* [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
@ 2018-02-13 3:34 Peter Bergner
2018-02-13 22:34 ` Segher Boessenkool
0 siblings, 1 reply; 6+ messages in thread
From: Peter Bergner @ 2018-02-13 3:34 UTC (permalink / raw)
To: GCC Patches; +Cc: Segher Boessenkool, Bill Schmidt, Jakub Jelinek
PR84279 is a similar problem to PR83399, in that we generate an altivec
load/store through an explicit call to the altivec_{l,st}vx_v4si_2op
pattern and then due to spilling, we end up calling recog() and we match
an earlier pattern, in this case vsx_movv4si_64bit. That is ok, since
this pattern can generate the lvx/stvx insns the altivec patterm can.
However, due to a constraint bug, we end up using the wrong alternative.
The problematic code after spilling looks like:
(insn 92 131 126 2 (parallel [
(set (reg:V4SI 140)
(unspec:V4SI [
(reg:SI 143 [ g ])
(reg:SI 150 [ ar.v ])
(subreg:SI (reg:DI 146) 0)
(subreg:SI (reg:DI 149) 0)
] UNSPEC_VSX_VEC_INIT))
(clobber (scratch:DI))
(clobber (scratch:DI))
]) "bug.i":25 1237 {vsx_init_v4si})
(insn 126 92 95 2 (set (mem/c:V4SI (and:DI (plus:DI (reg/f:DI 111 sfp)
(reg:DI 156))
(const_int -16 [0xfffffffffffffff0])) [3 MEM[(struct A *)&am]+0 S16 A128])
(reg:V4SI 140)) "bug.i":25 1792 {altivec_stvx_v4si_2op})
The vsx_init_v4si pattern forces pseudo 140 to be assigned a GPR, which
should force a reload in insn 126, because the altivec store requires
an altivec register for its src operand. However, after recog(), we
end up using the vsx_movv4si_64bit pattern which looks like:
(define_insn "*vsx_mov<mode>_64bit"
[(set (match_operand:VSX_M 0 "nonimmediate_operand"
"=ZwO, <VSa>, <VSa>, r, we, ?wQ,
?&r, ??r, ??Y, ??r, wo, v,
?<VSa>, *r, v, ??r, wZ, v")
(match_operand:VSX_M 1 "input_operand"
"<VSa>, ZwO, <VSa>, we, r, r,
wQ, Y, r, r, wE, jwM,
?jwM, jwM, W, W, v, wZ"))]
Now we _should_ match using the second to last alternative, but we end up
matching the 8th alternative ("??Y" and "r"). The 8th alternative is used for
storing a GPR, which we have, but the mem we're trying to store to does not
have a valid address for a GPR store. The "bug" is that the "Y" constraint
code, which is implemented by mem_operand_gpr() allows our altivec address
when it should not. The following patch which fixes the ICE adds code to
mem_operand_gpr() which disallows such addresses.
This patch passed bootstrap and retesting on powerpc64le-linux with
no regressions. Ok for mainline?
Peter
gcc/
PR target/84279
* config/rs6000/rs6000.c (mem_operand_gpr): Disallow altivec addresses.
gcc/testsuite/
PR target/84279
* g++.dg/pr84279.C: New test.
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 257606)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -8220,6 +8220,12 @@ mem_operand_gpr (rtx op, machine_mode mo
int extra;
rtx addr = XEXP (op, 0);
+ /* Don't allow altivec type addresses like (mem (and (plus ...))).
+ See PR target/84279. */
+
+ if (GET_CODE (addr) == AND)
+ return false;
+
op = address_offset (addr);
if (op == NULL_RTX)
return true;
Index: gcc/testsuite/g++.dg/pr84279.C
===================================================================
--- gcc/testsuite/g++.dg/pr84279.C (nonexistent)
+++ gcc/testsuite/g++.dg/pr84279.C (working copy)
@@ -0,0 +1,35 @@
+/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */
+/* { dg-skip-if "" { powerpc*-*-darwin* } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=power8" } } */
+/* { dg-options "-O3 -mcpu=power8 -g -fPIC -fvisibility=hidden -fstack-protector-strong" } */
+
+template <typename, typename T> struct E { T e; };
+struct J {
+ unsigned k, l;
+ J (unsigned x, unsigned y) : k(x), l(y) {}
+};
+typedef struct A {
+ J n, p;
+ A ();
+ A (J x, J y) : n(x), p(y) {}
+} *S;
+S t;
+struct B {
+ struct C {
+ S q, r;
+ int u, v;
+ bool m1 (S, A &);
+ J m2 () const;
+ J m3 () const;
+ A m4 () const;
+ };
+ typedef E<unsigned, S> D;
+ void m5 (D *);
+ void m6 (unsigned, A);
+};
+bool B::C::m1 (S, A &x) { bool o; x = m4 (); return o; }
+J B::C::m2 () const { unsigned g (u == 0); unsigned h (v); return J (g, h); }
+J B::C::m3 () const { unsigned g (q != t); unsigned h (r != t); return J (g, h); }
+A B::C::m4 () const { return A (m2 (), m3 ()); }
+void B::m5 (D *c) { unsigned x; C ar; A am; if (ar.m1 (c->e, am)) m6 (x, am); }
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
2018-02-13 3:34 [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4 Peter Bergner
@ 2018-02-13 22:34 ` Segher Boessenkool
2018-02-13 23:07 ` Peter Bergner
0 siblings, 1 reply; 6+ messages in thread
From: Segher Boessenkool @ 2018-02-13 22:34 UTC (permalink / raw)
To: Peter Bergner; +Cc: GCC Patches, Bill Schmidt, Jakub Jelinek
Hi!
On Mon, Feb 12, 2018 at 09:34:30PM -0600, Peter Bergner wrote:
> PR84279 is a similar problem to PR83399, in that we generate an altivec
> load/store through an explicit call to the altivec_{l,st}vx_v4si_2op
> pattern and then due to spilling, we end up calling recog() and we match
> an earlier pattern, in this case vsx_movv4si_64bit. That is ok, since
> this pattern can generate the lvx/stvx insns the altivec patterm can.
> However, due to a constraint bug, we end up using the wrong alternative.
> Now we _should_ match using the second to last alternative, but we end up
> matching the 8th alternative ("??Y" and "r"). The 8th alternative is used for
> storing a GPR, which we have, but the mem we're trying to store to does not
> have a valid address for a GPR store. The "bug" is that the "Y" constraint
> code, which is implemented by mem_operand_gpr() allows our altivec address
> when it should not. The following patch which fixes the ICE adds code to
> mem_operand_gpr() which disallows such addresses.
>
> This patch passed bootstrap and retesting on powerpc64le-linux with
> no regressions. Ok for mainline?
Okay, thanks! Does this need backports?
> --- gcc/testsuite/g++.dg/pr84279.C (nonexistent)
> +++ gcc/testsuite/g++.dg/pr84279.C (working copy)
> @@ -0,0 +1,35 @@
> +/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */
I don't think this needs lp64?
Segher
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
2018-02-13 22:34 ` Segher Boessenkool
@ 2018-02-13 23:07 ` Peter Bergner
2018-02-13 23:51 ` Segher Boessenkool
0 siblings, 1 reply; 6+ messages in thread
From: Peter Bergner @ 2018-02-13 23:07 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: GCC Patches, Bill Schmidt, Jakub Jelinek
On 2/13/18 4:34 PM, Segher Boessenkool wrote:
>> This patch passed bootstrap and retesting on powerpc64le-linux with
>> no regressions. Ok for mainline?
>
> Okay, thanks! Does this need backports?
Committed with your suggested change below. Thanks!
It'd be easy to backport and should be fairly harmless. That said, I was
never able to create a simpler test case, using __builtin_altivec_lvx()
that would end up being re-recog'd as vsx_movv4si_64, so the only way I
know we can hit this is with Kelvin's optimization that replaces aligned
vsx loads/stores with altivec loads/stores and that optimization is only
on trunk.
It's up to you whether you want the backport because you don't trust
me being able to create a failing test case. :-)
>> --- gcc/testsuite/g++.dg/pr84279.C (nonexistent)
>> +++ gcc/testsuite/g++.dg/pr84279.C (working copy)
>> @@ -0,0 +1,35 @@
>> +/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */
>
> I don't think this needs lp64?
Yeah, I think you're right. I'll remove it. Thanks.
Peter
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
2018-02-13 23:07 ` Peter Bergner
@ 2018-02-13 23:51 ` Segher Boessenkool
2018-02-14 1:12 ` Peter Bergner
2018-02-14 15:19 ` Peter Bergner
0 siblings, 2 replies; 6+ messages in thread
From: Segher Boessenkool @ 2018-02-13 23:51 UTC (permalink / raw)
To: Peter Bergner; +Cc: GCC Patches, Bill Schmidt, Jakub Jelinek
On Tue, Feb 13, 2018 at 05:07:26PM -0600, Peter Bergner wrote:
> On 2/13/18 4:34 PM, Segher Boessenkool wrote:
> >> This patch passed bootstrap and retesting on powerpc64le-linux with
> >> no regressions. Ok for mainline?
> >
> > Okay, thanks! Does this need backports?
>
> Committed with your suggested change below. Thanks!
>
> It'd be easy to backport and should be fairly harmless. That said, I was
> never able to create a simpler test case, using __builtin_altivec_lvx()
> that would end up being re-recog'd as vsx_movv4si_64, so the only way I
> know we can hit this is with Kelvin's optimization that replaces aligned
> vsx loads/stores with altivec loads/stores and that optimization is only
> on trunk.
>
> It's up to you whether you want the backport because you don't trust
> me being able to create a failing test case. :-)
We can backport without having a failing testcase. Let's do that for 7
at least?
Segher
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
2018-02-13 23:51 ` Segher Boessenkool
@ 2018-02-14 1:12 ` Peter Bergner
2018-02-14 15:19 ` Peter Bergner
1 sibling, 0 replies; 6+ messages in thread
From: Peter Bergner @ 2018-02-14 1:12 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: GCC Patches, Bill Schmidt, Jakub Jelinek
On 2/13/18 5:51 PM, Segher Boessenkool wrote:
> On Tue, Feb 13, 2018 at 05:07:26PM -0600, Peter Bergner wrote:
>> It's up to you whether you want the backport because you don't trust
>> me being able to create a failing test case. :-)
>
> We can backport without having a failing testcase. Let's do that for 7
> at least?
Ok, I'll test the back port to GCC 7 and commit if no regressions.
Peter
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4
2018-02-13 23:51 ` Segher Boessenkool
2018-02-14 1:12 ` Peter Bergner
@ 2018-02-14 15:19 ` Peter Bergner
1 sibling, 0 replies; 6+ messages in thread
From: Peter Bergner @ 2018-02-14 15:19 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: GCC Patches, Bill Schmidt, Jakub Jelinek
On 2/13/18 5:51 PM, Segher Boessenkool wrote:
> We can backport without having a failing testcase. Let's do that for 7
> at least?
Ok, the backport tested clean, so I committed it. Thanks.
Peter
^ permalink raw reply [flat|nested] 6+ messages in thread
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2018-02-13 3:34 [PATCH, rs6000] Fix PR84279, powerpc64le ICE on cvc4 Peter Bergner
2018-02-13 22:34 ` Segher Boessenkool
2018-02-13 23:07 ` Peter Bergner
2018-02-13 23:51 ` Segher Boessenkool
2018-02-14 1:12 ` Peter Bergner
2018-02-14 15:19 ` Peter Bergner
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