On Mon, May 30, 2022 at 09:35:43AM +0100, Richard Sandiford wrote:
> "H.J. Lu" <hjl.to...@gmail.com> writes:
> > ---
> > RTL DSE tracks redundant constant stores within a basic block. When RTL
> > loop invariant motion hoists a constant initialization out of the loop
> > into a separate basic block, the constant store value becomes unknown
> > within the original basic block. When recording store for RTL DSE, check
> > if the source register is set only once to a constant by a non-partial
> > unconditional load. If yes, record the constant as the constant store
> > source. It eliminates unrolled zero stores after memset 0 in a loop
> > where a vector register is used as the zero store source.
> >
> > Extract find_single_def_src from loop-iv.cc and move it to df-core.cc:
> >
> > 1. Rename to df_find_single_def_src.
> > 2. Change the argument to rtx and use rtx_equal_p.
> > 3. Return null for partial or conditional defs.
> >
> > gcc/
> >
> > PR rtl-optimization/105638
> > * df-core.cc (df_find_single_def_sr): Moved and renamed from
> > find_single_def_src in loop-iv.cc. Change the argument to rtx
> > and use rtx_equal_p. Return null for partial or conditional
> > defs.
> > * df.h (df_find_single_def_src): New prototype.
> > * dse.cc (record_store): Use the constant source if the source
> > register is set only once.
> > * loop-iv.cc (find_single_def_src): Moved to df-core.cc.
> > (replace_single_def_regs): Replace find_single_def_src with
> > df_find_single_def_src.
> >
> > gcc/testsuite/
> >
> > PR rtl-optimization/105638
> > * g++.target/i386/pr105638.C: New test.
> > ---
> > gcc/df-core.cc | 44 +++++++++++++++++++++++
> > gcc/df.h | 1 +
> > gcc/dse.cc | 14 ++++++++
> > gcc/loop-iv.cc | 45 +-----------------------
> > gcc/testsuite/g++.target/i386/pr105638.C | 44 +++++++++++++++++++++++
> > 5 files changed, 104 insertions(+), 44 deletions(-)
> > create mode 100644 gcc/testsuite/g++.target/i386/pr105638.C
> >
> > diff --git a/gcc/df-core.cc b/gcc/df-core.cc
> > index a901b84878f..f9b4de8eb7a 100644
> > --- a/gcc/df-core.cc
> > +++ b/gcc/df-core.cc
> > @@ -2009,6 +2009,50 @@ df_reg_used (rtx_insn *insn, rtx reg)
> > return df_find_use (insn, reg) != NULL;
> > }
> >
> > +/* If REG has a single definition, return its known value, otherwise return
> > + null. */
> > +
> > +rtx
> > +df_find_single_def_src (rtx reg)
> > +{
> > + rtx src = NULL_RTX;
> > +
> > + /* Don't look through unbounded number of single definition REG copies,
> > + there might be loops for sources with uninitialized variables. */
> > + for (int cnt = 0; cnt < 128; cnt++)
> > + {
> > + df_ref adef = DF_REG_DEF_CHAIN (REGNO (reg));
> > + if (adef == NULL || DF_REF_NEXT_REG (adef) != NULL
> > + || DF_REF_IS_ARTIFICIAL (adef)
> > + || (DF_REF_FLAGS (adef)
> > + & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
> > + return NULL_RTX;
> > +
> > + rtx set = single_set (DF_REF_INSN (adef));
> > + if (set == NULL || !rtx_equal_p (SET_DEST (set), reg))
> > + return NULL_RTX;
> > +
> > + rtx note = find_reg_equal_equiv_note (DF_REF_INSN (adef));
> > + if (note && function_invariant_p (XEXP (note, 0)))
> > + {
> > + src = XEXP (note, 0);
> > + break;
> > + }
>
> Seems simpler to return this directly, rather than break and then
> check function_invariant_p again.
Fixed.
>
> > + src = SET_SRC (set);
> > +
> > + if (REG_P (src))
> > + {
> > + reg = src;
> > + continue;
> > + }
> > + break;
> > + }
> > + if (!function_invariant_p (src))
> > + return NULL_RTX;
> > +
> > + return src;
> > +}
> > +
> >
> >
> > /*----------------------------------------------------------------------------
> > Debugging and printing functions.
> > diff --git a/gcc/df.h b/gcc/df.h
> > index bd329205d08..71e249ad20a 100644
> > --- a/gcc/df.h
> > +++ b/gcc/df.h
> > @@ -991,6 +991,7 @@ extern df_ref df_find_def (rtx_insn *, rtx);
> > extern bool df_reg_defined (rtx_insn *, rtx);
> > extern df_ref df_find_use (rtx_insn *, rtx);
> > extern bool df_reg_used (rtx_insn *, rtx);
> > +extern rtx df_find_single_def_src (rtx);
> > extern void df_worklist_dataflow (struct dataflow *,bitmap, int *, int);
> > extern void df_print_regset (FILE *file, const_bitmap r);
> > extern void df_print_word_regset (FILE *file, const_bitmap r);
> > diff --git a/gcc/dse.cc b/gcc/dse.cc
> > index 30c11cee034..c915266f025 100644
> > --- a/gcc/dse.cc
> > +++ b/gcc/dse.cc
> > @@ -1508,6 +1508,20 @@ record_store (rtx body, bb_info_t bb_info)
> >
> > if (tem && CONSTANT_P (tem))
> > const_rhs = tem;
> > + else
> > + {
> > + /* If RHS is set only once to a constant, set CONST_RHS
> > + to the constant. */
> > + rtx def_src = df_find_single_def_src (rhs);
> > + if (def_src != nullptr && CONSTANT_P (def_src))
> > + {
> > + df_ref def = DF_REG_DEF_CHAIN (REGNO (rhs));
> > + rtx_insn *def_insn = DF_REF_INSN (def);
> > + rtx def_body = single_set (def_insn);
> > + if (rhs == SET_DEST (def_body))
> > + const_rhs = def_src;
> > + }
> > + }
>
> This shouldn't be necessary now: we can rely on def_src being correct.
>
> I.e. I think this can just be:
>
> rtx def_src = df_find_single_def_src (rhs);
> if (def_src != nullptr && CONSTANT_P (def_src))
> const_rhs = def_src;
Fixed.
>
> Thanks,
> Richard
>
Here is the v4 patch. OK for master?
Thanks.
H.J.
---
RTL DSE tracks redundant constant stores within a basic block. When RTL
loop invariant motion hoists a constant initialization out of the loop
into a separate basic block, the constant store value becomes unknown
within the original basic block. When recording store for RTL DSE, check
if the source register is set only once to a constant by a non-partial
unconditional load. If yes, record the constant as the constant store
source. It eliminates unrolled zero stores after memset 0 in a loop
where a vector register is used as the zero store source.
gcc/
PR rtl-optimization/105638
* df-core.cc (df_find_single_def_src): Moved and renamed from
find_single_def_src in loop-iv.cc. Change the argument to rtx
and use rtx_equal_p. Return null for partial or conditional
defs.
* df.h (df_find_single_def_src): New prototype.
* dse.cc (record_store): Use the constant source if the source
register is set only once.
* loop-iv.cc (find_single_def_src): Moved to df-core.cc.
(replace_single_def_regs): Replace find_single_def_src with
df_find_single_def_src.
gcc/testsuite/
PR rtl-optimization/105638
* g++.target/i386/pr105638.C: New test.
---
gcc/df-core.cc | 44 +++++++++++++++++++++++
gcc/df.h | 1 +
gcc/dse.cc | 8 +++++
gcc/loop-iv.cc | 45 +-----------------------
gcc/testsuite/g++.target/i386/pr105638.C | 44 +++++++++++++++++++++++
5 files changed, 98 insertions(+), 44 deletions(-)
create mode 100644 gcc/testsuite/g++.target/i386/pr105638.C
diff --git a/gcc/df-core.cc b/gcc/df-core.cc
index a901b84878f..e56d9bcf760 100644
--- a/gcc/df-core.cc
+++ b/gcc/df-core.cc
@@ -2009,6 +2009,50 @@ df_reg_used (rtx_insn *insn, rtx reg)
return df_find_use (insn, reg) != NULL;
}
+/* If REG has a single definition, return its known value, otherwise return
+ null. */
+
+rtx
+df_find_single_def_src (rtx reg)
+{
+ rtx src = NULL_RTX;
+
+ /* Don't look through unbounded number of single definition REG copies,
+ there might be loops for sources with uninitialized variables. */
+ for (int cnt = 0; cnt < 128; cnt++)
+ {
+ df_ref adef = DF_REG_DEF_CHAIN (REGNO (reg));
+ if (adef == NULL || DF_REF_NEXT_REG (adef) != NULL
+ || DF_REF_IS_ARTIFICIAL (adef)
+ || (DF_REF_FLAGS (adef)
+ & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
+ return NULL_RTX;
+
+ rtx set = single_set (DF_REF_INSN (adef));
+ if (set == NULL || !rtx_equal_p (SET_DEST (set), reg))
+ return NULL_RTX;
+
+ rtx note = find_reg_equal_equiv_note (DF_REF_INSN (adef));
+ if (note && function_invariant_p (XEXP (note, 0)))
+ {
+ src = XEXP (note, 0);
+ return src;
+ }
+ src = SET_SRC (set);
+
+ if (REG_P (src))
+ {
+ reg = src;
+ continue;
+ }
+ break;
+ }
+ if (!function_invariant_p (src))
+ return NULL_RTX;
+
+ return src;
+}
+
/*----------------------------------------------------------------------------
Debugging and printing functions.
diff --git a/gcc/df.h b/gcc/df.h
index bd329205d08..71e249ad20a 100644
--- a/gcc/df.h
+++ b/gcc/df.h
@@ -991,6 +991,7 @@ extern df_ref df_find_def (rtx_insn *, rtx);
extern bool df_reg_defined (rtx_insn *, rtx);
extern df_ref df_find_use (rtx_insn *, rtx);
extern bool df_reg_used (rtx_insn *, rtx);
+extern rtx df_find_single_def_src (rtx);
extern void df_worklist_dataflow (struct dataflow *,bitmap, int *, int);
extern void df_print_regset (FILE *file, const_bitmap r);
extern void df_print_word_regset (FILE *file, const_bitmap r);
diff --git a/gcc/dse.cc b/gcc/dse.cc
index 30c11cee034..994c60dc189 100644
--- a/gcc/dse.cc
+++ b/gcc/dse.cc
@@ -1508,6 +1508,14 @@ record_store (rtx body, bb_info_t bb_info)
if (tem && CONSTANT_P (tem))
const_rhs = tem;
+ else
+ {
+ /* If RHS is set only once to a constant, set CONST_RHS
+ to the constant. */
+ rtx def_src = df_find_single_def_src (rhs);
+ if (def_src != nullptr && CONSTANT_P (def_src))
+ const_rhs = def_src;
+ }
}
}
diff --git a/gcc/loop-iv.cc b/gcc/loop-iv.cc
index 0eafe7d2362..d639336445a 100644
--- a/gcc/loop-iv.cc
+++ b/gcc/loop-iv.cc
@@ -1378,49 +1378,6 @@ simple_rhs_p (rtx rhs)
}
}
-/* If REGNO has a single definition, return its known value, otherwise return
- null. */
-
-static rtx
-find_single_def_src (unsigned int regno)
-{
- rtx src = NULL_RTX;
-
- /* Don't look through unbounded number of single definition REG copies,
- there might be loops for sources with uninitialized variables. */
- for (int cnt = 0; cnt < 128; cnt++)
- {
- df_ref adef = DF_REG_DEF_CHAIN (regno);
- if (adef == NULL || DF_REF_NEXT_REG (adef) != NULL
- || DF_REF_IS_ARTIFICIAL (adef))
- return NULL_RTX;
-
- rtx set = single_set (DF_REF_INSN (adef));
- if (set == NULL || !REG_P (SET_DEST (set))
- || REGNO (SET_DEST (set)) != regno)
- return NULL_RTX;
-
- rtx note = find_reg_equal_equiv_note (DF_REF_INSN (adef));
- if (note && function_invariant_p (XEXP (note, 0)))
- {
- src = XEXP (note, 0);
- break;
- }
- src = SET_SRC (set);
-
- if (REG_P (src))
- {
- regno = REGNO (src);
- continue;
- }
- break;
- }
- if (!function_invariant_p (src))
- return NULL_RTX;
-
- return src;
-}
-
/* If any registers in *EXPR that have a single definition, try to replace
them with the known-equivalent values. */
@@ -1433,7 +1390,7 @@ replace_single_def_regs (rtx *expr)
{
rtx x = *iter;
if (REG_P (x))
- if (rtx new_x = find_single_def_src (REGNO (x)))
+ if (rtx new_x = df_find_single_def_src (x))
{
*expr = simplify_replace_rtx (*expr, x, new_x);
goto repeat;
diff --git a/gcc/testsuite/g++.target/i386/pr105638.C
b/gcc/testsuite/g++.target/i386/pr105638.C
new file mode 100644
index 00000000000..ff40a459de1
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr105638.C
@@ -0,0 +1,44 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-std=gnu++20 -O2 -march=skylake" } */
+/* { dg-final { scan-assembler-not "vpxor" } } */
+
+#include <stdint.h>
+#include <vector>
+#include <tr1/array>
+
+class FastBoard {
+public:
+ typedef std::pair<int, int> movescore_t;
+ typedef std::tr1::array<movescore_t, 24> scoredlist_t;
+
+protected:
+ std::vector<int> m_critical;
+
+ int m_boardsize;
+};
+
+class FastState {
+public:
+ FastBoard board;
+
+ int movenum;
+protected:
+ FastBoard::scoredlist_t scoredmoves;
+};
+
+class KoState : public FastState {
+private:
+ std::vector<uint64_t> ko_hash_history;
+ std::vector<uint64_t> hash_history;
+};
+
+class GameState : public KoState {
+public:
+ void foo ();
+private:
+ std::vector<KoState> game_history;
+};
+
+void GameState::foo() {
+ game_history.resize(movenum);
+}
--
2.36.1
