On Fri, 30 Oct 2020 at 20:11, Vladimir Makarov via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The following patch implements taking insn scratch requirements into
> account in global RA (IRA). Before the patch IRA simply ignored insn
> scratches. Only LRA took the scratches into account and assigned hard
> registers to scratches if neccessary. In some cases it resulted in
> spilling pseudos who got hard registers in IRA and as a consequence in
> violating a good IRA assignment.
>
> The patch changes insn scratches which require registers for all
> insn alternatives (in other words w/o X constraint in scratch
> constraint string). This is done before IRA staring its work. LRA
> still continue to change the rest scratches (with X constraint and in
> insn created during IRA) into pseudos. As before the patch at the end
> of LRA work, spilled scratch pseudos (for which X constraint was
> chosen) changed into scratches back.
>
> The patch was successfully bootstrapped and tested on x86-64, ppc64,
> aarch64, s390x. There are few new GCC test failures on ppc64 and
> s390x which can be fixed by adding hints to scratch constraints in ppc
> md file and by changing expected test output (as hard register
> assignment was changed a bit). I'll submit the patches for approval a
> bit later.
>
>
> 2020-10-30 Vladimir Makarov <vmaka...@redhat.com>
>
> * lra.c (get_scratch_reg): New function.
> (remove_scratches_1): Rename remove_insn_scratches. Use
> ira_remove_insn_scratches and get_scratch_reg.
> (remove_scratches): Do not
> initialize scratches, scratch_bitmap, and scratch_operand_bitmap.
> (lra): Call ira_restore_scratches instead of restore_scratches.
> (struct sloc, sloc_t, scratches, scratch_bitmap)
> (scratch_operand_bitmap, lra_former_scratch_p)
> (lra_former_scratch_operand_p, lra_register_new_scratch_op,
> restore_scratches): Move them to ...
> * ira.c: ... here.
> (former_scratch_p, former_scratch_operand_p): Rename to
> ira_former_scratch_p and ira_former_scratch_operand_p.
> (contains_X_constraint_p): New function.
> (register_new_scratch_op): Rename to ira_register_new_scratch_op.
> Change it to work for IRA and LRA.
> (restore_scratches): Rename to ira_restore_scratches.
> (get_scratch_reg, ira_remove_insn_scratches): New functions.
> (ira): Call ira_remove_scratches if we use LRA.
> * ira.h (ira_former_scratch_p, ira_former_scratch_operand_p): New
> prototypes.
> (ira_register_new_scratch_op, ira_restore_scratches): New
> prototypes.
> (ira_remove_insn_scratches): New prototype.
> * lra-int.h (lra_former_scratch_p, lra_former_scratch_operand_p):
> Remove prototypes.
> (lra_register_new_scratch_op): Ditto.
> * lra-constraints.c: Rename lra_former_scratch_p and
> lra_former_scratch_p to ira_former_scratch_p and to
> ira_former_scratch_p.
> * lra-remat.c: Ditto.
> * lra-spills.c: Rename lra_former_scratch_p to
> ira_former_scratch_p.
>
Hi,
This patch causes ICEs on arm (eg arm-none-linux-gnueabi)
gcc.c-torture/compile/sync-3.c -O1 (internal compiler error)
gcc.c-torture/compile/sync-3.c -O2 (internal compiler error)
gcc.c-torture/compile/sync-3.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none (internal compiler error)
gcc.c-torture/compile/sync-3.c -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects (internal compiler error)
gcc.c-torture/compile/sync-3.c -O3 -g (internal compiler error)
gcc.c-torture/compile/sync-3.c -Os (internal compiler error)
gcc.log says:
FAIL: gcc.c-torture/compile/sync-3.c -O1 (internal compiler error)
PASS: gcc.c-torture/compile/sync-3.c -O1 (test for warnings, line )
FAIL: gcc.c-torture/compile/sync-3.c -O1 (test for excess errors)
Excess errors:
during RTL pass: ira
/gcc/testsuite/gcc.c-torture/compile/sync-3.c:85:1: internal compiler
error: Segmentation fault
0xcf8b1f crash_signal
/gcc/toplev.c:330
0xaeb0a0 fix_reg_equiv_init
/gcc/ira.c:2671
0xaf2113 find_moveable_pseudos
/gcc/ira.c:4874
0xaf48e8 ira
/gcc/ira.c:5533
0xaf48e8 execute
/gcc/ira.c:5861
FAIL: gcc.c-torture/compile/sync-3.c -O2 (internal compiler error)
PASS: gcc.c-torture/compile/sync-3.c -O2 (test for warnings, line )
FAIL: gcc.c-torture/compile/sync-3.c -O2 (test for excess errors)
Excess errors:
during RTL pass: ira
/gcc/testsuite/gcc.c-torture/compile/sync-3.c:85:1: internal compiler
error: Segmentation fault
0xcf8b1f crash_signal
/gcc/toplev.c:330
0xaeb0a9 safe_as_a<rtx_insn_list*, rtx_def>
/gcc/is-a.h:210
0xaeb0a9 rtx_insn_list::next() const
/gcc/rtl.h:1408
0xaeb0a9 fix_reg_equiv_init
/gcc/ira.c:2683
0xaf2113 find_moveable_pseudos
/gcc/ira.c:4874
0xaf48e8 ira
/gcc/ira.c:5533
0xaf48e8 execute
/gcc/ira.c:5861
Christophe
