https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64539
Bug ID: 64539 Summary: [5 regression] cprop_hardreg does not respect clobbers in C_I_F_U Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: vries at gcc dot gnu.org As discussed in PR64154 comment 2 and 3, the clobbers in CALL_INSN_FUNCTION_USAGE are in general not registered by copyprop_hardreg_forward_1. F.i. in this thumb1 call insn there's a clobber of the ip reg, that is ignored by cprop_hardreg: ... (call_insn 141 292 142 13 (parallel [ (call (mem:SI (symbol_ref:SI ("f2") [flags 0x3] <function_decl 0x7f8182689100 f2>) [0 f2 S4 A32]) (const_int 0 [0])) (use (const_int 0 [0])) (clobber (reg:SI 14 lr)) ]) /myssd/terguo01/toolchain-build/GCC32RM-424/src/gcc/gcc/testsuite/gcc.dg/vshift-3.c:119 770 {*call_insn} (expr_list:REG_CALL_DECL (symbol_ref:SI ("f2") [flags 0x3] <function_decl 0x7f8182689100 f2>) (expr_list:REG_EH_REGION (const_int 0 [0]) (nil))) (expr_list (clobber (reg:SI 12 ip)) (nil))) ... I can't rule out that this is a generic bug, so marking tentatively as 5.0 regression.