+// CHECK-NEXT: entry:
+// CHECK-NEXT: ret void
+// CHECK-NEXT: }
+ co_return;
+}
+
+int main() {
+// CHECK: define {{.*}} i32 @main() {{.*}} {
+// CHECK-NEXT: entry:
+// CHECK-NEXT: tail call void @_Z4corov()
+// CHECK-NEXT: ret i32 0
+// CHECK-NEXT: }
+ coro();
+}
+
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp
b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 17ff3bd37884b..d195619f32d0b 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -1660,6 +1660,19 @@
PassBuilder::buildFatLTODefaultPipeline(OptimizationLevel Level, bool ThinLTO,
if (ThinLTO && PGOOpt && PGOOpt->Action == PGOOptions::SampleUse)
MPM.addPass(buildThinLTODefaultPipeline(Level, /*ImportSummary=*/nullptr));
else {
+ // ModuleSimplification does not run the coroutine passes for
+ // ThinLTOPreLink, so we need the coroutine passes to run for ThinLTO
+ // builds, otherwise they will miscompile.
+ if (ThinLTO) {
+ // TODO: replace w/ buildCoroWrapper() when it takes phase and level into
+ // consideration.
+ CGSCCPassManager CGPM;
+ CGPM.addPass(CoroSplitPass(Level != OptimizationLevel::O0));
+ CGPM.addPass(CoroAnnotationElidePass());
+ MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(std::move(CGPM)));
+ MPM.addPass(CoroCleanupPass());
+ }
+
// otherwise, just use module optimization
MPM.addPass(
buildModuleOptimizationPipeline(Level, ThinOrFullLTOPhase::None));
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