https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122438
--- Comment #7 from Andreas Schwab <[email protected]> --- Difference between r15-2195-ga8e61cd71f0cda and r15-2196-g88d16194d0c8a6 in ext-dce dump: @@ -5,6 +5,15 @@ ending the processing of deferred insns df_analyze called df_worklist_dataflow_doublequeue: n_basic_blocks 8 n_edges 9 count 8 ( 1) +Processing insn: + 36: {r48:DI=sign_extend(r47:SI);clobber scratch;} + REG_DEAD r47:SI +Trying to simplify pattern: +(sign_extend:DI (reg:SI 47)) +rescanning insn with uid = 36. +Successfully transformed to: +(subreg:DI (reg:SI 47) 0) + df_worklist_dataflow_doublequeue: n_basic_blocks 8 n_edges 9 count 8 ( 1) starting the processing of deferred insns ending the processing of deferred insns @@ -136,11 +145,8 @@ (reg:SI 0 %d0)) "showdb-showdb.i":13:14 55 {*movsi_m68k2} (expr_list:REG_DEAD (reg:SI 0 %d0) (nil))) -(insn 36 34 37 6 (parallel [ - (set (reg:DI 48 [ _30 ]) - (sign_extend:DI (reg:SI 47))) - (clobber (scratch:SI)) - ]) "showdb-showdb.i":13:14 discrim 1 93 {extendsidi2} +(insn 36 34 37 6 (set (reg:DI 48 [ _30 ]) + (subreg:DI (reg:SI 47) 0)) "showdb-showdb.i":13:14 discrim 1 75 {*m68k> (expr_list:REG_DEAD (reg:SI 47) (nil))) (insn 37 36 42 6 (parallel [
