From: jason Date: Mon, 3 May 2010 21:16:40 +0000 (+0000) Subject: PR c++/43680 X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=commitdiff_plain;h=bb9c1a09933d3b672bedb16747761d478245dddc PR c++/43680 gcc: * c.opt (-fstrict-enums): New. * doc/invoke.texi (C++ Dialect Options): Document -fstrict-enums. gcc/cp: * decl.c (finish_enum): Use the TYPE_MIN_VALUE and TYPE_MAX_VALUE from the selected underlying type unless -fstrict-enums. Set ENUM_UNDERLYING_TYPE to have the restricted range. * cvt.c (type_promotes_to): Use ENUM_UNDERLYING_TYPE. * class.c (check_bitfield_decl): Likewise. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@159006 138bc75d-0d04-0410-961f-82ee72b054a4 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index f7fffbd9a46..30f3ea13fd9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2010-04-26 Jason Merrill + + * c.opt (-fstrict-enums): New. + * doc/invoke.texi (C++ Dialect Options): Document -fstrict-enums. + 2010-05-03 David Ung James E. Wilson diff --git a/gcc/c.opt b/gcc/c.opt index 2e1933cd0d1..3ab29830886 100644 --- a/gcc/c.opt +++ b/gcc/c.opt @@ -783,6 +783,10 @@ fstats C++ ObjC++ Display statistics accumulated during compilation +fstrict-enums +C++ ObjC++ Optimization Var(flag_strict_enums) +Assume that values of enumeration type are always within the minimum range of that type + fstrict-prototype C++ ObjC++ diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 51559e8aee6..8175f146aa1 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,13 @@ +2010-05-03 Jason Merrill + + PR c++/42810 + PR c++/43680 + * decl.c (finish_enum): Use the TYPE_MIN_VALUE and TYPE_MAX_VALUE + from the selected underlying type unless -fstrict-enums. Set + ENUM_UNDERLYING_TYPE to have the restricted range. + * cvt.c (type_promotes_to): Use ENUM_UNDERLYING_TYPE. + * class.c (check_bitfield_decl): Likewise. + 2010-05-01 H.J. Lu PR c++/43951 diff --git a/gcc/cp/class.c b/gcc/cp/class.c index c640af4d5b6..87f8111f15f 100644 --- a/gcc/cp/class.c +++ b/gcc/cp/class.c @@ -2786,14 +2786,8 @@ check_bitfield_decl (tree field) && TREE_CODE (type) != BOOLEAN_TYPE) warning (0, "width of %q+D exceeds its type", field); else if (TREE_CODE (type) == ENUMERAL_TYPE - && (0 > compare_tree_int (w, - tree_int_cst_min_precision - (TYPE_MIN_VALUE (type), - TYPE_UNSIGNED (type))) - || 0 > compare_tree_int (w, - tree_int_cst_min_precision - (TYPE_MAX_VALUE (type), - TYPE_UNSIGNED (type))))) + && (0 > (compare_tree_int + (w, TYPE_PRECISION (ENUM_UNDERLYING_TYPE (type)))))) warning (0, "%q+D is too small to hold all values of %q#T", field, type); } diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c index 1f87c5f8c26..5be0b8d8f30 100644 --- a/gcc/cp/cvt.c +++ b/gcc/cp/cvt.c @@ -682,7 +682,8 @@ ocp_convert (tree type, tree expr, int convtype, int flags) the original value is within the range of the enumeration values. Otherwise, the resulting enumeration value is unspecified. */ - if (TREE_CODE (expr) == INTEGER_CST && !int_fits_type_p (expr, type)) + if (TREE_CODE (expr) == INTEGER_CST + && !int_fits_type_p (expr, ENUM_UNDERLYING_TYPE (type))) warning (OPT_Wconversion, "the result of the conversion is unspecified because " "%qE is outside the range of type %qT", @@ -1311,6 +1312,8 @@ type_promotes_to (tree type) int precision = MAX (TYPE_PRECISION (type), TYPE_PRECISION (integer_type_node)); tree totype = c_common_type_for_size (precision, 0); + if (TREE_CODE (type) == ENUMERAL_TYPE) + type = ENUM_UNDERLYING_TYPE (type); if (TYPE_UNSIGNED (type) && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype)) type = c_common_type_for_size (precision, 1); diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 346b7b43646..56362828717 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -11255,12 +11255,6 @@ finish_enum (tree enumtype) tree maxnode; tree value; tree t; - bool unsignedp; - bool use_short_enum; - int lowprec; - int highprec; - int precision; - unsigned int itk; tree underlying_type = NULL_TREE; bool fixed_underlying_type_p = ENUM_UNDERLYING_TYPE (enumtype) != NULL_TREE; @@ -11323,17 +11317,19 @@ finish_enum (tree enumtype) the enumeration had a single enumerator with value 0. */ minnode = maxnode = integer_zero_node; - /* Compute the number of bits require to represent all values of the - enumeration. We must do this before the type of MINNODE and - MAXNODE are transformed, since tree_int_cst_min_precision relies - on the TREE_TYPE of the value it is passed. */ - unsignedp = tree_int_cst_sgn (minnode) >= 0; - lowprec = tree_int_cst_min_precision (minnode, unsignedp); - highprec = tree_int_cst_min_precision (maxnode, unsignedp); - precision = MAX (lowprec, highprec); - if (!fixed_underlying_type_p) { + /* Compute the number of bits require to represent all values of the + enumeration. We must do this before the type of MINNODE and + MAXNODE are transformed, since tree_int_cst_min_precision relies + on the TREE_TYPE of the value it is passed. */ + bool unsignedp = tree_int_cst_sgn (minnode) >= 0; + int lowprec = tree_int_cst_min_precision (minnode, unsignedp); + int highprec = tree_int_cst_min_precision (maxnode, unsignedp); + int precision = MAX (lowprec, highprec); + unsigned int itk; + bool use_short_enum; + /* Determine the underlying type of the enumeration. [dcl.enum] @@ -11380,43 +11376,51 @@ finish_enum (tree enumtype) The value of sizeof() applied to an enumeration type, an object of an enumeration type, or an enumerator, is the value of sizeof() applied to the underlying type. */ + TYPE_MIN_VALUE (enumtype) = TYPE_MIN_VALUE (underlying_type); + TYPE_MAX_VALUE (enumtype) = TYPE_MAX_VALUE (underlying_type); TYPE_SIZE (enumtype) = TYPE_SIZE (underlying_type); TYPE_SIZE_UNIT (enumtype) = TYPE_SIZE_UNIT (underlying_type); SET_TYPE_MODE (enumtype, TYPE_MODE (underlying_type)); + TYPE_PRECISION (enumtype) = TYPE_PRECISION (underlying_type); TYPE_ALIGN (enumtype) = TYPE_ALIGN (underlying_type); TYPE_USER_ALIGN (enumtype) = TYPE_USER_ALIGN (underlying_type); TYPE_UNSIGNED (enumtype) = TYPE_UNSIGNED (underlying_type); - /* Set the underlying type of the enumeration type to the - computed enumeration type, restricted to the enumerator - values. */ + /* Compute the minimum and maximum values for the type. + + [dcl.enum] + + For an enumeration where emin is the smallest enumerator and emax + is the largest, the values of the enumeration are the values of the + underlying type in the range bmin to bmax, where bmin and bmax are, + respectively, the smallest and largest values of the smallest bit- + field that can store emin and emax. */ + + /* The middle-end currently assumes that types with TYPE_PRECISION + narrower than their underlying type are suitably zero or sign + extended to fill their mode. Similarly, it assumes that the front + end assures that a value of a particular type must be within + TYPE_MIN_VALUE and TYPE_MAX_VALUE. + + We used to set these fields based on bmin and bmax, but that led + to invalid assumptions like optimizing away bounds checking. So + now we just set the TYPE_PRECISION, TYPE_MIN_VALUE, and + TYPE_MAX_VALUE to the values for the mode above and only restrict + the ENUM_UNDERLYING_TYPE for the benefit of diagnostics. */ ENUM_UNDERLYING_TYPE (enumtype) = build_distinct_type_copy (underlying_type); - set_min_and_max_values_for_integral_type + TYPE_PRECISION (ENUM_UNDERLYING_TYPE (enumtype)) = precision; + set_min_and_max_values_for_integral_type (ENUM_UNDERLYING_TYPE (enumtype), precision, unsignedp); + + /* If -fstrict-enums, still constrain TYPE_MIN/MAX_VALUE. */ + if (flag_strict_enums) + set_min_and_max_values_for_integral_type (enumtype, precision, + unsignedp); } else underlying_type = ENUM_UNDERLYING_TYPE (enumtype); - /* Compute the minimum and maximum values for the type. - - [dcl.enum] - - For an enumeration where emin is the smallest enumerator and emax - is the largest, the values of the enumeration are the values of the - underlying type in the range bmin to bmax, where bmin and bmax are, - respectively, the smallest and largest values of the smallest bit- - field that can store emin and emax. */ - - /* The middle-end currently assumes that types with TYPE_PRECISION - narrower than their underlying type are suitably zero or sign - extended to fill their mode. g++ doesn't make these guarantees. - Until the middle-end can represent such paradoxical types, we - set the TYPE_PRECISION to the width of the underlying type. */ - TYPE_PRECISION (enumtype) = TYPE_PRECISION (underlying_type); - - set_min_and_max_values_for_integral_type (enumtype, precision, unsignedp); - /* Convert each of the enumerators to the type of the underlying type of the enumeration. */ for (values = TYPE_VALUES (enumtype); values; values = TREE_CHAIN (values)) diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index fefb0abd1d5..b2fbd48becd 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -1982,6 +1982,15 @@ unambiguous base classes. Emit statistics about front-end processing at the end of the compilation. This information is generally only useful to the G++ development team. +@item -fstrict-enums +@opindex fstrict-enums +Allow the compiler to optimize using the assumption that a value of +enumeration type can only be one of the values of the enumeration (as +defined in the C++ standard; basically, a value which can be +represented in the minimum number of bits needed to represent all the +enumerators). This assumption may not be valid if the program uses a +cast to convert an arbitrary integer value to the enumeration type. + @item -ftemplate-depth=@var{n} @opindex ftemplate-depth Set the maximum instantiation depth for template classes to @var{n}. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 1f7fe55be57..722ee1e46a9 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2010-05-03 Jason Merrill + + PR c++/43680 + * g++.dg/opt/enum2.C: New. + * g++.dg/warn/pr33738.C: Use -fstrict-enums. + * g++.dg/warn/Wswitch-1.C: Adjust message. + 2010-05-03 Rainer Orth * g++.dg/cdce3.C: Skip on alpha*-dec-osf5*. diff --git a/gcc/testsuite/g++.dg/opt/enum2.C b/gcc/testsuite/g++.dg/opt/enum2.C new file mode 100644 index 00000000000..6300896cff9 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/enum2.C @@ -0,0 +1,21 @@ +// PR c++/43680 +// Test that we don't make excessively aggressive assumptions about what +// values an enum variable can have. +// { dg-options "-O2 -fPIC" } +// { dg-do run } + +extern "C" void abort (); + +enum E { A, B, C, D }; + +void +CheckE(const E value) +{ + long v = value; + if (v <= D) + abort (); +} + +int main() { + CheckE(static_cast(5)); +} diff --git a/gcc/testsuite/g++.dg/warn/Wswitch-1.C b/gcc/testsuite/g++.dg/warn/Wswitch-1.C index 6a2094466cf..1da7180ec79 100644 --- a/gcc/testsuite/g++.dg/warn/Wswitch-1.C +++ b/gcc/testsuite/g++.dg/warn/Wswitch-1.C @@ -50,13 +50,13 @@ foo (int i, int j, enum e ei, enum e ej, enum e ek, enum e el, { case e1: return 1; case e2: return 2; - case 3: return 3; /* { dg-warning "exceeds maximum value" } */ + case 3: return 3; /* { dg-warning "case value" } */ } switch (ep) { case e1: return 1; case e2: return 2; - case 3: return 3; /* { dg-warning "exceeds maximum value" } */ + case 3: return 3; /* { dg-warning "case value" } */ default: break; } return 0; diff --git a/gcc/testsuite/g++.dg/warn/pr33738.C b/gcc/testsuite/g++.dg/warn/pr33738.C index 8847b6e342c..e84fece13f6 100644 --- a/gcc/testsuite/g++.dg/warn/pr33738.C +++ b/gcc/testsuite/g++.dg/warn/pr33738.C @@ -1,5 +1,5 @@ // { dg-do run } -// { dg-options "-O2 -Wtype-limits" } +// { dg-options "-O2 -Wtype-limits -fstrict-enums" } extern void link_error (void); enum Alpha {