http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47028
Summary: [4.6 Regression] gcc.dg/tree-ssa/tailrecursion-[57].c FAIL with -foptimize-sibling-calls -fno-forward-propagate -fno-tree-copy-prop -fno-tree-dominator-opts Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization AssignedTo: unassig...@gcc.gnu.org ReportedBy: zso...@seznam.cz Host: x86_64-pc-linux-gnu Target: x86_64-pc-linux-gnu Created attachment 22832 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22832 reduced testcase Output: $ gcc -O -foptimize-sibling-calls -fno-forward-propagate -fno-tree-copy-prop -fno-tree-dominator-opts pr47028.c $ ./a.out Aborted At the assembly level, fib() is reduced to "return 1;": fib: mov eax, 0 # add_acc.0, add eax, 1 # tmp73, ret it seems to first appear in the pr47028.c.179r.combine dump Tested revision: r168061 - fail r165699 - fail r161659 - OK 4.5 r168062 -OK