https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119311
Bug ID: 119311
Summary: musttail attribute ineffective at -O0 and -O1
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: bruno at clisp dot org
Target Milestone: ---
Created attachment 60778
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60778&action=edit
test case foo.c
The documentation https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html
says:
"If the compiler cannot generate a musttail tail call it will report an error."
But this is not what I see, with the attached program, on x86_64: At
optimization levels -O0 and -O1, non-tail calls are generated; no error is
reported.
How to reproduce:
Compile the attached foo.c with option -S.
Expected:
No "call gcd" instruction inside function 'gcd'.
Actual:
With -O0 and -O1: Two "call gcd" instructions inside function 'gcd'.
Seen with with GCC version 15.0.1 20250316 (from godbolt.org).
