[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774 Jakub Jelinek changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #11 from Jakub Jelinek --- Fixed for 10.5 too.
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
--- Comment #10 from CVS Commits ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
:
https://gcc.gnu.org/g:11bf3345c74139c05c405d3e5bc73ee8d9e7d6a6
commit r10-11340-g11bf3345c74139c05c405d3e5bc73ee8d9e7d6a6
Author: Jakub Jelinek
Date: Mon Oct 24 16:25:29 2022 +0200
c++: Fix up constexpr handling of char/signed char/short pre/post
inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek
PR c++/105774
* constexpr.c (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
(cherry picked from commit da8c362c4c18cff2f2dfd5c4706bdda7576899a4)
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
--- Comment #9 from CVS Commits ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
:
https://gcc.gnu.org/g:11a37955860f8573570aaf8d9fb0b6e02a3d4d5a
commit r11-10362-g11a37955860f8573570aaf8d9fb0b6e02a3d4d5a
Author: Jakub Jelinek
Date: Mon Oct 24 16:25:29 2022 +0200
c++: Fix up constexpr handling of char/signed char/short pre/post
inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek
PR c++/105774
* constexpr.c (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
(cherry picked from commit da8c362c4c18cff2f2dfd5c4706bdda7576899a4)
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
--- Comment #8 from CVS Commits ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
:
https://gcc.gnu.org/g:20ef7d7c578dab0585d70fbea571a74e8e8d4b47
commit r12--g20ef7d7c578dab0585d70fbea571a74e8e8d4b47
Author: Jakub Jelinek
Date: Mon Oct 24 16:25:29 2022 +0200
c++: Fix up constexpr handling of char/signed char/short pre/post
inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek
PR c++/105774
* constexpr.cc (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
(cherry picked from commit da8c362c4c18cff2f2dfd5c4706bdda7576899a4)
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774 --- Comment #7 from Jakub Jelinek --- Fixed on the trunk so far.
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
--- Comment #6 from CVS Commits ---
The master branch has been updated by Jakub Jelinek :
https://gcc.gnu.org/g:da8c362c4c18cff2f2dfd5c4706bdda7576899a4
commit r13-3458-gda8c362c4c18cff2f2dfd5c4706bdda7576899a4
Author: Jakub Jelinek
Date: Mon Oct 24 16:25:29 2022 +0200
c++: Fix up constexpr handling of char/signed char/short pre/post
inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek
PR c++/105774
* constexpr.cc (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774 Jakub Jelinek changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org Status|NEW |ASSIGNED --- Comment #5 from Jakub Jelinek --- Created attachment 53763 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53763=edit gcc13-pr105774.patch Untested fix.
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
--- Comment #4 from Andrew Pinski ---
And one for short:
constexpr signed short f(void){
signed short x = 0x7fff;
return ++x;
}
int main() {
constexpr auto _ = f();
}
[Bug c++/105774] Bogus overflow in constant expression with signed char++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105774
Andrew Pinski changed:
What|Removed |Added
Summary|Bogus overflow in constant |Bogus overflow in constant
|expression with char++ |expression with signed
||char++
Known to fail||5.1.0
--- Comment #3 from Andrew Pinski ---
Here is a C++14 testcase (lambdas were not constexpr in C++14) which shows the
issue has been there since GCC 5 (which didn't have C++17 support):
constexpr signed char f(void){
signed char x = 127;
return ++x;
}
int main() {
constexpr auto _ = f();
}
