[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 Jason Merrill changed: What|Removed |Added Target Milestone|--- |12.0 Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #7 from Jason Merrill --- Fixed for GCC 12.
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 --- Comment #6 from CVS Commits --- The master branch has been updated by Jason Merrill : https://gcc.gnu.org/g:7232f7c4c2d727431096a7ecfcf4ad4db71dcf2a commit r12-1702-g7232f7c4c2d727431096a7ecfcf4ad4db71dcf2a Author: Jason Merrill Date: Sun Jun 13 14:00:12 2021 -0400 expand: empty class return optimization [PR88529] The x86_64 psABI says that an empty class isn't passed or returned in memory or registers, so we shouldn't set %eax in this function. The df-scan hunk catches the case where we look at a 0-length reg and build a range the length of unsigned int, which happened before I changed assign_parms to match expand_function_end. PR target/88529 gcc/ChangeLog: * df-scan.c (df_ref_record): Check that regno < endregno. * function.c (assign_parms, expand_function_end): Do nothing with a TYPE_EMPTY_P result. gcc/testsuite/ChangeLog: * g++.target/i386/empty-class1.C: New test.
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 Jason Merrill changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |jason at gcc dot gnu.org
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 --- Comment #5 from Antony Polukhin --- (In reply to Jason Merrill from comment #1) > Created attachment 45899 [details] > Fix Is it enough to test only for `scan-assembler-not mov`? Probably a `scan-assembler-not xor` should be also added?
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 --- Comment #4 from Andrew Pinski --- related to PR20408 (but not the same as the patch which Jason attached is different)
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2019-03-25 Ever confirmed|0 |1 Severity|normal |enhancement --- Comment #3 from Andrew Pinski --- There might be another bug that talks about this similar thing. Confirmed.
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 Andrew Pinski changed: What|Removed |Added CC||antoshkka at gmail dot com --- Comment #2 from Andrew Pinski --- *** Bug 89820 has been marked as a duplicate of this bug. ***
[Bug target/88529] G++ clears the return register on x86_64 when returning an empty class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88529 Jason Merrill changed: What|Removed |Added CC||jason at gcc dot gnu.org --- Comment #1 from Jason Merrill --- Created attachment 45899 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45899=edit Fix Here's a fix. I'm not sure if it's suitable for GCC 9 or 10.
