From: Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp>
This patch revises the previous implementation of constant synthesis.
First, changed to use define_split machine description pattern and to run
after reload pass, in order not to interfere some optimizations such as
the loop invariant motion.
Second, not only integer but floating-point is subject to processing.
Third, several new synthesis patterns - when the constant cannot fit into
a "MOVI Ax, simm12" instruction, but:
I. can be represented as a power of two minus one (eg. 32767, 65535 or
0x7fffffffUL)
=> "MOVI(.N) Ax, -1" + "SRLI Ax, Ax, 1 ... 31" (or "EXTUI")
II. is between -34816 and 34559
=> "MOVI(.N) Ax, -2048 ... 2047" + "ADDMI Ax, Ax, -32768 ... 32512"
III. (existing case) can fit into a signed 12-bit if the trailing zero bits
are stripped
=> "MOVI(.N) Ax, -2048 ... 2047" + "SLLI Ax, Ax, 1 ... 31"
The above sequences consist of 5 or 6 bytes and have latency of 2 clock cycles,
in contrast with "L32R Ax, <litpool>" (3 bytes and one clock latency, but may
suffer additional one clock pipeline stall and implementation-specific
InstRAM/ROM access penalty) plus 4 bytes of constant value.
In addition, 3-instructions synthesis patterns (8 or 9 bytes, 3 clock latency)
are also provided when optimizing for speed and L32R instruction has
considerable access penalty:
IV. 2-instructions synthesis (any of I ... III) followed by
"SLLI Ax, Ax, 1 ... 31"
V. 2-instructions synthesis followed by either "ADDX[248] Ax, Ax, Ax"
or "SUBX8 Ax, Ax, Ax" (multiplying by 3, 5, 7 or 9)
gcc/ChangeLog:
* config/xtensa/xtensa-protos.h (xtensa_constantsynth):
New prototype.
* config/xtensa/xtensa.cc (xtensa_emit_constantsynth,
xtensa_constantsynth_2insn, xtensa_constantsynth_rtx_SLLI,
xtensa_constantsynth_rtx_ADDSUBX, xtensa_constantsynth):
New backend functions that process the abovementioned logic.
(xtensa_emit_move_sequence): Revert the previous changes.
* config/xtensa/xtensa.md: New split patterns for integer
and floating-point, as the frontend part.
gcc/testsuite/ChangeLog:
* gcc.target/xtensa/constsynth_2insns.c: New.
* gcc.target/xtensa/constsynth_3insns.c: Ditto.
* gcc.target/xtensa/constsynth_double.c: Ditto.
---
gcc/config/xtensa/xtensa-protos.h | 1 +
gcc/config/xtensa/xtensa.cc | 133 +++++++++++++++---
gcc/config/xtensa/xtensa.md | 50 +++++++
.../gcc.target/xtensa/constsynth_2insns.c | 44 ++++++
.../gcc.target/xtensa/constsynth_3insns.c | 24 ++++
.../gcc.target/xtensa/constsynth_double.c | 11 ++
6 files changed, 247 insertions(+), 16 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/xtensa/constsynth_2insns.c
create mode 100644 gcc/testsuite/gcc.target/xtensa/constsynth_3insns.c
create mode 100644 gcc/testsuite/gcc.target/xtensa/constsynth_double.c
diff --git a/gcc/config/xtensa/xtensa-protos.h
b/gcc/config/xtensa/xtensa-protos.h
index 30e4b54394a9..c2fd750cd3ac 100644
--- a/gcc/config/xtensa/xtensa-protos.h
+++ b/gcc/config/xtensa/xtensa-protos.h
@@ -44,6 +44,7 @@ extern int xtensa_expand_block_move (rtx *);
extern int xtensa_expand_block_set_unrolled_loop (rtx *);
extern int xtensa_expand_block_set_small_loop (rtx *);
extern void xtensa_split_operand_pair (rtx *, machine_mode);
+extern int xtensa_constantsynth (rtx, HOST_WIDE_INT);
extern int xtensa_emit_move_sequence (rtx *, machine_mode);
extern rtx xtensa_copy_incoming_a7 (rtx);
extern void xtensa_expand_nonlocal_goto (rtx *);
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index 597a36e1a973..3477e983592a 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -1037,6 +1037,123 @@ xtensa_split_operand_pair (rtx operands[4],
machine_mode mode)
}
+/* Try to emit insns to load srcval (that cannot fit into signed 12-bit)
+ into dst with synthesizing a such constant value from a sequence of
+ load-immediate / arithmetic ones, instead of a L32R instruction
+ (plus a constant in litpool). */
+
+static void
+xtensa_emit_constantsynth (rtx dst, enum rtx_code code,
+ HOST_WIDE_INT imm0, HOST_WIDE_INT imm1,
+ rtx (*gen_op)(rtx, HOST_WIDE_INT),
+ HOST_WIDE_INT imm2)
+{
+ gcc_assert (REG_P (dst));
+ emit_move_insn (dst, GEN_INT (imm0));
+ emit_move_insn (dst, gen_rtx_fmt_ee (code, SImode,
+ dst, GEN_INT (imm1)));
+ if (gen_op)
+ emit_move_insn (dst, gen_op (dst, imm2));
+}
+
+static int
+xtensa_constantsynth_2insn (rtx dst, HOST_WIDE_INT srcval,
+ rtx (*gen_op)(rtx, HOST_WIDE_INT),
+ HOST_WIDE_INT op_imm)
+{
+ int shift = exact_log2 (srcval + 1);
+
+ if (IN_RANGE (shift, 1, 31))
+ {
+ xtensa_emit_constantsynth (dst, LSHIFTRT, -1, 32 - shift,
+ gen_op, op_imm);
+ return 1;
+ }
+
+ if (IN_RANGE (srcval, (-2048 - 32768), (2047 + 32512)))
+ {
+ HOST_WIDE_INT imm0, imm1;
+
+ if (srcval < -32768)
+ imm1 = -32768;
+ else if (srcval > 32512)
+ imm1 = 32512;
+ else
+ imm1 = srcval & ~255;
+ imm0 = srcval - imm1;
+ if (TARGET_DENSITY && imm1 < 32512 && IN_RANGE (imm0, 224, 255))
+ imm0 -= 256, imm1 += 256;
+ xtensa_emit_constantsynth (dst, PLUS, imm0, imm1, gen_op, op_imm);
+ return 1;
+ }
+
+ shift = ctz_hwi (srcval);
+ if (xtensa_simm12b (srcval >> shift))
+ {
+ xtensa_emit_constantsynth (dst, ASHIFT, srcval >> shift, shift,
+ gen_op, op_imm);
+ return 1;
+ }
+
+ return 0;
+}
+
+static rtx
+xtensa_constantsynth_rtx_SLLI (rtx reg, HOST_WIDE_INT imm)
+{
+ return gen_rtx_ASHIFT (SImode, reg, GEN_INT (imm));
+}
+
+static rtx
+xtensa_constantsynth_rtx_ADDSUBX (rtx reg, HOST_WIDE_INT imm)
+{
+ return imm == 7
+ ? gen_rtx_MINUS (SImode, gen_rtx_ASHIFT (SImode, reg, GEN_INT (3)),
+ reg)
+ : gen_rtx_PLUS (SImode, gen_rtx_ASHIFT (SImode, reg,
+ GEN_INT (floor_log2 (imm -
1))),
+ reg);
+}
+
+int
+xtensa_constantsynth (rtx dst, HOST_WIDE_INT srcval)
+{
+ /* No need for synthesizing for what fits into MOVI instruction. */
+ if (xtensa_simm12b (srcval))
+ return 0;
+
+ /* 2-insns substitution. */
+ if ((optimize_size || (optimize && xtensa_extra_l32r_costs >= 1))
+ && xtensa_constantsynth_2insn (dst, srcval, NULL, 0))
+ return 1;
+
+ /* 3-insns substitution. */
+ if (optimize > 1 && !optimize_size && xtensa_extra_l32r_costs >= 2)
+ {
+ int shift, divisor;
+
+ /* 2-insns substitution followed by SLLI. */
+ shift = ctz_hwi (srcval);
+ if (IN_RANGE (shift, 1, 31) &&
+ xtensa_constantsynth_2insn (dst, srcval >> shift,
+ xtensa_constantsynth_rtx_SLLI,
+ shift))
+ return 1;
+
+ /* 2-insns substitution followed by ADDX[248] or SUBX8. */
+ if (TARGET_ADDX)
+ for (divisor = 3; divisor <= 9; divisor += 2)
+ if (srcval % divisor == 0 &&
+ xtensa_constantsynth_2insn (dst, srcval / divisor,
+ xtensa_constantsynth_rtx_ADDSUBX,
+ divisor))
+ return 1;
+ }
+
+ return 0;
+}
+
+
/* Emit insns to move operands[1] into operands[0].
Return 1 if we have written out everything that needs to be done to
do the move. Otherwise, return 0 and the caller will emit the move
@@ -1074,22 +1191,6 @@ xtensa_emit_move_sequence (rtx *operands, machine_mode
mode)
if (! TARGET_AUTO_LITPOOLS && ! TARGET_CONST16)
{
- /* Try to emit MOVI + SLLI sequence, that is smaller
- than L32R + literal. */
- if (optimize_size && mode == SImode && CONST_INT_P (src)
- && register_operand (dst, mode))
- {
- HOST_WIDE_INT srcval = INTVAL (src);
- int shift = ctz_hwi (srcval);
-
- if (xtensa_simm12b (srcval >> shift))
- {
- emit_move_insn (dst, GEN_INT (srcval >> shift));
- emit_insn (gen_ashlsi3_internal (dst, dst, GEN_INT (shift)));
- return 1;
- }
- }
-
src = force_const_mem (SImode, src);
operands[1] = src;
}
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index f6c6be4af242..d806d43d1297 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -937,6 +937,19 @@
(set_attr "mode" "SI")
(set_attr "length" "2,2,2,2,2,2,3,3,3,3,6,3,3,3,3,3")])
+(define_split
+ [(set (match_operand:SI 0 "register_operand")
+ (match_operand:SI 1 "constantpool_operand"))]
+ "! optimize_debug && reload_completed"
+ [(const_int 0)]
+{
+ rtx x = avoid_constant_pool_reference (operands[1]);
+ if (! CONST_INT_P (x))
+ FAIL;
+ if (! xtensa_constantsynth (operands[0], INTVAL (x)))
+ emit_move_insn (operands[0], x);
+})
+
;; 16-bit Integer moves
(define_expand "movhi"
@@ -1139,6 +1152,43 @@
(set_attr "mode" "SF")
(set_attr "length" "3")])
+(define_split
+ [(set (match_operand:SF 0 "register_operand")
+ (match_operand:SF 1 "constantpool_operand"))]
+ "! optimize_debug && reload_completed"
+ [(const_int 0)]
+{
+ int i = 0;
+ rtx x = XEXP (operands[1], 0);
+ long l[2];
+ if (GET_CODE (x) == SYMBOL_REF
+ && CONSTANT_POOL_ADDRESS_P (x))
+ x = get_pool_constant (x);
+ else if (GET_CODE (x) == CONST)
+ {
+ x = XEXP (x, 0);
+ gcc_assert (GET_CODE (x) == PLUS
+ && GET_CODE (XEXP (x, 0)) == SYMBOL_REF
+ && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))
+ && CONST_INT_P (XEXP (x, 1)));
+ i = INTVAL (XEXP (x, 1));
+ gcc_assert (i == 0 || i == 4);
+ i /= 4;
+ x = get_pool_constant (XEXP (x, 0));
+ }
+ else
+ gcc_unreachable ();
+ if (GET_MODE (x) == SFmode)
+ REAL_VALUE_TO_TARGET_SINGLE (*CONST_DOUBLE_REAL_VALUE (x), l[0]);
+ else if (GET_MODE (x) == DFmode)
+ REAL_VALUE_TO_TARGET_DOUBLE (*CONST_DOUBLE_REAL_VALUE (x), l);
+ else
+ FAIL;
+ x = gen_rtx_REG (SImode, REGNO (operands[0]));
+ if (! xtensa_constantsynth (x, l[i]))
+ emit_move_insn (x, GEN_INT (l[i]));
+})
+
;; 64-bit floating point moves
(define_expand "movdf"
diff --git a/gcc/testsuite/gcc.target/xtensa/constsynth_2insns.c
b/gcc/testsuite/gcc.target/xtensa/constsynth_2insns.c
new file mode 100644
index 000000000000..43c85a25086a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/xtensa/constsynth_2insns.c
@@ -0,0 +1,44 @@
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+int test_0(void)
+{
+ return 4095;
+}
+
+int test_1(void)
+{
+ return 2147483647;
+}
+
+int test_2(void)
+{
+ return -34816;
+}
+
+int test_3(void)
+{
+ return -2049;
+}
+
+int test_4(void)
+{
+ return 2048;
+}
+
+int test_5(void)
+{
+ return 34559;
+}
+
+int test_6(void)
+{
+ return 43680;
+}
+
+void test_7(int *p)
+{
+ *p = -1432354816;
+}
+
+/* { dg-final { scan-assembler-not "l32r" } } */
diff --git a/gcc/testsuite/gcc.target/xtensa/constsynth_3insns.c
b/gcc/testsuite/gcc.target/xtensa/constsynth_3insns.c
new file mode 100644
index 000000000000..f3c4a1c7c15b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/xtensa/constsynth_3insns.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mextra-l32r-costs=3" } */
+
+int test_0(void)
+{
+ return 134217216;
+}
+
+int test_1(void)
+{
+ return -27604992;
+}
+
+int test_2(void)
+{
+ return -162279;
+}
+
+void test_3(int *p)
+{
+ *p = 192437;
+}
+
+/* { dg-final { scan-assembler-not "l32r" } } */
diff --git a/gcc/testsuite/gcc.target/xtensa/constsynth_double.c
b/gcc/testsuite/gcc.target/xtensa/constsynth_double.c
new file mode 100644
index 000000000000..890ca5047801
--- /dev/null
+++ b/gcc/testsuite/gcc.target/xtensa/constsynth_double.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+void test(unsigned int count, double array[])
+{
+ unsigned int i;
+ for (i = 0; i < count; ++i)
+ array[i] = 1.0;
+}
+
+/* { dg-final { scan-assembler-not "l32r" } } */
--
2.30.2
