The following invalid code snippet triggers an ICE since GCC 3.0 (with the exception of GCC 3.4.4 - 3.4.6):
===================================== void foo(double d) { __asm__ ("" : "=u" (d)); } ===================================== bug.c: In function 'foo': bug.c:3: error: output regs must be grouped at top of stack bug.c:4: internal compiler error: in emit_swap_insn, at reg-stack.c:818 Please submit a full bug report, [etc.] -- Summary: [4.1/4.2/4.3 regression] ICE with invalid constraint in asm statement Product: gcc Version: 4.3.0 Status: UNCONFIRMED Keywords: ice-on-invalid-code, error-recovery, monitored Severity: normal Priority: P3 Component: middle-end AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: reichelt at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30848