https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> --- It's combine combining 120 into 123 and on the way via propagate_for_debug replacing reg:SI 126 with the asm in the debug_insn. (insn 120 119 122 15 (parallel [ (set (reg:SI 126 [ resultvar ]) (asm_operands/v:SI ("xchgl %%ebx, %%edi int $0x80 xchgl %%edi, %%ebx ... (debug_insn 122 120 123 15 (var_location:SI resultvar (reg:SI 126 [ resultvar ])) bug-887141_pthread_create.1.min.i:77 -1 (nil)) (insn 123 122 124 15 (set (reg/v:SI 84 [ result ]) (reg:SI 126 [ resultvar ])) bug-887141_pthread_create.1.min.i:77 90 {*movsi_internal} (expr_list:REG_DEAD (reg:SI 126 [ resultvar ]) (nil))) So to avoid generating debug-insns with asm_operands loc maybe do Index: valtrack.c =================================================================== --- valtrack.c (revision 212580) +++ valtrack.c (working copy) @@ -197,6 +197,12 @@ propagate_for_debug (rtx insn, rtx last, next = NEXT_INSN (insn); if (DEBUG_INSN_P (insn)) { + if (GET_CODE (src) == ASM_OPERANDS) + { + INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); + df_insn_rescan (insn); + continue; + } loc = simplify_replace_fn_rtx (INSN_VAR_LOCATION_LOC (insn), dest, propagate_for_debug_subst, &p); if (loc == INSN_VAR_LOCATION_LOC (insn)) which "fixes" the bug.