[See:
https://gcc.gnu.org/pipermail/gcc-patches/2020-March/541694.html
https://gcc.gnu.org/pipermail/gcc-patches/2020-March/541759.html
for a walkthrough of what goes wrong in the testcase, but hopefully
the change makes sense on first principles.]
simplify_operand_subreg tries to detect whether the allocation for
a pseudo in a paradoxical subreg is also valid for the outer mode.
The condition it used to check for an invalid combination was:
else if (REG_P (reg)
&& REGNO (reg) >= FIRST_PSEUDO_REGISTER
&& (hard_regno = lra_get_regno_hard_regno (REGNO (reg))) >= 0
&& (hard_regno_nregs (hard_regno, innermode)
< hard_regno_nregs (hard_regno, mode))
&& (regclass = lra_get_allocno_class (REGNO (reg)))
&& (type != OP_IN
|| !in_hard_reg_set_p (reg_class_contents[regclass],
mode, hard_regno)
|| overlaps_hard_reg_set_p (lra_no_alloc_regs,
mode, hard_regno)))
I think there are two problems with this:
(1) It never actually checks whether the hard register is valid for the
outer mode (in the hard_regno_mode_ok sense). If it isn't, any attempt
to reload in the outer mode is likely to cycle, because the implied
regno/mode combination will be just as invalid next time
curr_insn_transform sees the subreg.
(2) The check is valid for little-endian only. For big-endian we need
to move hard_regno backwards.
Using simplify_subreg_regno should avoid both problems.
As the existing comment says, IRA should always take subreg references
into account when allocating hard registers, so this fix-up should only
really be needed for pseudos allocated by LRA itself.
Tested on aarch64-linux-gnu, armeb-eabi and x86_64-linux-gnu. OK for master?
I think for backports it would be safer to go with Tamar's patch.
Thanks,
Richard
gcc/
2020-03-10 Richard Sandiford <richard.sandif...@arm.com>
PR rtl-optimization/94052
* lra-constraints.c (simplify_operand_subreg): Reload the inner
register of a paradoxical subreg if simplify_subreg_regno fails
to give a valid hard register for the outer mode.
gcc/testsuite/
2020-03-05 Tamar Christina <tamar.christ...@arm.com>
PR target/94052
* gcc.target/aarch64/pr94052.C: New test.
---
gcc/lra-constraints.c | 24 +--
gcc/testsuite/g++.target/aarch64/pr94052.C | 174 +++++++++++++++++++++
2 files changed, 188 insertions(+), 10 deletions(-)
create mode 100644 gcc/testsuite/g++.target/aarch64/pr94052.C
diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index f71e0c9ff8d..bf6d4a2fd4b 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -1489,7 +1489,7 @@ static bool process_address (int, bool, rtx_insn **,
rtx_insn **);
static bool
simplify_operand_subreg (int nop, machine_mode reg_mode)
{
- int hard_regno;
+ int hard_regno, inner_hard_regno;
rtx_insn *before, *after;
machine_mode mode, innermode;
rtx reg, new_reg;
@@ -1735,15 +1735,19 @@ simplify_operand_subreg (int nop, machine_mode reg_mode)
for the new uses. */
else if (REG_P (reg)
&& REGNO (reg) >= FIRST_PSEUDO_REGISTER
- && (hard_regno = lra_get_regno_hard_regno (REGNO (reg))) >= 0
- && (hard_regno_nregs (hard_regno, innermode)
- < hard_regno_nregs (hard_regno, mode))
- && (regclass = lra_get_allocno_class (REGNO (reg)))
- && (type != OP_IN
- || !in_hard_reg_set_p (reg_class_contents[regclass],
- mode, hard_regno)
- || overlaps_hard_reg_set_p (lra_no_alloc_regs,
- mode, hard_regno)))
+ && paradoxical_subreg_p (operand)
+ && (inner_hard_regno = lra_get_regno_hard_regno (REGNO (reg))) >= 0
+ && ((hard_regno
+ = simplify_subreg_regno (inner_hard_regno, innermode,
+ SUBREG_BYTE (operand), mode)) < 0
+ || ((hard_regno_nregs (inner_hard_regno, innermode)
+ < hard_regno_nregs (hard_regno, mode))
+ && (regclass = lra_get_allocno_class (REGNO (reg)))
+ && (type != OP_IN
+ || !in_hard_reg_set_p (reg_class_contents[regclass],
+ mode, hard_regno)
+ || overlaps_hard_reg_set_p (lra_no_alloc_regs,
+ mode, hard_regno)))))
{
/* The class will be defined later in curr_insn_transform. */
enum reg_class rclass
diff --git a/gcc/testsuite/g++.target/aarch64/pr94052.C
b/gcc/testsuite/g++.target/aarch64/pr94052.C
new file mode 100644
index 00000000000..d36c9bdc158
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/pr94052.C
@@ -0,0 +1,174 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O2 -std=gnu++11 -w" } */
+
+namespace c {
+typedef int d;
+template <typename e> struct f { typedef e g; };
+template <bool, typename> struct h;
+template <typename e> e aa(typename f<e>::g i) { return i; }
+template <typename, typename> struct j {};
+template <d, typename> struct k;
+template <class l, class m> struct k<1, j<l, m>> { typedef m g; };
+template <d n, class l, class m> typename k<n, j<l, m>>::g ab(j<l, m>);
+} // namespace c
+typedef long d;
+typedef char o;
+typedef int p;
+typedef char q;
+typedef int r;
+namespace {
+struct s;
+constexpr d t = 6;
+template <typename> class ad {
+public:
+ static constexpr d u = t;
+ d v();
+ d x();
+ d y();
+};
+class z : ad<int> {};
+struct ae {
+ p af;
+};
+class ag {
+public:
+ ae ah();
+};
+} // namespace
+typedef __Int32x4_t ai;
+typedef struct {
+ ai aj[2];
+} ak;
+typedef int al;
+void am(p *a, ai b) { __builtin_aarch64_st1v4si(a, b); }
+namespace an {
+class ao {
+public:
+ bool operator==(ao);
+ d v();
+ d x();
+};
+class ap : public ad<r> {};
+class aq {
+public:
+ c::j<int, int> ar();
+ int as();
+ int at();
+};
+class au {
+public:
+ virtual d av(d);
+ virtual ap aw();
+ virtual ag ax();
+};
+class ay {};
+class az {
+ virtual void ba(const ay &, const s &);
+};
+using bb = az;
+class bc;
+class bd : bb {
+ void ba(const ay &, const s &);
+ bc *be;
+ bc *bf;
+ bc *bg;
+ aq bh;
+ int bi;
+ int bj;
+ ao bk;
+};
+namespace bl {
+namespace bm {
+namespace bn {
+class bo;
+}
+} // namespace bm
+} // namespace bl
+namespace bn {
+template <typename ac = c::h<0, bl::bm ::bn::bo>>
+ai bp(ac *, ac *, ac *, al, al, al, d, p);
+template <typename ac = c::h<0, bl::bm ::bn::bo>>
+ak bq(ac *br, ac *bs, ac *bt, al bu, al bv, al bw, d bx, int, int by) {
+ ak{bp(br, bs, bt, bu, bv, bw, bx, by), bp(br, bs, bt, bu, bv, bw, bx, by)};
+}
+template <typename ac = c::h<0, bl::bm ::bn::bo>>
+ak bz(ac *, ac *, ac *, al, al, al &, int, p);
+template <int> void ca(p *, const ak &);
+template <> void ca<1>(p *buffer, const ak &cb) {
+ am(buffer, cb.aj[0]);
+ am(buffer + 4, cb.aj[1]);
+}
+int cc(int, int);
+} // namespace bn
+class bc {
+public:
+ virtual au *cd();
+};
+class ce {
+public:
+ q *cf();
+};
+template <d> struct cg {
+ template <typename ch> static void ci(ay, z cj, ch ck) { ck(cj); }
+};
+template <typename ch> void cl(ay w, ch ck) {
+ z cj;
+ cg<z::u>::ci(w, cj, c::aa<ch>(ck));
+}
+namespace {
+template <typename T1, typename cm, int cn> class co {
+public:
+ static void convolve(ay, int cs, bc *cp, bc *cq, bc *cr, aq cw, int, ao ct) {
+ int by = cp->cd()->ax().ah().af;
+ int cu = cq->cd()->ax().ah().af;
+ cp->cd()->aw().v();
+ int cv = cp->cd()->aw().x();
+ cp->cd()->aw().y();
+ cp->cd()->aw();
+ int da = cr->cd()->aw().x();
+ int cx = cq->cd()->aw().x();
+ cq->cd()->aw().y();
+ int cy = cr->cd()->av(0);
+ int cz = cr->cd()->av(1);
+ bn::cc(cs, cn);
+ int de = c::ab<1>(cw.ar());
+ cw.as();
+ cw.at();
+ ay db;
+ ce dc;
+ ce dd;
+ ce w;
+ q *di = w.cf();
+ cl(db, [&](z) {
+ int df;
+ dc;
+ di;
+ cx;
+ auto dg(cu);
+ auto dh(cu);
+ auto dl(cu);
+ for (; cz; df += de) {
+ auto br = reinterpret_cast<T1 *>(cv);
+ auto bs = reinterpret_cast<T1 *>(cv);
+ auto bt = reinterpret_cast<T1 *>(df * ct.x());
+ auto dj = reinterpret_cast<cm *>(dd.cf() + da);
+ for (int dk; dk < cy; dk += cs, dj += cs)
+ if (ct == ao()) {
+ auto vres = bn::bz(br, bs, bt, dg, dh, dl, cn, by);
+ bn::ca<cn>(dj, vres);
+ } else
+ bn::bq(br, bs, bt, dg, dh, dl, ct.v(), cn, by);
+ }
+ });
+ }
+};
+template <typename T1, typename cm>
+void bz(ay dm, int cs, bc *cp, bc *cq, bc *cr, aq cw, int dn, ao ct) {
+ co<T1, cm, 1>::convolve(dm, cs, cp, cq, cr, cw, dn, ct);
+ co<T1, cm, 2>::convolve(dm, cs, cp, cq, cr, cw, dn, ct);
+}
+} // namespace
+void bd::ba(const ay &dm, const s &) {
+ bz<o, p>(dm, bi, be, bg, bf, bh, bj, bk);
+}
+} // namespace an
--
2.17.1
