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Commit 04f307cb by Richard Sandiford
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aarch64: Add SVE support for -mlow-precision-div 

SVE was missing support for -mlow-precision-div, which meant that
-march=armv8.2-a+sve -mlow-precision-div could cause a performance
regression compared to -march=armv8.2-a -mlow-precision-div.

I ended up doing this much later than originally intended, sorry...

2020-02-21  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64.c (aarch64_emit_mult): New function.
	(aarch64_emit_approx_div): Add SVE support.  Use aarch64_emit_mult
	instead of emitting multiplication instructions directly.
	* config/aarch64/iterators.md (SVE_COND_FP_BINARY_OPTAB): New iterator.
	* config/aarch64/aarch64-sve.md (div<mode>3, @aarch64_frecpe<mode>)
	(@aarch64_frecps<mode>): New expanders.

gcc/testsuite/
	* gcc.target/aarch64/sve/recip_1.c: New test.
	* gcc.target/aarch64/sve/recip_1_run.c: Likewise.
	* gcc.target/aarch64/sve/recip_2.c: Likewise.
	* gcc.target/aarch64/sve/recip_2_run.c: Likewise.
parent d87778ed
Showing with 207 additions and 4 deletions
gcc/ChangeLog
2020-02-21 Richard Sandiford <richard.sandiford@arm.com>
* config/aarch64/aarch64.c (aarch64_emit_mult): New function.
(aarch64_emit_approx_div): Add SVE support. Use aarch64_emit_mult
instead of emitting multiplication instructions directly.
* config/aarch64/iterators.md (SVE_COND_FP_BINARY_OPTAB): New iterator.
* config/aarch64/aarch64-sve.md (div<mode>3, @aarch64_frecpe<mode>)
(@aarch64_frecps<mode>): New expanders.
2020-02-21 Richard Sandiford <richard.sandiford@arm.com>
* config/aarch64/aarch64-protos.h (AARCH64_APPROX_MODE): Operate
on and produce uint64_ts rather than ints.
(AARCH64_APPROX_NONE, AARCH64_APPROX_ALL): Change to uint64_ts.
......
gcc/config/aarch64/aarch64-sve.md
......@@ -99,6 +99,7 @@
;; ---- [FP] Subtraction
;; ---- [FP] Absolute difference
;; ---- [FP] Multiplication
;; ---- [FP] Division
;; ---- [FP] Binary logical operations
;; ---- [FP] Sign copying
;; ---- [FP] Maximum and minimum
......@@ -4719,7 +4720,7 @@
(const_int SVE_RELAXED_GP)
(match_operand:SVE_FULL_F 1 "<sve_pred_fp_rhs1_operand>")
(match_operand:SVE_FULL_F 2 "<sve_pred_fp_rhs2_operand>")]
SVE_COND_FP_BINARY))]
SVE_COND_FP_BINARY_OPTAB))]
"TARGET_SVE"
{
operands[3] = aarch64_ptrue_reg (<VPRED>mode);
......@@ -5456,6 +5457,47 @@
)
;; -------------------------------------------------------------------------
;; ---- [FP] Division
;; -------------------------------------------------------------------------
;; The patterns in this section are synthetic.
;; -------------------------------------------------------------------------
(define_expand "div<mode>3"
[(set (match_operand:SVE_FULL_F 0 "register_operand")
(unspec:SVE_FULL_F
[(match_dup 3)
(const_int SVE_RELAXED_GP)
(match_operand:SVE_FULL_F 1 "nonmemory_operand")
(match_operand:SVE_FULL_F 2 "register_operand")]
UNSPEC_COND_FDIV))]
"TARGET_SVE"
{
if (aarch64_emit_approx_div (operands[0], operands[1], operands[2]))
DONE;
operands[1] = force_reg (<MODE>mode, operands[1]);
operands[3] = aarch64_ptrue_reg (<VPRED>mode);
}
)
(define_expand "@aarch64_frecpe<mode>"
[(set (match_operand:SVE_FULL_F 0 "register_operand")
(unspec:SVE_FULL_F
[(match_operand:SVE_FULL_F 1 "register_operand")]
UNSPEC_FRECPE))]
"TARGET_SVE"
)
(define_expand "@aarch64_frecps<mode>"
[(set (match_operand:SVE_FULL_F 0 "register_operand")
(unspec:SVE_FULL_F
[(match_operand:SVE_FULL_F 1 "register_operand")
(match_operand:SVE_FULL_F 2 "register_operand")]
UNSPEC_FRECPS))]
"TARGET_SVE"
)
;; -------------------------------------------------------------------------
;; ---- [FP] Binary logical operations
;; -------------------------------------------------------------------------
;; Includes
......
gcc/config/aarch64/aarch64.c
......@@ -12739,6 +12739,25 @@ aarch64_builtin_reciprocal (tree fndecl)
gcc_unreachable ();
}
/* Emit code to perform the floating-point operation:
DST = SRC1 * SRC2
where all three operands are already known to be registers.
If the operation is an SVE one, PTRUE is a suitable all-true
predicate. */
static void
aarch64_emit_mult (rtx dst, rtx ptrue, rtx src1, rtx src2)
{
if (ptrue)
emit_insn (gen_aarch64_pred (UNSPEC_COND_FMUL, GET_MODE (dst),
dst, ptrue, src1, src2,
gen_int_mode (SVE_RELAXED_GP, SImode)));
else
emit_set_insn (dst, gen_rtx_MULT (GET_MODE (dst), src1, src2));
}
/* Emit instruction sequence to compute either the approximate square root
or its approximate reciprocal, depending on the flag RECP, and return
whether the sequence was emitted or not. */
......@@ -12857,6 +12876,10 @@ aarch64_emit_approx_div (rtx quo, rtx num, rtx den)
if (!TARGET_SIMD && VECTOR_MODE_P (mode))
return false;
rtx pg = NULL_RTX;
if (aarch64_sve_mode_p (mode))
pg = aarch64_ptrue_reg (aarch64_sve_pred_mode (mode));
/* Estimate the approximate reciprocal. */
rtx xrcp = gen_reg_rtx (mode);
emit_insn (gen_aarch64_frecpe (mode, xrcp, den));
......@@ -12876,7 +12899,7 @@ aarch64_emit_approx_div (rtx quo, rtx num, rtx den)
emit_insn (gen_aarch64_frecps (mode, xtmp, xrcp, den));
if (iterations > 0)
emit_set_insn (xrcp, gen_rtx_MULT (mode, xrcp, xtmp));
aarch64_emit_mult (xrcp, pg, xrcp, xtmp);
}
if (num != CONST1_RTX (mode))
......@@ -12884,11 +12907,11 @@ aarch64_emit_approx_div (rtx quo, rtx num, rtx den)
/* As the approximate reciprocal of DEN is already calculated, only
calculate the approximate division when NUM is not 1.0. */
rtx xnum = force_reg (mode, num);
emit_set_insn (xrcp, gen_rtx_MULT (mode, xrcp, xnum));
aarch64_emit_mult (xrcp, pg, xrcp, xnum);
}
/* Finalize the approximation. */
emit_set_insn (quo, gen_rtx_MULT (mode, xrcp, xtmp));
aarch64_emit_mult (quo, pg, xrcp, xtmp);
return true;
}
......
gcc/config/aarch64/iterators.md
......@@ -2291,6 +2291,17 @@
UNSPEC_COND_FMULX
UNSPEC_COND_FSUB])
;; Same as SVE_COND_FP_BINARY, but without codes that have a dedicated
;; <optab><mode>3 expander.
(define_int_iterator SVE_COND_FP_BINARY_OPTAB [UNSPEC_COND_FADD
UNSPEC_COND_FMAX
UNSPEC_COND_FMAXNM
UNSPEC_COND_FMIN
UNSPEC_COND_FMINNM
UNSPEC_COND_FMUL
UNSPEC_COND_FMULX
UNSPEC_COND_FSUB])
(define_int_iterator SVE_COND_FP_BINARY_INT [UNSPEC_COND_FSCALE])
(define_int_iterator SVE_COND_FP_ADD [UNSPEC_COND_FADD])
......
gcc/testsuite/ChangeLog
2020-02-21 Richard Sandiford <richard.sandiford@arm.com>
* gcc.target/aarch64/sve/recip_1.c: New test.
* gcc.target/aarch64/sve/recip_1_run.c: Likewise.
* gcc.target/aarch64/sve/recip_2.c: Likewise.
* gcc.target/aarch64/sve/recip_2_run.c: Likewise.
2020-02-20 Martin Sebor <msebor@redhat.com>
PR c++/93801
......
gcc/testsuite/gcc.target/aarch64/sve/recip_1.c 0 → 100644
/* { dg-options "-Ofast -mlow-precision-div" } */
#define DEF_LOOP(TYPE) \
void \
test_##TYPE (TYPE *x, int n) \
{ \
for (int i = 0; i < n; ++i) \
x[i] = (TYPE) 1 / x[i]; \
}
#define TEST_ALL(T) \
T (_Float16) \
T (float) \
T (double)
TEST_ALL (DEF_LOOP)
/* { dg-final { scan-assembler-not {\tfrecpe\tz[0-9]+\.h} } } */
/* { dg-final { scan-assembler-not {\tfrecps\tz[0-9]+\.h} } } */
/* { dg-final { scan-assembler-times {\tfmul\tz[0-9]+\.s} 1 } } */
/* { dg-final { scan-assembler-times {\tfrecpe\tz[0-9]+\.s} 1 } } */
/* { dg-final { scan-assembler-times {\tfrecps\tz[0-9]+\.s} 1 } } */
/* { dg-final { scan-assembler-times {\tfmul\tz[0-9]+\.d} 2 } } */
/* { dg-final { scan-assembler-times {\tfrecpe\tz[0-9]+\.d} 1 } } */
/* { dg-final { scan-assembler-times {\tfrecps\tz[0-9]+\.d} 2 } } */
gcc/testsuite/gcc.target/aarch64/sve/recip_1_run.c 0 → 100644
/* { dg-do run { target aarch64_sve_hw } } */
/* { dg-options "-Ofast -mlow-precision-div" } */
#include "recip_1.c"
#define N 77
#define TEST_LOOP(TYPE) \
{ \
TYPE a[N]; \
for (int i = 0; i < N; ++i) \
a[i] = i + 1; \
test_##TYPE (a, N); \
for (int i = 0; i < N; ++i) \
{ \
double diff = a[i] - 1.0 / (i + 1); \
if (__builtin_fabs (diff) > 0x1.0p-8) \
__builtin_abort (); \
} \
}
int
main (void)
{
TEST_ALL (TEST_LOOP);
return 0;
}
gcc/testsuite/gcc.target/aarch64/sve/recip_2.c 0 → 100644
/* { dg-options "-Ofast -mlow-precision-div" } */
#define DEF_LOOP(TYPE) \
void \
test_##TYPE (TYPE *restrict x, TYPE *restrict y, int n) \
{ \
for (int i = 0; i < n; ++i) \
x[i] /= y[i]; \
}
#define TEST_ALL(T) \
T (_Float16) \
T (float) \
T (double)
TEST_ALL (DEF_LOOP)
/* { dg-final { scan-assembler-not {\tfrecpe\tz[0-9]+\.h} } } */
/* { dg-final { scan-assembler-not {\tfrecps\tz[0-9]+\.h} } } */
/* { dg-final { scan-assembler-times {\tfmul\tz[0-9]+\.s} 2 } } */
/* { dg-final { scan-assembler-times {\tfrecpe\tz[0-9]+\.s} 1 } } */
/* { dg-final { scan-assembler-times {\tfrecps\tz[0-9]+\.s} 1 } } */
/* { dg-final { scan-assembler-times {\tfmul\tz[0-9]+\.d} 3 } } */
/* { dg-final { scan-assembler-times {\tfrecpe\tz[0-9]+\.d} 1 } } */
/* { dg-final { scan-assembler-times {\tfrecps\tz[0-9]+\.d} 2 } } */
gcc/testsuite/gcc.target/aarch64/sve/recip_2_run.c 0 → 100644
/* { dg-do run { target aarch64_sve_hw } } */
/* { dg-options "-Ofast -mlow-precision-div" } */
#include "recip_2.c"
#define N 77
#define TEST_LOOP(TYPE) \
{ \
TYPE a[N], b[N]; \
for (int i = 0; i < N; ++i) \
{ \
a[i] = i + 11; \
b[i] = i + 1; \
} \
test_##TYPE (a, b, N); \
for (int i = 0; i < N; ++i) \
{ \
double diff = a[i] - (i + 11.0) / (i + 1); \
if (__builtin_fabs (diff) > 0x1.0p-8) \
__builtin_abort (); \
} \
}
int
main (void)
{
TEST_ALL (TEST_LOOP);
return 0;
}
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