https://github.com/zyn0217 created https://github.com/llvm/llvm-project/pull/124572
This is taken from https://github.com/llvm/llvm-project/pull/122423#discussion_r1930102632 as suggested by Corentin. Fixes #82926 >From f515e670d35365f14f063e02eb10cd41e3751937 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Mon, 27 Jan 2025 23:42:22 +0800 Subject: [PATCH] [Clang] Skip past code generation for unevaluated lambdas As suggested by Corentin, this is taken from https://github.com/llvm/llvm-project/pull/122423#discussion_r1930102632 --- clang/docs/ReleaseNotes.rst | 1 + .../lib/Sema/SemaTemplateInstantiateDecl.cpp | 20 +++++++++- clang/test/CodeGenCXX/unevaluated-lambdas.cpp | 37 +++++++++++++++++++ 3 files changed, 56 insertions(+), 2 deletions(-) create mode 100644 clang/test/CodeGenCXX/unevaluated-lambdas.cpp diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index f75c726e2751cf..7bb33d6b44d4ee 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -966,6 +966,7 @@ Bug Fixes to C++ Support constraints are applied. (#GH122134) - Fixed canonicalization of pack indexing types - Clang did not always recognized identical pack indexing. (#GH123033) - Fixed a nested lambda substitution issue for constraint evaluation. (#GH123441) +- Fixed some crashes involving unevaluated lambdas during code generation. (#GH82926) Bug Fixes to AST Handling diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 6a2331e59477a2..6a55dbd98b0b4d 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -5297,8 +5297,24 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, savedContext.pop(); } - DeclGroupRef DG(Function); - Consumer.HandleTopLevelDecl(DG); + // We never need to emit the code for a lambda in unevaluated context. + // We also can't mangle a lambda in the require clause of a function template + // during constraint checking as the MSI ABI would need to mangle the (not yet + // specialized) enclosing declaration + // FIXME: Should we try to skip this for non-lambda functions too? + bool ShouldSkipCG = [&] { + auto *RD = dyn_cast<CXXRecordDecl>(Function->getParent()); + if (!RD || !RD->isLambda()) + return false; + + return llvm::any_of(ExprEvalContexts, [](auto &Context) { + return Context.isUnevaluated() || Context.isImmediateFunctionContext(); + }); + }(); + if (!ShouldSkipCG) { + DeclGroupRef DG(Function); + Consumer.HandleTopLevelDecl(DG); + } // This class may have local implicit instantiations that need to be // instantiation within this scope. diff --git a/clang/test/CodeGenCXX/unevaluated-lambdas.cpp b/clang/test/CodeGenCXX/unevaluated-lambdas.cpp new file mode 100644 index 00000000000000..5bdf8294dc1fc3 --- /dev/null +++ b/clang/test/CodeGenCXX/unevaluated-lambdas.cpp @@ -0,0 +1,37 @@ +// RUN: %clang_cc1 -std=c++2b -emit-llvm %s -o - | FileCheck %s -dump-input=always + +namespace GH82926 { + +template<class Tp> +using simd_vector = Tp; + +template<class VecT> +using simd_vector_underlying_type_t + = decltype([]<class Tp>(simd_vector<Tp>) {}(VecT {}), 1); + +template<class VecT> +void temp() { + // CHECK: call void @_ZZN7GH829264tempIcEEvvENKUliE_clEi + [](simd_vector_underlying_type_t<VecT>) {}(42); +} + +void call() { + temp<simd_vector<char>>(); +} + +} // namespace GH82926 + +namespace GH111058 { + +// FIXME: This still crashes because the unevaluated lambda as an argument +// is also supposed to skipping codegen in Sema::InstantiateFunctionDefinition(). +// auto eat(auto) {} + +void foo() { + // [] -> decltype(eat([] {})) {}; + + // CHECK: call void @"_ZZN8GH1110583fooEvENK3$_0clEv" + [] -> decltype([](auto){}(1)) {}(); +} + +} // namespace GH111058 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
