diff --git a/gcc/combine.c b/gcc/combine.c index 619c897f8116..f355abc0600a 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -674,6 +674,9 @@ combine_instructions (f, nregs) total_successes += combine_successes; nonzero_sign_valid = 0; + + /* Make recognizer allow volatile MEMs again. */ + init_recog (); } /* Wipe the reg_last_xxx arrays in preparation for another pass. */ diff --git a/gcc/regmove.c b/gcc/regmove.c index 35ddf12d6f39..55dd3f352c3b 100644 --- a/gcc/regmove.c +++ b/gcc/regmove.c @@ -553,6 +553,11 @@ optimize_reg_copy_3 (insn, dest, src) || SET_DEST (set) != src_reg) return; + /* Be conserative: although this optimization is also valid for + volatile memory references, that could cause trouble in later passes. */ + if (MEM_VOLATILE_P (SET_SRC (set))) + return; + /* Do not use a SUBREG to truncate from one mode to another if truncation is not a nop. */ if (GET_MODE_BITSIZE (GET_MODE (src_reg)) <= GET_MODE_BITSIZE (GET_MODE (src))