https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100323
Bug ID: 100323 Summary: #pragma and attribute optimize don't enable inlining Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- I expected the effect of the attribute and the #pragma on the calls to f() in both g() and h() to be to inline them. They aren't. With #pragma clang optimize on, Clang inlines the call in h(). If this should be the expected behavior in GCC it should be documented. $ cat a.c && gcc -O0 -S -Wall -fdump-tree-optimized=/dev/stdout a.c static int f (void) { return 0; } __attribute__ ((optimize (2))) int g (void) { return f (); } #pragma GCC optimize ("2") int h (void) { return f (); } ;; Function f (f, funcdef_no=0, decl_uid=1943, cgraph_uid=1, symbol_order=0) int f () { int D.1952; int _1; <bb 2> : _1 = 0; <bb 3> : <L0>: return _1; } ;; Function g (g, funcdef_no=1, decl_uid=1946, cgraph_uid=2, symbol_order=1) __attribute__((optimize (2))) int g () { int _3; <bb 2> [local count: 1073741824]: _3 = f (); [tail call] return _3; } ;; Function h (h, funcdef_no=2, decl_uid=1949, cgraph_uid=3, symbol_order=2) __attribute__((optimize ("2"))) int h () { int _3; <bb 2> [local count: 1073741824]: _3 = f (); [tail call] return _3; }