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Tue, 21 May 2024 00:30:58 -0700 (PDT) Received: from localhost.localdomain ([2001:861:3382:1a90:de37:8b1c:1f33:2610]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-41fccee9292sm453333645e9.37.2024.05.21.00.30.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 May 2024 00:30:57 -0700 (PDT) From: =?utf-8?q?Marc_Poulhi=C3=A8s?= To: gcc-patches@gcc.gnu.org Cc: Eric Botcazou Subject: [COMMITTED 13/31] ada: Remove useless trampolines caused by Unchecked_Conversion Date: Tue, 21 May 2024 09:30:16 +0200 Message-ID: <20240521073035.314024-13-poulhies@adacore.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240521073035.314024-1-poulhies@adacore.com> References: <20240521073035.314024-1-poulhies@adacore.com> MIME-Version: 1.0 X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org From: Eric Botcazou The partial solution implemented in Validate_Unchecked_Conversion to support unchecked conversions between addresses and pointers to subprograms, for the platforms where pointers to subprograms do not all have the same size, turns out to be counter-productive for others because it may cause the creation of useless trampolines, which in turn makes the stack executable. gcc/ada/ * sem_ch13.adb (Validate_Unchecked_Conversion): Restrict forcing the Can_Use_Internal_Rep flag to platforms that require unnesting. Tested on x86_64-pc-linux-gnu, committed on master. --- gcc/ada/sem_ch13.adb | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb index 59c80022c20..4cf6fc9a645 100644 --- a/gcc/ada/sem_ch13.adb +++ b/gcc/ada/sem_ch13.adb @@ -18132,20 +18132,23 @@ package body Sem_Ch13 is Set_No_Strict_Aliasing (Implementation_Base_Type (Target)); end if; - -- If the unchecked conversion is between Address and an access - -- subprogram type, show that we shouldn't use an internal - -- representation for the access subprogram type. + -- For code generators that do not support nested subprograms, if the + -- unchecked conversion is between Address and an access subprogram + -- type, show that we shouldn't use an internal representation for the + -- access subprogram type. - if Is_Access_Subprogram_Type (Target) - and then Is_Descendant_Of_Address (Source) - and then In_Same_Source_Unit (Target, N) - then - Set_Can_Use_Internal_Rep (Base_Type (Target), False); - elsif Is_Access_Subprogram_Type (Source) - and then Is_Descendant_Of_Address (Target) - and then In_Same_Source_Unit (Source, N) - then - Set_Can_Use_Internal_Rep (Base_Type (Source), False); + if Unnest_Subprogram_Mode then + if Is_Access_Subprogram_Type (Target) + and then Is_Descendant_Of_Address (Source) + and then In_Same_Source_Unit (Target, N) + then + Set_Can_Use_Internal_Rep (Base_Type (Target), False); + elsif Is_Access_Subprogram_Type (Source) + and then Is_Descendant_Of_Address (Target) + and then In_Same_Source_Unit (Source, N) + then + Set_Can_Use_Internal_Rep (Base_Type (Source), False); + end if; end if; -- Generate N_Validate_Unchecked_Conversion node for back end in case