diff options
Diffstat (limited to 'gcc/expr.c')
| -rw-r--r-- | gcc/expr.c | 42 |
1 files changed, 37 insertions, 5 deletions
diff --git a/gcc/expr.c b/gcc/expr.c index fa3d10ea2d7..c31eba65542 100644 --- a/gcc/expr.c +++ b/gcc/expr.c @@ -5021,14 +5021,27 @@ store_constructor (exp, target, cleared, size) { rtx xtarget = target; - if (readonly_fields_p (type)) + if (RTX_UNCHANGING_P (target)) { - xtarget = copy_rtx (xtarget); - RTX_UNCHANGING_P (xtarget) = 1; + xtarget = copy_rtx (target); + RTX_UNCHANGING_P (xtarget) = 0; } clear_storage (xtarget, GEN_INT (size)); cleared = 1; + if (RTX_UNCHANGING_P (target) || readonly_fields_p (type)) + { + /* ??? Emit a blockage to prevent the scheduler from swapping + the memory write issued above without the /u flag and + memory writes that will be issued later with it. + Note that the clearing above cannot be simply disabled + in the unsafe cases because the C front-end relies on + it to implement the semantics of constructors for + automatic objects. However, not all machine descriptions + define a blockage insn, so emit an ASM_INPUT to + act as one. */ + emit_insn (gen_rtx_ASM_INPUT (VOIDmode, "")); + } } if (! cleared) @@ -5242,9 +5255,28 @@ store_constructor (exp, target, cleared, size) if (! cleared) { if (REG_P (target)) - emit_move_insn (target, CONST0_RTX (GET_MODE (target))); + emit_move_insn (target, CONST0_RTX (GET_MODE (target))); else - clear_storage (target, GEN_INT (size)); + { + rtx xtarget = target; + + if (RTX_UNCHANGING_P (target)) + { + xtarget = copy_rtx (target); + RTX_UNCHANGING_P (xtarget) = 0; + } + + clear_storage (xtarget, GEN_INT (size)); + + if (RTX_UNCHANGING_P (target)) + { + /* ??? Emit a blockage to prevent the scheduler from + swapping the memory write issued above without the + /u flag and memory writes that will be issued later + with it. */ + emit_insn (gen_rtx_ASM_INPUT (VOIDmode, "")); + } + } } cleared = 1; } |