From: Matt Thomas <m...@3am-software.com>
Fix an ICE with the handling of RTL expressions like:
(subreg:QI (mem/c:SI (plus:SI (plus:SI (mult:SI (reg/v:SI 0 %r0 [orig:67 i ]
[67])
(const_int 4 [0x4]))
(reg/v/f:SI 7 %r7 [orig:59 doacross ] [59]))
(const_int 40 [0x28])) [1 MEM[(unsigned int *)doacross_63 + 40B +
i_106 * 4]+0 S4 A32]) 0)
that causes the compilation of libgomp to fail:
during RTL pass: reload
.../libgomp/ordered.c: In function 'GOMP_doacross_wait':
.../libgomp/ordered.c:507:1: internal compiler error: in change_address_1, at
emit-rtl.c:2275
507 | }
| ^
0x10a3462b change_address_1
.../gcc/emit-rtl.c:2275
0x10a353a7 adjust_address_1(rtx_def*, machine_mode, poly_int<1u, long>, int,
int, int, poly_int<1u, long>)
.../gcc/emit-rtl.c:2409
0x10ae2993 alter_subreg(rtx_def**, bool)
.../gcc/final.c:3368
0x10ae25cf cleanup_subreg_operands(rtx_insn*)
.../gcc/final.c:3322
0x110922a3 reload(rtx_insn*, int)
.../gcc/reload1.c:1232
0x10de2bf7 do_reload
.../gcc/ira.c:5812
0x10de3377 execute
.../gcc/ira.c:5986
in a `vax-netbsdelf' build, where an attempt is made to change the mode
of the contained memory reference to the mode of the containing SUBREG.
Such RTL expressions are produced by the VAX shift and rotate patterns
(`ashift', `ashiftrt', `rotate', `rotatert') where the count operand
always has the QI mode regardless of the mode, either SI or DI, of the
datum shifted or rotated.
Such a mode change cannot work where the memory reference uses the
indexed addressing mode, where a multiplier is implied that in the VAX
ISA depends on the width of the memory access requested and therefore
changing the machine mode would change the address calculation as well.
Avoid the attempt then by forcing the reload of any SUBREGs containing
a mode-dependent memory reference, also fixing these regressions:
FAIL: gcc.c-torture/compile/pr46883.c -Os (internal compiler error)
FAIL: gcc.c-torture/compile/pr46883.c -Os (test for excess errors)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 (internal compiler error)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 (test for excess errors)
FAIL: gcc.c-torture/execute/20120808-1.c -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions (internal compiler
error)
FAIL: gcc.c-torture/execute/20120808-1.c -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess
errors)
FAIL: gcc.c-torture/execute/20120808-1.c -O3 -g (internal compiler error)
FAIL: gcc.c-torture/execute/20120808-1.c -O3 -g (test for excess errors)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none (internal compiler error)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none (test for excess errors)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects (internal compiler error)
FAIL: gcc.c-torture/execute/20120808-1.c -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects (test for excess errors)
FAIL: gcc.dg/20050629-1.c (internal compiler error)
FAIL: gcc.dg/20050629-1.c (test for excess errors)
FAIL: c-c++-common/torture/pr53505.c -Os (internal compiler error)
FAIL: c-c++-common/torture/pr53505.c -Os (test for excess errors)
FAIL: gfortran.dg/coarray_failed_images_1.f08 -Os (internal compiler error)
FAIL: gfortran.dg/coarray_stopped_images_1.f08 -Os (internal compiler error)
With test case #0 included it causes a reload with:
(insn 15 14 16 4 (set (reg:SI 31)
(ashift:SI (const_int 1 [0x1])
(subreg:QI (reg:SI 30 [ MEM[(int *)s_8(D) + 4B + _5 * 4] ]) 0)))
"pr58901-0.c":15:12 94 {ashlsi3}
(expr_list:REG_DEAD (reg:SI 30 [ MEM[(int *)s_8(D) + 4B + _5 * 4] ])
(nil)))
as follows:
Reloads for insn # 15
Reload 0: reload_in (SI) = (reg:SI 30 [ MEM[(int *)s_8(D) + 4B + _5 * 4] ])
ALL_REGS, RELOAD_FOR_INPUT (opnum = 2)
reload_in_reg: (reg:SI 30 [ MEM[(int *)s_8(D) + 4B + _5 * 4] ])
reload_reg_rtx: (reg:SI 5 %r5)
resulting in:
(insn 37 14 15 4 (set (reg:SI 5 %r5)
(mem/c:SI (plus:SI (plus:SI (mult:SI (reg/v:SI 1 %r1 [orig:25 i ] [25])
(const_int 4 [0x4]))
(reg/v/f:SI 4 %r4 [orig:29 s ] [29]))
(const_int 4 [0x4])) [1 MEM[(int *)s_8(D) + 4B + _5 * 4]+0 S4
A32])) "pr58901-0.c":15:12 12 {movsi_2}
(nil))
(insn 15 37 16 4 (set (reg:SI 2 %r2 [31])
(ashift:SI (const_int 1 [0x1])
(reg:QI 5 %r5))) "pr58901-0.c":15:12 94 {ashlsi3}
(nil))
and assembly like:
.L3:
movl 4(%r4)[%r1],%r5
ashl %r5,$1,%r2
xorl2 %r2,%r0
incl %r1
cmpl %r1,%r3
jneq .L3
produced for the loop, providing optimization has been enabled.
Likewise with test case #1 the reload of:
(insn 17 16 18 4 (set (reg:SI 34)
(and:SI (subreg:SI (reg/v:DI 27 [ t ]) 4)
(const_int 1 [0x1]))) "pr58901-1.c":18:20 77 {*andsi_const_int}
(expr_list:REG_DEAD (reg/v:DI 27 [ t ])
(nil)))
is as follows:
Reloads for insn # 17
Reload 0: reload_in (DI) = (reg/v:DI 27 [ t ])
reload_out (SI) = (reg:SI 2 %r2 [34])
ALL_REGS, RELOAD_OTHER (opnum = 0)
reload_in_reg: (reg/v:DI 27 [ t ])
reload_out_reg: (reg:SI 2 %r2 [34])
reload_reg_rtx: (reg:DI 4 %r4)
resulting in:
(insn 40 16 17 4 (set (reg:DI 4 %r4)
(mem/c:DI (plus:SI (mult:SI (reg/v:SI 1 %r1 [orig:26 i ] [26])
(const_int 8 [0x8]))
(reg/v/f:SI 3 %r3 [orig:30 s ] [30])) [1 MEM[(const struct s
*)s_13(D) + _7 * 8]+0 S8 A32])) "pr58901-1.c":18:20 11 {movdi}
(nil))
(insn 17 40 41 4 (set (reg:SI 4 %r4)
(and:SI (reg:SI 5 %r5 [+4 ])
(const_int 1 [0x1]))) "pr58901-1.c":18:20 77 {*andsi_const_int}
(nil))
and assembly like:
.L3:
movq (%r3)[%r1],%r4
bicl3 $-2,%r5,%r4
addl2 %r4,%r0
jaoblss %r0,%r1,.L3
First posted at: <https://gcc.gnu.org/ml/gcc/2014-06/msg00060.html>.
2020-11-24 Matt Thomas <m...@3am-software.com>
Maciej W. Rozycki <ma...@linux-mips.org>
gcc/
PR target/58901
* reload.c (push_reload): Also reload the inner expression of a
SUBREG for pseudos associated with a mode-dependent memory
reference.
(find_reloads): Force a reload likewise.
2020-11-24 Maciej W. Rozycki <ma...@linux-mips.org>
gcc/testsuite/
PR target/58901
* gcc.c-torture/compile/pr58901-0.c: New test.
* gcc.c-torture/compile/pr58901-1.c: New test.
---
Hi Eric,
On Fri, 20 Nov 2020, Maciej W. Rozycki wrote:
> > The handling of this family of reloads is supposed to be done by the block
> > of
> > code just above though, i.e. at line 1023. Can't we add the test based on
> > mode_dependent_address_p to this block, e.g. after:
> >
> > || (REG_P (SUBREG_REG (in))
> > && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
> > && !REG_CAN_CHANGE_MODE_P (REGNO (SUBREG_REG (in)),
> > GET_MODE (SUBREG_REG
> > (in)), inmode))))
> >
> > instead?
>
> Thank you for your input, I'll have a look. Coming from Matt this is the
> only change of the series I have just merged without looking into it too
> much, so as not to spend too much time with side issues (there were too
> many already).
You were right about the correct placement of the check, but it was a
part of the solution only.
I looked into why it did not work on its own and (mind that I have not
worked with this part of GCC before) I have realised something was not
right about it. The thing was the reload was only requested as optional
(and later discarded) under the premise of being an optimisation only
(i.e. called from reload.c:4125 in `find_reloads'), while indeed it is
required whether optimising or not, even though the VAX backend does not
appear to produce mode-dependent addresses in the latter case, or at least
I haven't seen it doing so.
So I have investigated what needs to be done for the reload to become
unconditional and come up with this update. Note that we need to handle a
mode change whether it is for the low part of the inner reference or not.
The latter case is what turned out to actually trigger with pr53505.c,
which this update actually produces better code for, removing a useless
move (and frame slot creation for a static register):
@@ -5,7 +5,7 @@
.globl foo
.type foo, @function
foo:
- .word 0x40
+ .word 0
subl2 $4,%sp
movl 4(%ap),%r2
clrl %r0
@@ -18,7 +18,6 @@
calls $0,abort
.L3:
movq (%r2)[%r0],%r4
- movl %r5,%r6
rotl $16,%r5,%r3
bicl2 $-2,%r3
addl2 %r3,%r1
which was of course the result of an unnecessary reload of the outer
expression the original change did.
I have reduced the libgomp build failure and pr53505.c to test cases #0
and #1 included respectively (where #1 actually triggers across all
optimisation levels rather than just `-Os', though with 05/31 this goes
back to `-Os' only); while the failure is VAX-specific code involved is
not, so I think there'll be no harm with including them in the generic
part of our testsuite for good measure.
I think it is interesting to note that with #0 for some reason for the
failure to trigger the struct has to be passed by reference rather than
value and for #1 there has to be the intermediate struct assignment in the
loop; otherwise the indexed addressing mode won't trigger and the base
register will instead be incremented by four.
Also I wonder why with #0 the middle end tries to be too smart and makes
the loop's continuation condition `ne' rather `gt' as with #1, causing the
resulting RTL not to match the pattern for `jaoblss' and consequently more
elaborate code to be produced, even though in both cases the control
statement uses the `<' relational operator. Anyway, that's unrelated.
> It'll take me a couple of days to push the new version through regression
> testing, and I'll post it once that is complete along with any other
> updates someone may request.
I actually missed the high-part case with my first attempt and thankfully
pr53505.c has caught it. It means however that I've had to rerun testing,
and given I have literally only just started it now I expect results Thu
morning only.
NB I find the reindentation resulting in `push_reload' awful, just as I
do either version of the massive logical expression involved. Perhaps we
could factor these out into `static inline' functions sometime, and then
have them split into individual returns within?
Maciej
---
gcc/reload.c | 105 +++++++++++++++---------
gcc/testsuite/gcc.c-torture/compile/pr58901-0.c | 17 +++
gcc/testsuite/gcc.c-torture/compile/pr58901-1.c | 21 ++++
3 files changed, 107 insertions(+), 36 deletions(-)
Index: gcc/gcc/reload.c
===================================================================
--- gcc.orig/gcc/reload.c
+++ gcc/gcc/reload.c
@@ -1043,53 +1043,73 @@ push_reload (rtx in, rtx out, rtx *inloc
Also reload the inner expression if it does not require a secondary
reload but the SUBREG does.
- Finally, reload the inner expression if it is a register that is in
+ Also reload the inner expression if it is a register that is in
the class whose registers cannot be referenced in a different size
and M1 is not the same size as M2. If subreg_lowpart_p is false, we
cannot reload just the inside since we might end up with the wrong
register class. But if it is inside a STRICT_LOW_PART, we have
- no choice, so we hope we do get the right register class there. */
+ no choice, so we hope we do get the right register class there.
+
+ Finally, reload the inner expression if it is a pseudo that will
+ become a MEM and the MEM has a mode-dependent address, as in that
+ case we obviously cannot change the mode of the MEM to that of the
+ containing SUBREG as that would change the interpretation of the
+ address. */
scalar_int_mode inner_mode;
if (in != 0 && GET_CODE (in) == SUBREG
- && (subreg_lowpart_p (in) || strict_low)
&& targetm.can_change_mode_class (GET_MODE (SUBREG_REG (in)),
inmode, rclass)
&& contains_allocatable_reg_of_mode[rclass][GET_MODE (SUBREG_REG (in))]
- && (CONSTANT_P (SUBREG_REG (in))
- || GET_CODE (SUBREG_REG (in)) == PLUS
- || strict_low
- || (((REG_P (SUBREG_REG (in))
- && REGNO (SUBREG_REG (in)) >= FIRST_PSEUDO_REGISTER)
- || MEM_P (SUBREG_REG (in)))
- && (paradoxical_subreg_p (inmode, GET_MODE (SUBREG_REG (in)))
- || (known_le (GET_MODE_SIZE (inmode), UNITS_PER_WORD)
- && is_a <scalar_int_mode> (GET_MODE (SUBREG_REG (in)),
- &inner_mode)
- && GET_MODE_SIZE (inner_mode) <= UNITS_PER_WORD
- && paradoxical_subreg_p (inmode, inner_mode)
- && LOAD_EXTEND_OP (inner_mode) != UNKNOWN)
- || (WORD_REGISTER_OPERATIONS
- && partial_subreg_p (inmode, GET_MODE (SUBREG_REG (in)))
- && (known_equal_after_align_down
- (GET_MODE_SIZE (inmode) - 1,
- GET_MODE_SIZE (GET_MODE (SUBREG_REG (in))) - 1,
- UNITS_PER_WORD)))))
- || (REG_P (SUBREG_REG (in))
- && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
- /* The case where out is nonzero
- is handled differently in the following statement. */
- && (out == 0 || subreg_lowpart_p (in))
- && (complex_word_subreg_p (inmode, SUBREG_REG (in))
- || !targetm.hard_regno_mode_ok (subreg_regno (in), inmode)))
- || (secondary_reload_class (1, rclass, inmode, in) != NO_REGS
- && (secondary_reload_class (1, rclass, GET_MODE (SUBREG_REG (in)),
- SUBREG_REG (in))
- == NO_REGS))
+ && (strict_low
+ || (subreg_lowpart_p (in)
+ && (CONSTANT_P (SUBREG_REG (in))
+ || GET_CODE (SUBREG_REG (in)) == PLUS
+ || strict_low
+ || (((REG_P (SUBREG_REG (in))
+ && REGNO (SUBREG_REG (in)) >= FIRST_PSEUDO_REGISTER)
+ || MEM_P (SUBREG_REG (in)))
+ && (paradoxical_subreg_p (inmode,
+ GET_MODE (SUBREG_REG (in)))
+ || (known_le (GET_MODE_SIZE (inmode), UNITS_PER_WORD)
+ && is_a <scalar_int_mode> (GET_MODE (SUBREG_REG
+ (in)),
+ &inner_mode)
+ && GET_MODE_SIZE (inner_mode) <= UNITS_PER_WORD
+ && paradoxical_subreg_p (inmode, inner_mode)
+ && LOAD_EXTEND_OP (inner_mode) != UNKNOWN)
+ || (WORD_REGISTER_OPERATIONS
+ && partial_subreg_p (inmode,
+ GET_MODE (SUBREG_REG (in)))
+ && (known_equal_after_align_down
+ (GET_MODE_SIZE (inmode) - 1,
+ GET_MODE_SIZE (GET_MODE (SUBREG_REG
+ (in))) - 1,
+ UNITS_PER_WORD)))))
+ || (REG_P (SUBREG_REG (in))
+ && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
+ /* The case where out is nonzero
+ is handled differently in the following statement. */
+ && (out == 0 || subreg_lowpart_p (in))
+ && (complex_word_subreg_p (inmode, SUBREG_REG (in))
+ || !targetm.hard_regno_mode_ok (subreg_regno (in),
+ inmode)))
+ || (secondary_reload_class (1, rclass, inmode, in) != NO_REGS
+ && (secondary_reload_class (1, rclass,
+ GET_MODE (SUBREG_REG (in)),
+ SUBREG_REG (in))
+ == NO_REGS))
+ || (REG_P (SUBREG_REG (in))
+ && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
+ && !REG_CAN_CHANGE_MODE_P (REGNO (SUBREG_REG (in)),
+ GET_MODE (SUBREG_REG (in)),
+ inmode))))
|| (REG_P (SUBREG_REG (in))
- && REGNO (SUBREG_REG (in)) < FIRST_PSEUDO_REGISTER
- && !REG_CAN_CHANGE_MODE_P (REGNO (SUBREG_REG (in)),
- GET_MODE (SUBREG_REG (in)), inmode))))
+ && REGNO (SUBREG_REG (in)) >= FIRST_PSEUDO_REGISTER
+ && reg_equiv_mem (REGNO (SUBREG_REG (in)))
+ && (mode_dependent_address_p
+ (XEXP (reg_equiv_mem (REGNO (SUBREG_REG (in))), 0),
+ MEM_ADDR_SPACE (reg_equiv_mem (REGNO (SUBREG_REG (in)))))))))
{
#ifdef LIMIT_RELOAD_CLASS
in_subreg_loc = inloc;
@@ -3157,6 +3177,19 @@ find_reloads (rtx_insn *insn, int replac
&& paradoxical_subreg_p (operand_mode[i],
inner_mode)
&& LOAD_EXTEND_OP (inner_mode) != UNKNOWN)))
+ /* We must force a reload of a SUBREG's inner expression
+ if it is a pseudo that will become a MEM and the MEM
+ has a mode-dependent address, as in that case we
+ obviously cannot change the mode of the MEM to that
+ of the containing SUBREG as that would change the
+ interpretation of the address. */
+ || (REG_P (operand)
+ && REGNO (operand) >= FIRST_PSEUDO_REGISTER
+ && reg_equiv_mem (REGNO (operand))
+ && (mode_dependent_address_p
+ (XEXP (reg_equiv_mem (REGNO (operand)), 0),
+ (MEM_ADDR_SPACE
+ (reg_equiv_mem (REGNO (operand)))))))
)
force_reload = 1;
}
Index: gcc/gcc/testsuite/gcc.c-torture/compile/pr58901-0.c
===================================================================
--- /dev/null
+++ gcc/gcc/testsuite/gcc.c-torture/compile/pr58901-0.c
@@ -0,0 +1,17 @@
+typedef signed int __attribute__ ((mode (SI))) int_t;
+
+struct s
+{
+ int_t n;
+ int_t c[];
+};
+
+int_t
+ashlsi (int_t x, const struct s *s)
+{
+ int_t i;
+
+ for (i = 0; i < s->n; i++)
+ x ^= 1 << s->c[i];
+ return x;
+}
Index: gcc/gcc/testsuite/gcc.c-torture/compile/pr58901-1.c
===================================================================
--- /dev/null
+++ gcc/gcc/testsuite/gcc.c-torture/compile/pr58901-1.c
@@ -0,0 +1,21 @@
+typedef int __attribute__ ((mode (SI))) int_t;
+
+struct s
+{
+ int_t n;
+ int_t m : 1;
+ int_t l : 31;
+};
+
+int_t
+movdi (int_t x, const struct s *s)
+{
+ int_t i;
+
+ for (i = 0; i < x; i++)
+ {
+ const struct s t = s[i];
+ x += t.m ? 1 : 0;
+ }
+ return x;
+}
