[Pipelines] Do not run CoroSplit and CoroCleanup in LTO pre-link pipeline (#90310)

apolloww · web-flow · commit cd68d7b3c0eb · 2024-04-29T10:24:53.000-07:00
Skip CoroSplit and CoroCleanup in LTO pre-link pipeline so that
CoroElide can happen after callee coroutine is imported into caller's
module in ThinLTO.
diff --git a/clang/test/CodeGenCoroutines/coro-elide-thinlto.cpp b/clang/test/CodeGenCoroutines/coro-elide-thinlto.cpp
@@ -0,0 +1,77 @@
+// This tests that the coroutine elide optimization could happen succesfully with ThinLTO.
+// This test is adapted from coro-elide.cpp and splits functions into two files.
+//
+// RUN: split-file %s %t
+// RUN: %clang --target=x86_64-linux -std=c++20 -O2 -flto=thin -I %S -c %t/coro-elide-callee.cpp -o coro-elide-callee.o
+// RUN: %clang --target=x86_64-linux -std=c++20 -O2 -flto=thin -I %S -c %t/coro-elide-caller.cpp -o coro-elide-caller.o
+// RUN: llvm-lto -thinlto coro-elide-callee.o coro-elide-caller.o -o summary
+// RUN: %clang_cc1 -O2 -x ir coro-elide-caller.o -fthinlto-index=summary.thinlto.bc -emit-llvm -o - | FileCheck %s
+
+//--- coro-elide-task.h
+#pragma once
+#include "Inputs/coroutine.h"
+
+struct Task {
+  struct promise_type {
+    struct FinalAwaiter {
+      bool await_ready() const noexcept { return false; }
+      template <typename PromiseType>
+      std::coroutine_handle<> await_suspend(std::coroutine_handle<PromiseType> h) noexcept {
+        if (!h)
+          return std::noop_coroutine();
+        return h.promise().continuation;
+      }
+      void await_resume() noexcept {}
+    };
+    Task get_return_object() noexcept {
+      return std::coroutine_handle<promise_type>::from_promise(*this);
+    }
+    std::suspend_always initial_suspend() noexcept { return {}; }
+    FinalAwaiter final_suspend() noexcept { return {}; }
+    void unhandled_exception() noexcept {}
+    void return_value(int x) noexcept {
+      _value = x;
+    }
+    std::coroutine_handle<> continuation;
+    int _value;
+  };
+
+  Task(std::coroutine_handle<promise_type> handle) : handle(handle) {}
+  ~Task() {
+    if (handle)
+      handle.destroy();
+  }
+
+  struct Awaiter {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(std::coroutine_handle<void> continuation) noexcept {}
+    int await_resume() noexcept {
+      return 43;
+    }
+  };
+
+  auto operator co_await() {
+    return Awaiter{};
+  }
+
+private:
+  std::coroutine_handle<promise_type> handle;
+};
+
+//--- coro-elide-callee.cpp
+#include "coro-elide-task.h"
+Task task0() {
+  co_return 43;
+}
+
+//--- coro-elide-caller.cpp
+#include "coro-elide-task.h"
+
+Task task0();
+
+Task task1() {
+  co_return co_await task0();
+}
+
+// CHECK-LABEL: define{{.*}} void @_Z5task1v.resume
+// CHECK-NOT: {{.*}}_Znwm
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -963,7 +963,8 @@ PassBuilder::buildInlinerPipeline(OptimizationLevel Level,
   MainCGPipeline.addPass(createCGSCCToFunctionPassAdaptor(
       RequireAnalysisPass<ShouldNotRunFunctionPassesAnalysis, Function>()));
 
-  MainCGPipeline.addPass(CoroSplitPass(Level != OptimizationLevel::O0));
+  if (!isLTOPreLink(Phase))
+    MainCGPipeline.addPass(CoroSplitPass(Level != OptimizationLevel::O0));
 
   // Make sure we don't affect potential future NoRerun CGSCC adaptors.
   MIWP.addLateModulePass(createModuleToFunctionPassAdaptor(
@@ -1005,8 +1006,9 @@ PassBuilder::buildModuleInlinerPipeline(OptimizationLevel Level,
       buildFunctionSimplificationPipeline(Level, Phase),
       PTO.EagerlyInvalidateAnalyses));
 
-  MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(
-      CoroSplitPass(Level != OptimizationLevel::O0)));
+  if (!isLTOPreLink(Phase))
+    MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(
+        CoroSplitPass(Level != OptimizationLevel::O0)));
 
   return MPM;
 }
@@ -1183,7 +1185,8 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
   // and argument promotion.
   MPM.addPass(DeadArgumentEliminationPass());
 
-  MPM.addPass(CoroCleanupPass());
+  if (!isLTOPreLink(Phase))
+    MPM.addPass(CoroCleanupPass());
 
   // Optimize globals now that functions are fully simplified.
   MPM.addPass(GlobalOptPass());
diff --git a/llvm/test/Other/new-pm-defaults.ll b/llvm/test/Other/new-pm-defaults.ll
@@ -224,12 +224,14 @@
 ; CHECK-O-NEXT: Running pass: PostOrderFunctionAttrsPass
 ; CHECK-O-NEXT: Running pass: RequireAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Running analysis: ShouldNotRunFunctionPassesAnalysis
-; CHECK-O-NEXT: Running pass: CoroSplitPass
+; CHECK-DEFAULT-NEXT: Running pass: CoroSplitPass
+; CHECK-LTO-NOT: Running pass: CoroSplitPass
 ; CHECK-O-NEXT: Running pass: InvalidateAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: InlineAdvisorAnalysis
 ; CHECK-O-NEXT: Running pass: DeadArgumentEliminationPass
-; CHECK-O-NEXT: Running pass: CoroCleanupPass
+; CHECK-DEFAULT-NEXT: Running pass: CoroCleanupPass
+; CHECK-LTO-NOT: Running pass: CoroCleanupPass
 ; CHECK-O-NEXT: Running pass: GlobalOptPass
 ; CHECK-O-NEXT: Running pass: GlobalDCEPass
 ; CHECK-DEFAULT-NEXT: Running pass: EliminateAvailableExternallyPass
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-defaults.ll
@@ -183,12 +183,10 @@
 ; CHECK-O-NEXT: Running pass: PostOrderFunctionAttrsPass
 ; CHECK-O-NEXT: Running pass: RequireAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Running analysis: ShouldNotRunFunctionPassesAnalysis
-; CHECK-O-NEXT: Running pass: CoroSplitPass
 ; CHECK-O-NEXT: Running pass: InvalidateAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: InlineAdvisorAnalysis
 ; CHECK-O-NEXT: Running pass: DeadArgumentEliminationPass
-; CHECK-O-NEXT: Running pass: CoroCleanupPass
 ; CHECK-O-NEXT: Running pass: GlobalOptPass
 ; CHECK-O-NEXT: Running pass: GlobalDCEPass
 ; CHECK-EXT: Running pass: {{.*}}::Bye
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
@@ -182,12 +182,10 @@
 ; CHECK-O-NEXT: Running pass: PostOrderFunctionAttrsPass
 ; CHECK-O-NEXT: Running pass: RequireAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Running analysis: ShouldNotRunFunctionPassesAnalysis
-; CHECK-O-NEXT: Running pass: CoroSplitPass
 ; CHECK-O-NEXT: Running pass: InvalidateAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: InlineAdvisorAnalysis
 ; CHECK-O-NEXT: Running pass: DeadArgumentEliminationPass
-; CHECK-O-NEXT: Running pass: CoroCleanupPass
 ; CHECK-O-NEXT: Running pass: GlobalOptPass
 ; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis on bar
 ; CHECK-O-NEXT: Running pass: GlobalDCEPass
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
@@ -147,12 +147,10 @@
 ; CHECK-O-NEXT: Running pass: PostOrderFunctionAttrsPass
 ; CHECK-O-NEXT: Running pass: RequireAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Running analysis: ShouldNotRunFunctionPassesAnalysis
-; CHECK-O-NEXT: Running pass: CoroSplitPass
 ; CHECK-O-NEXT: Running pass: InvalidateAnalysisPass<{{.*}}ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: ShouldNotRunFunctionPassesAnalysis
 ; CHECK-O-NEXT: Invalidating analysis: InlineAdvisorAnalysis
 ; CHECK-O-NEXT: Running pass: DeadArgumentEliminationPass
-; CHECK-O-NEXT: Running pass: CoroCleanupPass
 ; CHECK-O-NEXT: Running pass: GlobalOptPass
 ; CHECK-O-NEXT: Running pass: GlobalDCEPass
 ; CHECK-O-NEXT: Running pass: AnnotationRemarksPass on foo
