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Re: [PATCH] Sanitizing the middle-end interface to the back-end for strict alignment

Hi Bernd,

On 8/29/19 10:26 PM, Bernd Edlinger wrote:
On 8/29/19 11:08 AM, Christophe Lyon wrote:
On Thu, 29 Aug 2019 at 10:58, Kyrill Tkachov
<> wrote:
Hi Bernd,

On 8/28/19 10:36 PM, Bernd Edlinger wrote:
On 8/28/19 2:07 PM, Christophe Lyon wrote:

This patch causes an ICE when building libgcc's unwind-arm.o
when configuring GCC:
--target  arm-none-linux-gnueabihf --with-mode thumb --with-cpu
cortex-a15 --with-fpu neon-vfpv4:

The build works for the same target, but --with-mode arm --with-cpu
cortex a9 --with-fpu vfp

In file included from
In function 'get_eit_entry':
warning: cast discards 'const' qualifier from pointer target type
    245 |       ucbp->pr_cache.ehtp = (_Unwind_EHT_Header *)&eitp->content;
        |                             ^
during RTL pass: expand
In function 'unwind_phase2_forced':
internal compiler error: in gen_movdi, at config/arm/
    319 |   saved_vrs.core = entry_vrs->core;
        |   ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
0x126530f gen_movdi(rtx_def*, rtx_def*)
0x896d92 insn_gen_fn::operator()(rtx_def*, rtx_def*) const
0x896d92 emit_move_insn_1(rtx_def*, rtx_def*)
0x897083 emit_move_insn(rtx_def*, rtx_def*)
0xfc25d6 gen_cpymem_ldrd_strd(rtx_def**)
0x126a1f1 gen_cpymemqi(rtx_def*, rtx_def*, rtx_def*, rtx_def*)
0xb0bc08 maybe_expand_insn(insn_code, unsigned int, expand_operand*)
0x89ba1e emit_block_move_via_cpymem
0x89ba1e emit_block_move_hints(rtx_def*, rtx_def*, rtx_def*,
block_op_methods, unsigned int, long, unsigned long, unsigned long,
unsigned long, bool, bool*)
0x89c383 emit_block_move(rtx_def*, rtx_def*, rtx_def*, block_op_methods)
0x89fb4e store_expr(tree_node*, rtx_def*, int, bool, bool)
0x88c1f9 store_field
0x8a0c22 expand_assignment(tree_node*, tree_node*, bool)
0x761964 expand_gimple_stmt_1
0x761964 expand_gimple_stmt
0x768583 expand_gimple_basic_block
0x76abc6 execute


Okay, sorry for the breakage.

What is happening in gen_cpymem_ldrd_strd is of course against the rules:

It uses emit_move_insn on only 4-byte aligned DI-mode memory operands.

I have a patch for this, which is able to fix the libgcc build on a cross, but have no
possibility to bootstrap the affected target.

Could you please help?
Well it's good that the sanitisation is catching the bugs!

Yes, more than expected, though ;)

Bootstrapping this patch I get another assert with the backtrace:
Thanks for the additional testing, Kyrill!

FWIW, my original report was with a failure to just build GCC for
cortex-a15. I later got the reports of testing cross-toolchains, and
saw other problems on cortex-a9 for instance.
But I guess, you have noticed them with your bootstrap?
on arm-linux-gnueabi (internal compiler error) (internal compiler error)

This appears to be yet unknown middle-end bug (not fixed by current patch)

$ arm-linux-gnueabihf-gcc align4.c
during RTL pass: expand
In file included from align4.c:22:
align4.c: In function 'testfunc':
abitest.h:73:42: internal compiler error: in gen_movv2si, at config/arm/
    73 | #define LAST_ARG(type,val,offset) { type __x = val; if (memcmp(&__x, stack+offset, sizeof(type)) != 0) abort(); }
       |                                          ^~~
abitest.h:74:30: note: in expansion of macro 'LAST_ARG'
    74 | #define ARG(type,val,offset) LAST_ARG(type, val, offset)
       |                              ^~~~~~~~
align4.c:26:3: note: in expansion of macro 'ARG'
    26 |   ARG (unalignedvec, a, R2)
       |   ^~~
0x7bb33c gen_movv2si(rtx_def*, rtx_def*)
0xa4a807 insn_gen_fn::operator()(rtx_def*, rtx_def*) const
0xa4a807 emit_move_insn_1(rtx_def*, rtx_def*)
0xa4ab94 emit_move_insn(rtx_def*, rtx_def*)
0xa522bf store_expr(tree_node*, rtx_def*, int, bool, bool)
0xa52bfd expand_assignment(tree_node*, tree_node*, bool)
0xa52bfd expand_assignment(tree_node*, tree_node*, bool)
0x934adf expand_gimple_stmt_1
0x934adf expand_gimple_stmt
0x93a451 expand_gimple_basic_block
0x93c1b6 execute
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <> for instructions.

(with -march=armv5t: gcc.dg/pr83930.c (internal compiler error))

possibly fixed by latest patch.

on arm-linux-gnueabihf, in addition to align4/align_rec4:
--with-cpu cortex-a9
--with-fpu neon-fp16
     gcc.c-torture/execute/pr37573.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  (internal
compiler error)
     gcc.c-torture/execute/pr37573.c   -O3 -g  (internal compiler error)
     gcc.dg/vect/fast-math-pr35982.c (internal compiler error)
     gcc.dg/vect/pr55857-1.c (internal compiler error)
     gcc.dg/vect/pr55857-1.c -flto -ffat-lto-objects (internal compiler error)
     gcc.dg/vect/pr55857-2.c (internal compiler error)
     gcc.dg/vect/pr55857-2.c -flto -ffat-lto-objects (internal compiler error)
     gcc.dg/vect/pr57558-2.c (internal compiler error)
     gcc.dg/vect/pr57558-2.c -flto -ffat-lto-objects (internal compiler error)

and even more with other configs
may help)


In function '(static initializers for
internal compiler error: in gen_movv8qi, at config/arm/
    129 |     {
        |     ^
0x14155cb gen_movv8qi(rtx_def*, rtx_def*)
0x96bb89 insn_gen_fn::operator()(rtx_def*, rtx_def*) const
0x94bc95 emit_move_insn_1(rtx_def*, rtx_def*)
0x94c05b emit_move_insn(rtx_def*, rtx_def*)
0x10d5ee5 arm_block_set_aligned_vect
0x10d6b37 arm_block_set_vect
0x10d6caf arm_gen_setmem(rtx_def**)
0x140d7ed gen_setmemsi(rtx_def*, rtx_def*, rtx_def*, rtx_def*)
0xbf0e87 insn_gen_fn::operator()(rtx_def*, rtx_def*, rtx_def*, rtx_def*)
0xbf0999 maybe_gen_insn(insn_code, unsigned int, expand_operand*)
0xbf0b87 maybe_expand_insn(insn_code, unsigned int, expand_operand*)
0x94a709 set_storage_via_setmem(rtx_def*, rtx_def*, rtx_def*, unsigned
int, unsigned int, long long, unsigned long long, unsigned long long,
unsigned long long)
0x94a059 clear_storage_hints(rtx_def*, rtx_def*, block_op_methods,
unsigned int, long long, unsigned long long, unsigned long long,
unsigned long long)
0x94a137 clear_storage(rtx_def*, rtx_def*, block_op_methods)
0x9537c5 store_constructor
0x957227 store_field
0x94fde1 expand_assignment(tree_node*, tree_node*, bool)
0x815e25 expand_gimple_stmt_1
0x81611d expand_gimple_stmt
0x81cd61 expand_gimple_basic_block

Looks to me like arm_gen_setmem needs similar fixes to gen_cpymem_ldrd_strd?

Yes, indeed, see attached patch.

This seems to fix the bootstrap, but at least one other error remains,
however I think those do hopefully not break the boot-strap and can be
fixed with follow-up patches.

Christophe can you please track the remaining regressions, that would be
very helpful.

Attached is an updated patch version which should un-break the bootstrap issues.
Is it OK for trunk?

Yes, that fixes the bootstrap and testing looks ok, modulo the regressions Christophe listed.

Ok with one change...

+(define_insn "unaligned_storev8qi"
+  [(set (match_operand:V8QI 0 "memory_operand" "=Un")
+	(unspec:V8QI [(match_operand:V8QI 1 "s_register_operand" "w")]
+  "*
+  return output_move_neon (operands);
+  "
+  [(set_attr "length" "4")
+   (set_attr "type" "neon_store1_1reg")])

No need to specify the "length" here as it's 4 by default.




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