Author: wmi Date: Fri Sep 8 10:07:32 2017 New Revision: 312801 URL: http://llvm.org/viewvc/llvm-project?rev=312801&view=rev Log: Use EmitPointerWithAlignment to get alignment information of the pointer used in atomic expr.
This is to fix PR34347. EmitAtomicExpr now only uses alignment information from Type, instead of Decl, so when the declaration of an atomic variable is marked to have the alignment equal as its size, EmitAtomicExpr doesn't know about it and will generate libcall instead of atomic op. The patch uses EmitPointerWithAlignment to get the precise alignment information. Differential Revision: https://reviews.llvm.org/D37310 Added: cfe/trunk/test/CodeGenCXX/atomic-align.cpp Modified: cfe/trunk/lib/CodeGen/CGAtomic.cpp Modified: cfe/trunk/lib/CodeGen/CGAtomic.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGAtomic.cpp?rev=312801&r1=312800&r2=312801&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGAtomic.cpp (original) +++ cfe/trunk/lib/CodeGen/CGAtomic.cpp Fri Sep 8 10:07:32 2017 @@ -745,19 +745,19 @@ RValue CodeGenFunction::EmitAtomicExpr(A QualType MemTy = AtomicTy; if (const AtomicType *AT = AtomicTy->getAs<AtomicType>()) MemTy = AT->getValueType(); - CharUnits sizeChars, alignChars; - std::tie(sizeChars, alignChars) = getContext().getTypeInfoInChars(AtomicTy); - uint64_t Size = sizeChars.getQuantity(); - unsigned MaxInlineWidthInBits = getTarget().getMaxAtomicInlineWidth(); - bool UseLibcall = (sizeChars != alignChars || - getContext().toBits(sizeChars) > MaxInlineWidthInBits); - llvm::Value *IsWeak = nullptr, *OrderFail = nullptr; Address Val1 = Address::invalid(); Address Val2 = Address::invalid(); Address Dest = Address::invalid(); - Address Ptr(EmitScalarExpr(E->getPtr()), alignChars); + Address Ptr = EmitPointerWithAlignment(E->getPtr()); + + CharUnits sizeChars, alignChars; + std::tie(sizeChars, alignChars) = getContext().getTypeInfoInChars(AtomicTy); + uint64_t Size = sizeChars.getQuantity(); + unsigned MaxInlineWidthInBits = getTarget().getMaxAtomicInlineWidth(); + bool UseLibcall = (sizeChars != Ptr.getAlignment() || + getContext().toBits(sizeChars) > MaxInlineWidthInBits); if (E->getOp() == AtomicExpr::AO__c11_atomic_init || E->getOp() == AtomicExpr::AO__opencl_atomic_init) { Added: cfe/trunk/test/CodeGenCXX/atomic-align.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/atomic-align.cpp?rev=312801&view=auto ============================================================================== --- cfe/trunk/test/CodeGenCXX/atomic-align.cpp (added) +++ cfe/trunk/test/CodeGenCXX/atomic-align.cpp Fri Sep 8 10:07:32 2017 @@ -0,0 +1,30 @@ +// RUN: %clang_cc1 %s -std=c++11 -emit-llvm -o - -triple=x86_64-linux-gnu | FileCheck %s + +struct AM { + int f1, f2; +}; +alignas(8) AM m; +AM load1() { + AM am; + // m is declared to align to 8bytes, so generate load atomic instead + // of libcall. + // CHECK-LABEL: @_Z5load1v + // CHECK: load atomic {{.*}} monotonic + __atomic_load(&m, &am, 0); + return am; +} + +struct BM { + int f1; + alignas(8) AM f2; +}; +BM bm; +AM load2() { + AM am; + // BM::f2 is declared to align to 8bytes, so generate load atomic instead + // of libcall. + // CHECK-LABEL: @_Z5load2v + // CHECK: load atomic {{.*}} monotonic + __atomic_load(&bm.f2, &am, 0); + return am; +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
