From: Ilya Leoshkevich Date: Wed, 13 Jan 2021 12:59:10 +0000 (+0100) Subject: lra: clear lra_insn_recog_data after simplifying a mem subreg X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6dc82826ba61b25855e5a79f4479d009395a7299;p=gcc.git lra: clear lra_insn_recog_data after simplifying a mem subreg Suppose we have: (insn (set (reg:FPRX2 70) (subreg:FPRX2 (reg/v:TF 63) 0))) where operand_loc[0] points to r70 and operand_loc[1] points to r63. If r63 is spilled, remove_pseudos() will change this insn to: (insn (set (reg:FPRX2 70) (subreg:FPRX2 (mem/c:TF (plus:DI (reg:DI %fp) (const_int 144)))))) This is fine so far: rtx pointed to by operand_loc[1] has been changed from (reg) to (mem), but its slot is still under (subreg). However, alter_subreg() will simplify this insn to: (insn (set (reg:FPRX2 70) (mem/c:FPRX2 (plus:DI (reg:DI %fp) (const_int 144))))) The (subreg) is gone, and therefore operand_loc[1] is no longer valid. This will prevent process_insn_for_elimination() from updating the spill slot offset, causing miscompilation: different instructions will refer to the same spill slot using different offsets. Fix by clearing all the cached data, and not just used_insn_alternative. gcc/ChangeLog: 2021-01-13 Ilya Leoshkevich * lra-spills.c (remove_pseudos): Call lra_update_insn_recog_data() after calling alter_subreg() on a (mem). --- diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c index 26f56b2df02..01bd82574e7 100644 --- a/gcc/lra-spills.c +++ b/gcc/lra-spills.c @@ -431,7 +431,7 @@ remove_pseudos (rtx *loc, rtx_insn *insn) alter_subreg (loc, false); if (GET_CODE (*loc) == MEM) { - lra_get_insn_recog_data (insn)->used_insn_alternative = -1; + lra_update_insn_recog_data (insn); if (lra_dump_file != NULL) fprintf (lra_dump_file, "Memory subreg was simplified in insn #%u\n",