Author: Richard Smith Date: 2021-10-14T20:55:51-07:00 New Revision: effbf0bdd039237542ac5e9afe1f23c9386010e2
URL: https://github.com/llvm/llvm-project/commit/effbf0bdd039237542ac5e9afe1f23c9386010e2 DIFF: https://github.com/llvm/llvm-project/commit/effbf0bdd039237542ac5e9afe1f23c9386010e2.diff LOG: PR52183: Don't emit code for a void-typed constant expression. This is unnecessary in general, and wrong when the expression invokes a consteval function. Added: Modified: clang/lib/CodeGen/CGExprConstant.cpp clang/lib/CodeGen/CGExprScalar.cpp clang/test/CodeGenCXX/cxx2a-consteval.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp index d9ecf57a9ab5..ff900ed077e6 100644 --- a/clang/lib/CodeGen/CGExprConstant.cpp +++ b/clang/lib/CodeGen/CGExprConstant.cpp @@ -1714,6 +1714,8 @@ llvm::Constant *ConstantEmitter::emitForMemory(CodeGenModule &CGM, llvm::Constant *ConstantEmitter::tryEmitPrivate(const Expr *E, QualType destType) { + assert(!destType->isVoidType() && "can't emit a void constant"); + Expr::EvalResult Result; bool Success = false; diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp index 866da292819f..ae9434f96529 100644 --- a/clang/lib/CodeGen/CGExprScalar.cpp +++ b/clang/lib/CodeGen/CGExprScalar.cpp @@ -419,6 +419,11 @@ class ScalarExprEmitter Value *VisitExpr(Expr *S); Value *VisitConstantExpr(ConstantExpr *E) { + // A constant expression of type 'void' generates no code and produces no + // value. + if (E->getType()->isVoidType()) + return nullptr; + if (Value *Result = ConstantEmitter(CGF).tryEmitConstantExpr(E)) { if (E->isGLValue()) return CGF.Builder.CreateLoad(Address( diff --git a/clang/test/CodeGenCXX/cxx2a-consteval.cpp b/clang/test/CodeGenCXX/cxx2a-consteval.cpp index 7edddde693ca..b10ac8fa6825 100644 --- a/clang/test/CodeGenCXX/cxx2a-consteval.cpp +++ b/clang/test/CodeGenCXX/cxx2a-consteval.cpp @@ -2,7 +2,8 @@ // RUN: %clang_cc1 -emit-llvm %s -std=c++2a -triple x86_64-unknown-linux-gnu -o %t.ll // RUN: FileCheck -check-prefix=EVAL -input-file=%t.ll %s // RUN: FileCheck -check-prefix=EVAL-STATIC -input-file=%t.ll %s -// RUN: %clang_cc1 -emit-llvm %s -std=c++2a -triple x86_64-unknown-linux-gnu -o - | FileCheck -check-prefix=EVAL-FN %s +// RUN: FileCheck -check-prefix=EVAL-FN -input-file=%t.ll %s +// // RUN: %clang_cc1 -emit-llvm %s -Dconsteval="" -std=c++2a -triple x86_64-unknown-linux-gnu -o %t.ll // RUN: FileCheck -check-prefix=EXPR -input-file=%t.ll %s @@ -243,3 +244,10 @@ consteval int test_UserConvOverload_helper_ceval(int a) { return a; } int test_UserConvOverload_ceval() { return test_UserConvOverload_helper_ceval(UserConv()); } + +consteval void void_test() {} +void void_call() { // EVAL-FN-LABEL: define {{.*}} @_Z9void_call + // EVAL-FN-NOT: call + void_test(); + // EVAL-FN: {{^}}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
