From e34495985e49545c468e664ee10bd0e66c7395bf Mon Sep 17 00:00:00 2001 From: Eric Botcazou Date: Fri, 8 May 2020 17:18:20 +0200 Subject: [PATCH] Fix uniqueness of address for aliased objects Two aliased objects must have distinct addresses, even if they have size zero, so we make sure to allocate at least one byte for them. * gcc-interface/decl.c (gnat_to_gnu_entity) : Force at least the unit size for an aliased object of a constrained nominal subtype whose size is variable. --- gcc/ada/ChangeLog | 6 ++++++ gcc/ada/gcc-interface/decl.c | 15 ++++++++++++--- gcc/testsuite/ChangeLog | 4 ++++ gcc/testsuite/gnat.dg/addr15.adb | 19 +++++++++++++++++++ 4 files changed, 41 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gnat.dg/addr15.adb diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog index 9644e018f3e..35d111401e2 100644 --- a/gcc/ada/ChangeLog +++ b/gcc/ada/ChangeLog @@ -1,3 +1,9 @@ +2020-05-08 Eric Botcazou + + * gcc-interface/decl.c (gnat_to_gnu_entity) : Force at + least the unit size for an aliased object of a constrained nominal + subtype whose size is variable. + 2020-05-08 Eric Botcazou * gcc-interface/decl.c (gnat_to_gnu_entity) : Deal diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c index a4053eec839..9c1acd9f23f 100644 --- a/gcc/ada/gcc-interface/decl.c +++ b/gcc/ada/gcc-interface/decl.c @@ -969,10 +969,19 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition) align = MINIMUM_ATOMIC_ALIGNMENT; #endif - /* Make a new type with the desired size and alignment, if needed. - But do not take into account alignment promotions to compute the - size of the object. */ + /* Do not take into account aliased adjustments or alignment promotions + to compute the size of the object. */ tree gnu_object_size = gnu_size ? gnu_size : TYPE_SIZE (gnu_type); + + /* If the object is aliased, of a constrained nominal subtype and its + size might be zero at run time, we force at least the unit size. */ + if (Is_Aliased (gnat_entity) + && !Is_Constr_Subt_For_UN_Aliased (gnat_type) + && Is_Array_Type (Underlying_Type (gnat_type)) + && !TREE_CONSTANT (gnu_object_size)) + gnu_size = size_binop (MAX_EXPR, gnu_object_size, bitsize_unit_node); + + /* Make a new type with the desired size and alignment, if needed. */ if (gnu_size || align > 0) { tree orig_type = gnu_type; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index adacf69b027..8dc87d3948d 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2020-05-08 Eric Botcazou + + * gnat.dg/addr15.adb: New test. + 2020-05-08 Richard Biener * gnat.dg/opt83.adb: New testcase. diff --git a/gcc/testsuite/gnat.dg/addr15.adb b/gcc/testsuite/gnat.dg/addr15.adb new file mode 100644 index 00000000000..bb79dff862f --- /dev/null +++ b/gcc/testsuite/gnat.dg/addr15.adb @@ -0,0 +1,19 @@ +-- { dg-do run } + +with System; use System; + +procedure Addr15 is + + function Get_Bound (Param : Integer) return Integer is (Param); + + type Alpha_Typ is array (1 .. Get_Bound (1)) of Integer; + type Beta_Typ is array (1 .. Get_Bound (0)) of Integer; + + Alpha : Alpha_Typ; + Beta : aliased Beta_Typ; + +begin + if Alpha'Address = Beta'Address then + raise Program_Error; + end if; +end; -- 2.30.2