On Mon, Oct 16, 2023 at 01:11:01PM -0600, Jeff Law wrote:
> > gcc/ChangeLog:
> >
> > * Makefile.in: Add fold-mem-offsets.o.
> > * passes.def: Schedule a new pass.
> > * tree-pass.h (make_pass_fold_mem_offsets): Declare.
> > * common.opt: New options.
> > * doc/invoke.texi: Document new option.
> > * fold-mem-offsets.cc: New file.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.target/riscv/fold-mem-offsets-1.c: New test.
> > * gcc.target/riscv/fold-mem-offsets-2.c: New test.
> > * gcc.target/riscv/fold-mem-offsets-3.c: New test.
> Thanks, I've pushed this to the trunk.
This breaks profiledbootstrap on powerpc64le-linux.
>From what I can see, the pass works one basic block at a time and
will punt on any non-DEBUG_INSN uses outside of the current block
(I believe because of the
/* This use affects instructions outside of CAN_FOLD_INSNS. */
if (!bitmap_bit_p (&can_fold_insns, INSN_UID (use)))
return 0;
test and can_fold_insns only set in do_analysis (when processing insns in
current bb, cleared at the end) or results of get_single_def_in_bb
(which are checked to be in the same bb).
But, while get_single_def_in_bb checks for
if (DF_INSN_LUID (def) > DF_INSN_LUID (insn))
return NULL;
(OT, why not DF_INSN_INFO_LUID (DF_REF_INSN_INFO (ref_chain->ref))
instead of DF_INSN_LUID (def), then it doesn't need to look up
DF_INSN_INFO_GET (def)?), nothing when walking all uses of def does such
luid check.
The basic block in the PR in question has:
...
(insn 212 210 215 25 (set (mem/f:DI (reg/v/f:DI 10 10 [orig:152 last_viable ]
[152]) [2 *last_viable_336+0 S8 A64])
(reg/f:DI 9 9 [orig:155 _342 ] [155])) "pr111601.ii":50:17 683
{*movdi_internal64}
(expr_list:REG_DEAD (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
(nil)))
(insn 215 212 484 25 (set (reg:DI 5 5 [226])
(const_int 0 [0])) "pr111601.ii":52:12 683 {*movdi_internal64}
(expr_list:REG_EQUIV (const_int 0 [0])
(nil)))
(insn 484 215 218 25 (set (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
(reg/f:DI 9 9 [orig:155 _342 ] [155])) "pr111601.ii":52:12 683
{*movdi_internal64}
(nil))
...
(insn 564 214 216 25 (set (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
(plus:DI (reg/v/f:DI 10 10 [orig:152 last_viable ] [152])
(const_int 96 [0x60]))) "pr111601.ii":52:12 66 {*adddi3}
(nil))
(insn 216 564 219 25 (set (mem/f:DI (reg/v/f:DI 10 10 [orig:152 last_viable ]
[152]) [2 _343->next+0 S8 A64])
(reg:DI 5 5 [226])) "pr111601.ii":52:12 683 {*movdi_internal64}
(expr_list:REG_DEAD (reg:DI 5 5 [226])
(nil)))
...
and when asking for all uses of %r10 from def 564, it will see uses
in 216 and 212; the former is after the += 96 addition and gets changed
to load from %r10+96 with the addition being dropped, but there is
the other store which is a use across the backedge and when reached
from other edges certainly doesn't have the + 96 addition anywhere,
so the pass doesn't actually change that location.
Haven't bootstrapped/regtested this yet, will start momentarily,
posting here just in case I'm missing something important.
2023-11-27 Jakub Jelinek <ja...@redhat.com>
PR bootstrap/111601
* fold-mem-offsets.cc (fold_offsets): Punt if use appears before
def in the basic block.
* g++.dg/opt/pr111601.C: New test.
--- gcc/fold-mem-offsets.cc.jj 2023-11-02 07:49:17.060865772 +0100
+++ gcc/fold-mem-offsets.cc 2023-11-27 21:35:35.089007365 +0100
@@ -511,6 +511,7 @@ fold_offsets (rtx_insn *insn, rtx reg, b
if (!success)
return 0;
+ unsigned luid = DF_INSN_LUID (def);
for (ref_link = uses; ref_link; ref_link = ref_link->next)
{
rtx_insn *use = DF_REF_INSN (ref_link->ref);
@@ -534,6 +535,11 @@ fold_offsets (rtx_insn *insn, rtx reg, b
if (use_set && MEM_P (SET_DEST (use_set))
&& reg_mentioned_p (dest, SET_SRC (use_set)))
return 0;
+
+ /* Punt if use appears before def in the basic block. See
+ PR111601. */
+ if (DF_INSN_INFO_LUID (DF_REF_INSN_INFO (ref_link->ref)) < luid)
+ return 0;
}
bitmap_set_bit (&can_fold_insns, INSN_UID (def));
--- gcc/testsuite/g++.dg/opt/pr111601.C.jj 2023-11-27 21:33:12.605006881
+0100
+++ gcc/testsuite/g++.dg/opt/pr111601.C 2023-11-27 21:34:47.267678510 +0100
@@ -0,0 +1,86 @@
+// PR bootstrap/111601
+// { dg-do run { target c++11 } }
+// { dg-options "-O2 -fno-exceptions -fno-rtti -fprofile-generate" }
+// { dg-require-profiling "-fprofile-generate" }
+// { dg-final { cleanup-coverage-files } }
+
+struct tree_base
+{
+ int code:16;
+};
+struct saved_scope
+{
+ void *pad[14];
+ int x_processing_template_decl;
+};
+struct saved_scope *scope_chain;
+struct z_candidate
+{
+ tree_base *fn;
+ void *pad[11];
+ z_candidate *next;
+ int viable;
+ int flags;
+};
+
+__attribute__((noipa)) struct z_candidate *
+splice_viable (struct z_candidate *cands, bool strict_p, bool *any_viable_p)
+{
+ struct z_candidate *viable;
+ struct z_candidate **last_viable;
+ struct z_candidate **cand;
+ bool found_strictly_viable = false;
+ if (scope_chain->x_processing_template_decl)
+ strict_p = true;
+ viable = (z_candidate *) 0;
+ last_viable = &viable;
+ *any_viable_p = false;
+ cand = &cands;
+ while (*cand)
+ {
+ struct z_candidate *c = *cand;
+ if (!strict_p && (c->viable == 1 || ((int) (c->fn)->code) == 273))
+ {
+ strict_p = true;
+ if (viable && !found_strictly_viable)
+ {
+ *any_viable_p = false;
+ *last_viable = cands;
+ cands = viable;
+ viable = (z_candidate *) 0;
+ last_viable = &viable;
+ }
+ }
+ if (strict_p ? c->viable == 1 : c->viable)
+ {
+ *last_viable = c;
+ *cand = c->next;
+ c->next = (z_candidate *) 0;
+ last_viable = &c->next;
+ *any_viable_p = true;
+ if (c->viable == 1)
+ found_strictly_viable = true;
+ }
+ else
+ cand = &c->next;
+ }
+ return viable ? viable : cands;
+}
+
+int
+main ()
+{
+ saved_scope s{};
+ scope_chain = &s;
+ z_candidate z[4] = {};
+ z[0].next = &z[1];
+ z[1].viable = 1;
+ z[1].next = &z[2];
+ z[2].viable = 1;
+ z[2].next = &z[3];
+ bool b;
+ z_candidate *c = splice_viable (&z[0], true, &b);
+ if (c != &z[1] || z[1].next != &z[2] || z[2].next)
+ __builtin_abort ();
+ return 0;
+}
Jakub
