From 2bc6986d01c982026bb990a0b021b08f132fff74 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 2 Jan 2018 19:14:43 +0000 Subject: [PATCH] Fix REG_ARGS_SIZE handling when pushing TLS addresses The new assert in add_args_size_note triggered for gcc.dg/tls/opt-3.c and others on m68k. This looks like a pre-existing bug: if we pushed a value that needs a call to something like __tls_get_addr, we ended up with two different REG_ARGS_SIZE notes on the same instruction. It seems to be OK for emit_single_push_insn to push something that needs a call to __tls_get_addr: /* We have to allow non-call_pop patterns for the case of emit_single_push_insn of a TLS address. */ if (GET_CODE (pat) != PARALLEL) return 0; so I think the bug is in the way this is handled rather than the fact that it occurs at all. If we're pushing a value X that needs a call C to calculate, we'll add REG_ARGS_SIZE notes to the pushes and pops for C as part of the call sequence. Then emit_single_push_insn calls fixup_args_size_notes on the whole push sequence (the calculation of X, including C, and the push of X itself). This is where the double notes came from. But emit_single_push_insn_1 adjusted stack_pointer_delta *before* the push, so the notes added for C were relative to the situation after the future push of X rather than before it. Presumably this didn't matter in practice because the note added second tended to trump the note added first. But code is allowed to walk REG_NOTES without having to disregard secondary notes. 2018-01-02 Richard Sandiford gcc/ * expr.c (fixup_args_size_notes): Check that any existing REG_ARGS_SIZE notes are correct, and don't try to re-add them. (emit_single_push_insn_1): Move stack_pointer_delta adjustment to... (emit_single_push_insn): ...here. From-SVN: r256105 --- gcc/ChangeLog | 7 +++++++ gcc/expr.c | 20 ++++++++++++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c6d87f41c3d..8784450d1a6 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2018-01-02 Richard Sandiford + + * expr.c (fixup_args_size_notes): Check that any existing + REG_ARGS_SIZE notes are correct, and don't try to re-add them. + (emit_single_push_insn_1): Move stack_pointer_delta adjustment to... + (emit_single_push_insn): ...here. + 2018-01-02 Richard Sandiford * rtl.h (CONST_VECTOR_ELT): Redefine to const_vector_elt. diff --git a/gcc/expr.c b/gcc/expr.c index a84c02f41a9..275199982e3 100644 --- a/gcc/expr.c +++ b/gcc/expr.c @@ -4090,6 +4090,14 @@ fixup_args_size_notes (rtx_insn *prev, rtx_insn *last, if (!NONDEBUG_INSN_P (insn)) continue; + /* We might have existing REG_ARGS_SIZE notes, e.g. when pushing + a call argument containing a TLS address that itself requires + a call to __tls_get_addr. The handling of stack_pointer_delta + in emit_single_push_insn is supposed to ensure that any such + notes are already correct. */ + rtx note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX); + gcc_assert (!note || known_eq (args_size, get_args_size (note))); + poly_int64 this_delta = find_args_size_adjust (insn); if (known_eq (this_delta, 0)) { @@ -4103,7 +4111,8 @@ fixup_args_size_notes (rtx_insn *prev, rtx_insn *last, if (known_eq (this_delta, HOST_WIDE_INT_MIN)) saw_unknown = true; - add_args_size_note (insn, args_size); + if (!note) + add_args_size_note (insn, args_size); if (STACK_GROWS_DOWNWARD) this_delta = -poly_uint64 (this_delta); @@ -4127,7 +4136,6 @@ emit_single_push_insn_1 (machine_mode mode, rtx x, tree type) rtx dest; enum insn_code icode; - stack_pointer_delta += PUSH_ROUNDING (GET_MODE_SIZE (mode)); /* If there is push pattern, use it. Otherwise try old way of throwing MEM representing push operation to move expander. */ icode = optab_handler (push_optab, mode); @@ -4214,6 +4222,14 @@ emit_single_push_insn (machine_mode mode, rtx x, tree type) emit_single_push_insn_1 (mode, x, type); + /* Adjust stack_pointer_delta to describe the situation after the push + we just performed. Note that we must do this after the push rather + than before the push in case calculating X needs pushes and pops of + its own (e.g. if calling __tls_get_addr). The REG_ARGS_SIZE notes + for such pushes and pops must not include the effect of the future + push of X. */ + stack_pointer_delta += PUSH_ROUNDING (GET_MODE_SIZE (mode)); + last = get_last_insn (); /* Notice the common case where we emitted exactly one insn. */ -- 2.30.2