Author: Reid Kleckner Date: 2020-09-24T16:29:47-07:00 New Revision: b8a50e920704436ddcbe0cc9d2020935d7e37095
URL: https://github.com/llvm/llvm-project/commit/b8a50e920704436ddcbe0cc9d2020935d7e37095 DIFF: https://github.com/llvm/llvm-project/commit/b8a50e920704436ddcbe0cc9d2020935d7e37095.diff LOG: [MS] Simplify rules for passing C++ records Regardless of the target architecture, we should always use the C rules (RAA_Default) for records that "canBePassedInRegisters". Those are trivially copyable things, and things marked with [[trivial_abi]]. This should be NFC, although it changes where the final decision about x86_32 overaligned records is made. The current x86_32 C rules say that overaligned things are passed indirectly, so there is no functional difference. Added: Modified: clang/lib/CodeGen/MicrosoftCXXABI.cpp clang/test/CodeGenCXX/inalloca-overaligned.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp index 4f725793cb94..5fcb892f7fb8 100644 --- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp @@ -816,16 +816,22 @@ class MicrosoftCXXABI : public CGCXXABI { CGCXXABI::RecordArgABI MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const { + // Use the default C calling convention rules for things that can be passed in + // registers, i.e. non-trivially copyable records or records marked with + // [[trivial_abi]]. + if (RD->canPassInRegisters()) + return RAA_Default; + switch (CGM.getTarget().getTriple().getArch()) { default: // FIXME: Implement for other architectures. return RAA_Default; case llvm::Triple::thumb: - // Use the simple Itanium rules for now. + // Pass things indirectly for now because it is simple. // FIXME: This is incompatible with MSVC for arguments with a dtor and no // copy ctor. - return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default; + return RAA_Indirect; case llvm::Triple::x86: { // If the argument has *required* alignment greater than four bytes, pass @@ -838,17 +844,12 @@ MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const { // If C++ prohibits us from making a copy, construct the arguments directly // into argument memory. - if (!RD->canPassInRegisters()) - return RAA_DirectInMemory; - - // Otherwise, construct the argument into a temporary and copy the bytes - // into the outgoing argument memory. - return RAA_Default; + return RAA_DirectInMemory; } case llvm::Triple::x86_64: case llvm::Triple::aarch64: - return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default; + return RAA_Indirect; } llvm_unreachable("invalid enum"); diff --git a/clang/test/CodeGenCXX/inalloca-overaligned.cpp b/clang/test/CodeGenCXX/inalloca-overaligned.cpp index 83eb4d1c61a4..60b9da4f0861 100644 --- a/clang/test/CodeGenCXX/inalloca-overaligned.cpp +++ b/clang/test/CodeGenCXX/inalloca-overaligned.cpp @@ -85,3 +85,27 @@ int pass_inalloca_both() { // CHECK: [[TMP:%[^ ]*]] = alloca %struct.Both, align 8 // CHECK: call x86_thiscallcc %struct.Both* @"??0Both@@QAE@XZ"(%struct.Both* [[TMP]]) // CHECK: call i32 @"?receive_inalloca_both@@Y{{.*}}"(<{ %struct.NonTrivial, %struct.Both* }>* inalloca %argmem) + +// Here we have a type that is: +// - overaligned +// - not trivially copyable +// - can be "passed in registers" due to [[trivial_abi]] +// Clang should pass it directly. +struct [[trivial_abi]] alignas(8) MyPtr { + MyPtr(); + MyPtr(const MyPtr &o); + ~MyPtr(); + int *ptr; +}; + +int receiveMyPtr(MyPtr o) { return *o.ptr; } + +// CHECK-LABEL: define dso_local i32 @"?receiveMyPtr@@Y{{.*}}" +// CHECK-SAME: (%struct.MyPtr* %o) + +int passMyPtr() { return receiveMyPtr(MyPtr()); } + +// CHECK-LABEL: define dso_local i32 @"?passMyPtr@@Y{{.*}}" +// CHECK: [[TMP:%[^ ]*]] = alloca %struct.MyPtr, align 8 +// CHECK: call x86_thiscallcc %struct.MyPtr* @"??0MyPtr@@QAE@XZ"(%struct.MyPtr* [[TMP]]) +// CHECK: call i32 @"?receiveMyPtr@@Y{{.*}}"(%struct.MyPtr* [[TMP]]) _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
