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Re: [PATCH 2/3] [ARM] Refactor costs calculation for MEM.
On 13 September 2017 at 10:02, Kyrill Tkachov
<kyrylo.tkachov@foss.arm.com> wrote:
> Hi Charles,
>
> On 12/09/17 09:34, charles.baylis@linaro.org wrote:
>>
>> From: Charles Baylis <charles.baylis@linaro.org>
>>
>> This patch moves the calculation of costs for MEM into a
>> separate function, and reforms the calculation into two
>> parts. Firstly any additional cost of the addressing mode
>> is calculated, and then the cost of the memory access itself
>> is added.
>>
>> In this patch, the calculation of the cost of the addressing
>> mode is left as a placeholder, to be added in a subsequent
>> patch.
>>
>
> Can you please mention how has this series been tested?
> A bootstrap and test run on arm-none-linux-gnueabihf is required at least.
It has been tested with make check on arm-unknown-linux-gnueabihf with
no regressions. I've successfully bootstrapped the next spin.
> Also, do you have any benchmarking results for this?
> I agree that generating the addressing modes in the new tests is desirable.
> So I'm not objecting to the goal of this patch, but a check to make sure
> that this doesn't regress SPEC
> would be great. Further comments on the patch inline.
SPEC2006 scores are unaffected by this patch on Cortex-A57.
>> +/* Helper function for arm_rtx_costs_internal. Calculates the cost of a
>> MEM,
>> + considering the costs of the addressing mode and memory access
>> + separately. */
>> +static bool
>> +arm_mem_costs (rtx x, const struct cpu_cost_table *extra_cost,
>> + int *cost, bool speed_p)
>> +{
>> + machine_mode mode = GET_MODE (x);
>> + if (flag_pic
>> + && GET_CODE (XEXP (x, 0)) == PLUS
>> + && will_be_in_index_register (XEXP (XEXP (x, 0), 1)))
>> + /* This will be split into two instructions. Add the cost of the
>> + additional instruction here. The cost of the memory access is
>> computed
>> + below. See arm.md:calculate_pic_address. */
>> + *cost = COSTS_N_INSNS (1);
>> + else
>> + *cost = 0;
>
>
> For speed_p we want the size cost of the insn (COSTS_N_INSNS (1) for a each
> insn)
> plus the appropriate field in extra_cost. So you should unconditionally
> initialise the cost
> to COSTS_N_INSNS (1), conditionally increment it by COSTS_N_INSNS (1) with
> the condition above.
OK. I also have to subtract that COSTS_N_INSNS (1) in the if (speed_p)
part because the cost of a single bus transfer is included in that
initial cost.
>> +
>> + /* Calculate cost of the addressing mode. */
>> + if (speed_p)
>> + {
>> + /* TODO: Add table-driven costs for addressing modes. (See patch
>> 2) */
>> + }
>
>
> You mean "patch 3". I recommend you just remove this conditional from this
> patch and add the logic
> in patch 3 entirely.
OK.
>> +
>> + /* Calculate cost of memory access. */
>> + if (speed_p)
>> + {
>> + /* data transfer is transfer size divided by bus width. */
>> + int bus_width_bytes = current_tune->bus_width / 4;
>
>
> This should be bus_width / BITS_PER_UNIT to get the size in bytes.
> BITS_PER_UNIT is 8 though, so you'll have to double check to make sure the
> cost calculation and generated code is still appropriate.
Oops, I changed the units around and messed this up. I'll fix this.
>> + *cost += CEIL (GET_MODE_SIZE (mode), bus_width_bytes);
>> + *cost += extra_cost->ldst.load;
>> + }
>> + else
>> + {
>> + *cost += COSTS_N_INSNS (1);
>> + }
>
> Given my first comment above this else would be deleted.
OK
From f81e1d3212475a3dc7aaeb8cb3171c6defd40687 Mon Sep 17 00:00:00 2001
From: Charles Baylis <charles.baylis@linaro.org>
Date: Wed, 8 Feb 2017 16:52:10 +0000
Subject: [PATCH 2/3] [ARM] Refactor costs calculation for MEM.
This patch moves the calculation of costs for MEM into a
separate function, and reforms the calculation into two
parts. Firstly any additional cost of the addressing mode
is calculated, and then the cost of the memory access itself
is added.
In this patch, the calculation of the cost of the addressing
mode is left as a placeholder, to be added in a subsequent
patch.
gcc/ChangeLog:
<date> Charles Baylis <charles.baylis@linaro.org>
* config/arm/arm.c (arm_mem_costs): New function.
(arm_rtx_costs_internal): Use arm_mem_costs.
gcc/testsuite/ChangeLog:
<date> Charles Baylis <charles.baylis@linaro.org>
* gcc.target/arm/addr-modes-float.c: New test.
* gcc.target/arm/addr-modes-int.c: New test.
* gcc.target/arm/addr-modes.h: New header.
Change-Id: I99e93406ea39ee31f71c7bf428ad3e127b7a618e
---
gcc/config/arm/arm.c | 60 ++++++++++++++-----------
gcc/testsuite/gcc.target/arm/addr-modes-float.c | 42 +++++++++++++++++
gcc/testsuite/gcc.target/arm/addr-modes-int.c | 46 +++++++++++++++++++
gcc/testsuite/gcc.target/arm/addr-modes.h | 53 ++++++++++++++++++++++
4 files changed, 176 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/arm/addr-modes-float.c
create mode 100644 gcc/testsuite/gcc.target/arm/addr-modes-int.c
create mode 100644 gcc/testsuite/gcc.target/arm/addr-modes.h
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 32001e5..64230b8 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -9228,8 +9228,41 @@ arm_unspec_cost (rtx x, enum rtx_code /* outer_code */, bool speed_p, int *cost)
} \
while (0);
+/* Helper function for arm_rtx_costs_internal. Calculates the cost of a MEM,
+ considering the costs of the addressing mode and memory access
+ separately. */
+static bool
+arm_mem_costs (rtx x, const struct cpu_cost_table *extra_cost,
+ int *cost, bool speed_p)
+{
+ machine_mode mode = GET_MODE (x);
+
+ *cost = COSTS_N_INSNS (1);
+
+ if (flag_pic
+ && GET_CODE (XEXP (x, 0)) == PLUS
+ && will_be_in_index_register (XEXP (XEXP (x, 0), 1)))
+ /* This will be split into two instructions. Add the cost of the
+ additional instruction here. The cost of the memory access is computed
+ below. See arm.md:calculate_pic_address. */
+ *cost += COSTS_N_INSNS (1);
+
+ /* Calculate cost of memory access. */
+ if (speed_p)
+ {
+ /* data transfer is transfer size divided by bus width. */
+ int bus_width_bytes = current_tune->bus_width / BITS_PER_UNIT;
+ int num_transfers = CEIL (GET_MODE_SIZE (mode), bus_width_bytes);
+ /* first transfer included in initial cost */
+ *cost += COSTS_N_INSNS (num_transfers - 1);
+ *cost += extra_cost->ldst.load;
+ }
+
+ return true;
+}
+
/* RTX costs. Make an estimate of the cost of executing the operation
- X, which is contained with an operation with code OUTER_CODE.
+ X, which is contained within an operation with code OUTER_CODE.
SPEED_P indicates whether the cost desired is the performance cost,
or the size cost. The estimate is stored in COST and the return
value is TRUE if the cost calculation is final, or FALSE if the
@@ -9308,30 +9341,7 @@ arm_rtx_costs_internal (rtx x, enum rtx_code code, enum rtx_code outer_code,
return false;
case MEM:
- /* A memory access costs 1 insn if the mode is small, or the address is
- a single register, otherwise it costs one insn per word. */
- if (REG_P (XEXP (x, 0)))
- *cost = COSTS_N_INSNS (1);
- else if (flag_pic
- && GET_CODE (XEXP (x, 0)) == PLUS
- && will_be_in_index_register (XEXP (XEXP (x, 0), 1)))
- /* This will be split into two instructions.
- See arm.md:calculate_pic_address. */
- *cost = COSTS_N_INSNS (2);
- else
- *cost = COSTS_N_INSNS (ARM_NUM_REGS (mode));
-
- /* For speed optimizations, add the costs of the address and
- accessing memory. */
- if (speed_p)
-#ifdef NOT_YET
- *cost += (extra_cost->ldst.load
- + arm_address_cost (XEXP (x, 0), mode,
- ADDR_SPACE_GENERIC, speed_p));
-#else
- *cost += extra_cost->ldst.load;
-#endif
- return true;
+ return arm_mem_costs (x, extra_cost, cost, speed_p);
case PARALLEL:
{
diff --git a/gcc/testsuite/gcc.target/arm/addr-modes-float.c b/gcc/testsuite/gcc.target/arm/addr-modes-float.c
new file mode 100644
index 0000000..3b4235c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/addr-modes-float.c
@@ -0,0 +1,42 @@
+/* { dg-options "-O2" } */
+/* { dg-add-options arm_neon } */
+/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-do compile } */
+
+#include <arm_neon.h>
+
+#include "addr-modes.h"
+
+POST_STORE(float)
+/* { dg-final { scan-assembler "vstmia.32" } } */
+POST_STORE(double)
+/* { dg-final { scan-assembler "vstmia.64" } } */
+
+POST_LOAD(float)
+/* { dg-final { scan-assembler "vldmia.32" } } */
+POST_LOAD(double)
+/* { dg-final { scan-assembler "vldmia.64" } } */
+
+POST_STORE_VEC (int8_t, int8x8_t, vst1_s8)
+/* { dg-final { scan-assembler "vst1.8\t\{.*\}, \\\[r\[0-9\]+\\\]!" } } */
+POST_STORE_VEC (int8_t, int8x16_t, vst1q_s8)
+/* { dg-final { scan-assembler "vst1.8\t\{.*\[-,\]d.*\}, \\\[r\[0-9\]+\\\]!" } } */
+
+POST_STORE_VEC (int8_t, int8x8x2_t, vst2_s8)
+/* { dg-final { scan-assembler "vst2.8\t\{.*\}, \\\[r\[0-9\]+\\\]!" } } */
+POST_STORE_VEC (int8_t, int8x16x2_t, vst2q_s8)
+/* { dg-final { scan-assembler "vst2.8\t\{.*-d.*\}, \\\[r\[0-9\]+\\\]!" } } */
+
+POST_STORE_VEC (int8_t, int8x8x3_t, vst3_s8)
+/* { dg-final { scan-assembler "vst3.8\t\{.*\}, \\\[r\[0-9\]+\\\]!" } } */
+POST_STORE_VEC (int8_t, int8x16x3_t, vst3q_s8)
+/* { dg-final { scan-assembler "vst3.8\t\{d\[02468\], d\[02468\], d\[02468\]\}, \\\[r\[0-9\]+\\\]!" } } */
+/* { dg-final { scan-assembler "vst3.8\t\{d\[13579\], d\[13579\], d\[13579\]\}, \\\[r\[0-9\]+\\\]!" { xfail *-*-* } } } */
+
+POST_STORE_VEC (int8_t, int8x8x4_t, vst4_s8)
+/* { dg-final { scan-assembler "vst4.8\t\{.*\}, \\\[r\[0-9\]+\\\]!" } } */
+POST_STORE_VEC (int8_t, int8x16x4_t, vst4q_s8)
+/* { dg-final { scan-assembler "vst4.8\t\{d\[02468\], d\[02468\], d\[02468\], d\[02468\]\}, \\\[r\[0-9\]+\\\]!" } } */
+/* { dg-final { scan-assembler "vst4.8\t\{d\[13579\], d\[13579\], d\[13579\], d\[13579\]\}, \\\[r\[0-9\]+\\\]!" { xfail *-*-* } } } */
+
+/* { dg-final { scan-assembler-not "add" { xfail *-*-* } } } */
diff --git a/gcc/testsuite/gcc.target/arm/addr-modes-int.c b/gcc/testsuite/gcc.target/arm/addr-modes-int.c
new file mode 100644
index 0000000..e3e1e6a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/addr-modes-int.c
@@ -0,0 +1,46 @@
+/* { dg-options "-O2 -march=armv7-a" } */
+/* { dg-add-options arm_neon } */
+/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-do compile } */
+
+#include "addr-modes.h"
+
+typedef long long ll;
+
+PRE_STORE(char)
+/* { dg-final { scan-assembler "strb.*#1]!" } } */
+PRE_STORE(short)
+/* { dg-final { scan-assembler "strh.*#2]!" } } */
+PRE_STORE(int)
+/* { dg-final { scan-assembler "str.*#4]!" } } */
+PRE_STORE(ll)
+/* { dg-final { scan-assembler "strd.*#8]!" } } */
+
+POST_STORE(char)
+/* { dg-final { scan-assembler "strb.*], #1" } } */
+POST_STORE(short)
+/* { dg-final { scan-assembler "strh.*], #2" } } */
+POST_STORE(int)
+/* { dg-final { scan-assembler "str.*], #4" } } */
+POST_STORE(ll)
+/* { dg-final { scan-assembler "strd.*], #8" } } */
+
+PRE_LOAD(char)
+/* { dg-final { scan-assembler "ldrb.*#1]!" } } */
+PRE_LOAD(short)
+/* { dg-final { scan-assembler "ldrsh.*#2]!" } } */
+PRE_LOAD(int)
+/* { dg-final { scan-assembler "ldr.*#4]!" } } */
+PRE_LOAD(ll)
+/* { dg-final { scan-assembler "ldrd.*#8]!" } } */
+
+POST_LOAD(char)
+/* { dg-final { scan-assembler "ldrb.*], #1" } } */
+POST_LOAD(short)
+/* { dg-final { scan-assembler "ldrsh.*], #2" } } */
+POST_LOAD(int)
+/* { dg-final { scan-assembler "ldr.*], #4" } } */
+POST_LOAD(ll)
+/* { dg-final { scan-assembler "ldrd.*], #8" } } */
+
+/* { dg-final { scan-assembler-not "\tadd" } } */
diff --git a/gcc/testsuite/gcc.target/arm/addr-modes.h b/gcc/testsuite/gcc.target/arm/addr-modes.h
new file mode 100644
index 0000000..eac4678
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/addr-modes.h
@@ -0,0 +1,53 @@
+
+#define PRE_STORE(T) \
+ T * \
+ T ## _pre_store (T *p, T v) \
+ { \
+ *++p = v; \
+ return p; \
+ } \
+
+#define POST_STORE(T) \
+ T * \
+ T ## _post_store (T *p, T v) \
+ { \
+ *p++ = v; \
+ return p; \
+ }
+
+#define POST_STORE_VEC(T, VT, OP) \
+ T * \
+ VT ## _post_store (T * p, VT v) \
+ { \
+ OP (p, v); \
+ p += sizeof (VT) / sizeof (T); \
+ return p; \
+ }
+
+#define PRE_LOAD(T) \
+ void \
+ T ## _pre_load (T *p) \
+ { \
+ extern void f ## T (T*,T); \
+ T x = *++p; \
+ f ## T (p, x); \
+ }
+
+#define POST_LOAD(T) \
+ void \
+ T ## _post_load (T *p) \
+ { \
+ extern void f ## T (T*,T); \
+ T x = *p++; \
+ f ## T (p, x); \
+ }
+
+#define POST_LOAD_VEC(T, VT, OP) \
+ void \
+ VT ## _post_load (T * p) \
+ { \
+ extern void f ## T (T*,T); \
+ VT x = OP (p, v); \
+ p += sizeof (VT) / sizeof (T); \
+ f ## T (p, x); \
+ }
--
2.7.4