Author: Benson Chu Date: 2021-08-26T16:49:54-05:00 New Revision: 7bd92f5911dc7ec54200d37552d364f87ad03dfb
URL: https://github.com/llvm/llvm-project/commit/7bd92f5911dc7ec54200d37552d364f87ad03dfb DIFF: https://github.com/llvm/llvm-project/commit/7bd92f5911dc7ec54200d37552d364f87ad03dfb.diff LOG: [AST] Pick last tentative definition as the acting definition Clang currently picks the second tentative definition when VarDecl::getActingDefinition is called. This can lead to attributes being dropped if they are attached to tentative definitions that appear after the second one. This is because VarDecl::getActingDefinition loops through VarDecl::redecls assuming that the last tentative definition is the last element in the iterator. However, it is the second element that would be the last tentative definition. This changeset modifies getActingDefinition to iterate through the declaration chain in reverse, so that it can immediately return when it encounters a tentative definition. Originally the unit test for this changeset did not have a -triple flag for the clang invocation, leading to this test being broken on MacOS, since Mach-O does not support the section attribute. Differential Revision: https://reviews.llvm.org/D99732 Added: clang/test/CodeGen/attr-tentative-definition.c Modified: clang/lib/AST/Decl.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp index aa9fba519642a..835e28c0bc9fc 100644 --- a/clang/lib/AST/Decl.cpp +++ b/clang/lib/AST/Decl.cpp @@ -2216,14 +2216,18 @@ VarDecl *VarDecl::getActingDefinition() { return nullptr; VarDecl *LastTentative = nullptr; - VarDecl *First = getFirstDecl(); - for (auto I : First->redecls()) { - Kind = I->isThisDeclarationADefinition(); + + // Loop through the declaration chain, starting with the most recent. + for (VarDecl *Decl = getMostRecentDecl(); Decl; + Decl = Decl->getPreviousDecl()) { + Kind = Decl->isThisDeclarationADefinition(); if (Kind == Definition) return nullptr; - if (Kind == TentativeDefinition) - LastTentative = I; + // Record the first (most recent) TentativeDefinition that is encountered. + if (Kind == TentativeDefinition && !LastTentative) + LastTentative = Decl; } + return LastTentative; } diff --git a/clang/test/CodeGen/attr-tentative-definition.c b/clang/test/CodeGen/attr-tentative-definition.c new file mode 100644 index 0000000000000..0c49894e9bbc0 --- /dev/null +++ b/clang/test/CodeGen/attr-tentative-definition.c @@ -0,0 +1,7 @@ +// RUN: %clang_cc1 -emit-llvm -triple x86_64-linux-unknown < %s | FileCheck %s + +char arr[10]; +char arr[10] __attribute__((section("datadata"))); +char arr[10] __attribute__((aligned(16))); + +// CHECK: @arr ={{.*}}section "datadata", align 16 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
