[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 Andrew Pinski changed: What|Removed |Added CC||davidfromonline at gmail dot com --- Comment #9 from Andrew Pinski --- *** Bug 105768 has been marked as a duplicate of this bug. ***
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 Andrew Pinski changed: What|Removed |Added Target Milestone|--- |13.0 Resolution|--- |FIXED Status|NEW |RESOLVED --- Comment #8 from Andrew Pinski --- Fixed.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 --- Comment #7 from Gabriel Ravier --- I don't know if I've missed something obvious but this still appears to be fixed.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 --- Comment #6 from Gabriel Ravier --- Can confirm that this appears to be fixed.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 --- Comment #5 from CVS Commits --- The master branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:ab981aab92cbc71918fbaadcf6fa64bdb2b69be7 commit r13-1187-gab981aab92cbc71918fbaadcf6fa64bdb2b69be7 Author: Arjun Shankar Date: Tue Jun 21 12:12:11 2022 +0200 match.pd: Remove "+ 0x8000" in int comparisons [PR94899] Expressions of the form "X + CST < Y + CST" where: * CST is an unsigned integer constant with only the MSB set, and * X and Y's types have integer conversion ranks <= CST's can be simplified to "(signed) X < (signed) Y". This is because, assuming a 32-bit signed numbers, (unsigned) INT_MIN + 0x8000 is 0, and (unsigned) INT_MAX + 0x8000 is UINT_MAX. i.e. the result increases monotonically with signed input. This means: ((signed) X < (signed) Y) iff (X + 0x8000 < Y + 0x8000) gcc/ PR tree-optimization/94899 * match.pd (X + C < Y + C -> (signed) X < (signed) Y, if C is 0x8000): New simplification. gcc/testsuite/ * gcc.dg/pr94899.c: New test.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 rsandifo at gcc dot gnu.org changed: What|Removed |Added Keywords||easyhack Status|RESOLVED|NEW Last reconfirmed||2020-05-01 CC||rsandifo at gcc dot gnu.org Resolution|INVALID |--- Ever confirmed|0 |1 --- Comment #4 from rsandifo at gcc dot gnu.org --- Reopening because... (In reply to Andrew Pinski from comment #2) > This is invalid as 0x8000 is unsigned (C90/C++03) or long (C99/C++11) in > type. > Which means then overflow is not undefined but rather wrapping. It's unsigned int for C99/C++11 too (see the different handling of decimal-literals and other integer-literals in [lex.icon.type]). This means that the result of the addition is also unsigned, For the specific value of 0x8000, the transformation is monotonic, so the optimisation is valid and well-defined.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 --- Comment #3 from Andrew Pinski --- If I used (int)(0x8000) instead, I get the optimization which means GCC is correct.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #2 from Andrew Pinski --- /* X + Z < Y + Z is the same as X < Y when there is no overflow. */ (for op (lt le ge gt) (simplify (op (plus:c @0 @2) (plus:c @1 @2)) (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)) && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))) (op @0 @1 ... /* X - Z < Y - Z is the same as X < Y when there is no overflow. */ (for op (lt le ge gt) (simplify (op (minus @0 @2) (minus @1 @2)) (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)) && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))) (op @0 @1 This is invalid as 0x8000 is unsigned (C90/C++03) or long (C99/C++11) in type. Which means then overflow is not undefined but rather wrapping. THIS ALSO means clang is broken.
[Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899 --- Comment #1 from Andrew Pinski --- The problem is only with INT_MIN.
