From a6d31e8499c5bb691feef26f3a5e6562129eec42 Mon Sep 17 00:00:00 2001 From: Nathan Sidwell Date: Wed, 7 Jun 2017 13:41:20 +0000 Subject: [PATCH] class.c (layout_class_type): Restructure overlong-bitfield tpe search. * class.c (layout_class_type): Restructure overlong-bitfield tpe search. From-SVN: r248971 --- gcc/cp/ChangeLog | 5 ++++ gcc/cp/class.c | 60 +++++++++++++++++++++++------------------------- 2 files changed, 34 insertions(+), 31 deletions(-) diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index e47c4299748..8f377406baa 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,8 @@ +2017-06-07 Nathan Sidwell + + * class.c (layout_class_type): Restructure overlong-bitfield tpe + search. + 2017-06-07 Jonathan Wakely PR c++/80990 diff --git a/gcc/cp/class.c b/gcc/cp/class.c index 96377cc79ae..227466ec913 100644 --- a/gcc/cp/class.c +++ b/gcc/cp/class.c @@ -6426,41 +6426,39 @@ layout_class_type (tree t, tree *virtuals_p) if (DECL_C_BIT_FIELD (field) && tree_int_cst_lt (TYPE_SIZE (type), DECL_SIZE (field))) { - unsigned int itk; - tree integer_type; bool was_unnamed_p = false; /* We must allocate the bits as if suitably aligned for the - longest integer type that fits in this many bits. type - of the field. Then, we are supposed to use the left over - bits as additional padding. */ - for (itk = itk_char; itk != itk_none; ++itk) - if (integer_types[itk] != NULL_TREE - && (tree_int_cst_lt (size_int (MAX_FIXED_MODE_SIZE), - TYPE_SIZE (integer_types[itk])) - || tree_int_cst_lt (DECL_SIZE (field), - TYPE_SIZE (integer_types[itk])))) - break; - - /* ITK now indicates a type that is too large for the - field. We have to back up by one to find the largest - type that fits. */ - do - { - --itk; - integer_type = integer_types[itk]; - } while (itk > 0 && integer_type == NULL_TREE); + longest integer type that fits in this many bits. Then, + we are supposed to use the left over bits as additional + padding. */ + + /* Do not pick a type bigger than MAX_FIXED_MODE_SIZE. */ + tree limit = size_int (MAX_FIXED_MODE_SIZE); + if (tree_int_cst_lt (DECL_SIZE (field), limit)) + limit = DECL_SIZE (field); + + tree integer_type = integer_types[itk_char]; + for (unsigned itk = itk_char; itk != itk_none; itk++) + if (tree next = integer_types[itk]) + { + if (tree_int_cst_lt (limit, TYPE_SIZE (next))) + /* Too big, so our current guess is what we want. */ + break; + /* Not bigger than limit, ok */ + integer_type = next; + } /* Figure out how much additional padding is required. */ - if (tree_int_cst_lt (TYPE_SIZE (integer_type), DECL_SIZE (field))) - { - if (TREE_CODE (t) == UNION_TYPE) - /* In a union, the padding field must have the full width - of the bit-field; all fields start at offset zero. */ - padding = DECL_SIZE (field); - else - padding = size_binop (MINUS_EXPR, DECL_SIZE (field), - TYPE_SIZE (integer_type)); - } + if (TREE_CODE (t) == UNION_TYPE) + /* In a union, the padding field must have the full width + of the bit-field; all fields start at offset zero. */ + padding = DECL_SIZE (field); + else + padding = size_binop (MINUS_EXPR, DECL_SIZE (field), + TYPE_SIZE (integer_type)); + + if (integer_zerop (padding)) + padding = NULL_TREE; /* An unnamed bitfield does not normally affect the alignment of the containing class on a target where -- 2.30.2