OV - exec - Loop 153

	Loop Id: 153	Module: exec	Source: advec_cell.cpp:147-150 [...]	Coverage: 1.09%

0x428920 SEL	Z23.D, P1, Z4.D, Z17.D

0x428924 ADD	X10, X10, X8

0x428928 SDIVR	Z23.D, P0/M, Z23.D, Z22.D

0x42892c ADD	Z24.D, Z5.D, Z23.D

0x428930 MOVPRFX	Z25, Z22

0x428934 MLS	Z25.D, P0/M, Z23.D, Z4.D

0x428938 ADD	Z23.D, Z7.D, Z23.D

0x42893c ADD	Z22.D, Z22.D, Z16.D

0x428940 SXTW	Z24.D, P0/M, Z24.D

0x428944 SXTW	Z23.D, P0/M, Z23.D

0x428948 MOVPRFX	Z26, Z0

0x42894c MUL	Z26.D, P0/M, Z26.D, Z24.D

0x428950 MUL	Z23.D, P0/M, Z23.D, Z1.D

0x428954 MOVPRFX	Z28, Z1

0x428958 MUL	Z28.D, P0/M, Z28.D, Z24.D

0x42895c ADD	Z25.D, Z6.D, Z25.D

0x428960 ADR	Z27.D, [Z18, Z25.D,SXTW #3]    [11]

0x428964 ADR	Z26.D, [Z27, Z26.D,LSL #3]    [10]

0x428968 ADR	Z27.D, [Z19, Z25.D,SXTW #3]    [13]

0x42896c ADR	Z23.D, [Z27, Z23.D,LSL #3]    [9]

0x428970 ADR	Z27.D, [Z27, Z28.D,LSL #3]    [9]

0x428974 LD1D	{Z28.D}, P1/Z, [V26.D]    [6]

0x428978 LD1D	{Z23.D}, P1/Z, [V23.D]    [3]

0x42897c LD1D	{Z27.D}, P1/Z, [V27.D]    [8]

0x428980 FADD	Z23.D, Z23.D, Z28.D

0x428984 ADR	Z28.D, [Z20, Z25.D,SXTW #3]    [1]

0x428988 ADR	Z25.D, [Z21, Z25.D,SXTW #3]    [2]

0x42898c FSUB	Z23.D, Z23.D, Z27.D

0x428990 MOVPRFX	Z27, Z2

0x428994 MUL	Z27.D, P0/M, Z27.D, Z24.D

0x428998 MUL	Z24.D, P0/M, Z24.D, Z3.D

0x42899c ADR	Z27.D, [Z28, Z27.D,LSL #3]    [12]

0x4289a0 ADR	Z24.D, [Z25, Z24.D,LSL #3]    [5]

0x4289a4 ST1D	{Z23.D}, P1, [V27.D]    [7]

0x4289a8 LD1D	{Z23.D}, P1/Z, [V26.D]    [6]

0x4289ac ST1D	{Z23.D}, P1, [V24.D]    [4]

0x4289b0 WHILELO	P1.D, X10, X9

0x4289b4 B.MI	428920

/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/advec_cell.cpp: 147 - 150

--------------------------------------------------------------------------------

147:       for (int j = (y_min - 2 + 1); j < (y_max + 2 + 2); j++) {

148:         for (int i = (x_min - 2 + 1); i < (x_max + 2 + 2); i++) {

149:           pre_vol(i, j) = volume(i, j) + vol_flux_y(i + 0, j + 1) - vol_flux_y(i, j);

150:           post_vol(i, j) = volume(i, j);

/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/context.h: 69 - 69

--------------------------------------------------------------------------------

69:   T &operator()(size_t i, size_t j) const { return data[i + j * sizeX]; }

Coverage (%)	Name	Source Location	Module
►98.42+	__kmp_invoke_microtask		libomp.so
○	__kmp_invoke_task_func		libomp.so
○	__kmp_launch_thread		libomp.so
○	__kmp_launch_worker(void*)		libomp.so
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.58+	__kmp_invoke_microtask		libomp.so
○	__kmp_invoke_task_func		libomp.so
○	__kmp_fork_call		libomp.so
○	__kmpc_fork_call		libomp.so
○	advec_cell_kernel(int, int, in[...]	advec_cell.cpp:146	exec
○	advec_cell_driver(global_varia[...]	advec_cell.cpp:232	exec
○	advection(global_variables&)	advection.cpp:81	exec
○	hydro(global_variables&, paral[...]	basic_string.h:1077	exec
○	main	clover_leaf.cpp:209	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	ostream:93	exec

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

Path /

Metric	Value
CQA speedup if no scalar integer	1.00
CQA speedup if FP arith vectorized	1.00
CQA speedup if fully vectorized	1.30 - 1.00
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	3.05 - 1.38
Bottlenecks	P6, P8,
Function	advec_cell_kernel(int, int, int, int, int, int, clover::Buffer1D&, clover::Buffer1D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&) [clone .omp_outlined.9]
Source	advec_cell.cpp:147-150,context.h:69-69
Source loop unroll info	not unrolled or unrolled with no peel/tail loop
Source loop unroll confidence level	max
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	14.50 - 20.00
CQA cycles if no scalar integer	14.50 - 20.00
CQA cycles if FP arith vectorized	14.50 - 20.00
CQA cycles if fully vectorized	11.13 - 20.00
Front-end cycles	4.75
P0 cycles	0.50
P1 cycles	0.50
P2 cycles	0.50
P3 cycles	0.25
P4 cycles	1.00
P5 cycles	0.25
P6 cycles	14.50
P7 cycles	14.50
P8 cycles	3.00
P9 cycles	3.00
P10 cycles	2.00
P11 cycles	2.00
P12 cycles	2.00
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	0.87 - 20.00
Inter-iter dependencies cycles	2
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	38.00
Nb uops	38.00
Nb loads	NA
Nb stores	2.00
Nb stack references	0.00
FLOP/cycle	0.55 - 0.40
Nb FLOP add-sub	8.00
Nb FLOP mul	0.00
Nb FLOP fma	0.00
Nb FLOP div	0.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	9.66 - 13.32
Bytes prefetched	0.00
Bytes loaded	129.13
Bytes stored	64.00
Stride 0	0.00
Stride 1	0.00
Stride n	0.00
Stride unknown	9.00
Stride indirect	4.00
Vectorization ratio all	62.86
Vectorization ratio load	30.77
Vectorization ratio store	100.00
Vectorization ratio mul	100.00
Vectorization ratio add_sub	43.75
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	100.00
Vectorization ratio other	42.86
Vector-efficiency ratio all	80.71
Vector-efficiency ratio load	48.08
Vector-efficiency ratio store	100.00
Vector-efficiency ratio mul	100.00
Vector-efficiency ratio add_sub	57.81
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	100.00
Vector-efficiency ratio other	100.00

Metric	Value
CQA speedup if no scalar integer	1.00
CQA speedup if FP arith vectorized	1.00
CQA speedup if fully vectorized	1.30 - 1.00
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	3.05 - 1.38
Bottlenecks	P6, P8,
Function	advec_cell_kernel(int, int, int, int, int, int, clover::Buffer1D&, clover::Buffer1D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&) [clone .omp_outlined.9]
Source	advec_cell.cpp:147-150,context.h:69-69
Source loop unroll info	not unrolled or unrolled with no peel/tail loop
Source loop unroll confidence level	max
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	14.50 - 20.00
CQA cycles if no scalar integer	14.50 - 20.00
CQA cycles if FP arith vectorized	14.50 - 20.00
CQA cycles if fully vectorized	11.13 - 20.00
Front-end cycles	4.75
P0 cycles	0.50
P1 cycles	0.50
P2 cycles	0.50
P3 cycles	0.25
P4 cycles	1.00
P5 cycles	0.25
P6 cycles	14.50
P7 cycles	14.50
P8 cycles	3.00
P9 cycles	3.00
P10 cycles	2.00
P11 cycles	2.00
P12 cycles	2.00
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	0.87 - 20.00
Inter-iter dependencies cycles	2
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	38.00
Nb uops	38.00
Nb loads	NA
Nb stores	2.00
Nb stack references	0.00
FLOP/cycle	0.55 - 0.40
Nb FLOP add-sub	8.00
Nb FLOP mul	0.00
Nb FLOP fma	0.00
Nb FLOP div	0.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	9.66 - 13.32
Bytes prefetched	0.00
Bytes loaded	129.13
Bytes stored	64.00
Stride 0	0.00
Stride 1	0.00
Stride n	0.00
Stride unknown	9.00
Stride indirect	4.00
Vectorization ratio all	62.86
Vectorization ratio load	30.77
Vectorization ratio store	100.00
Vectorization ratio mul	100.00
Vectorization ratio add_sub	43.75
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	100.00
Vectorization ratio other	42.86
Vector-efficiency ratio all	80.71
Vector-efficiency ratio load	48.08
Vector-efficiency ratio store	100.00
Vector-efficiency ratio mul	100.00
Vector-efficiency ratio add_sub	57.81
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	100.00
Vector-efficiency ratio other	100.00

Path /

Average path: Display a virtual path defined by average values of all real paths

Function	advec_cell_kernel(int, int, int, int, int, int, clover::Buffer1D&, clover::Buffer1D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&) [clone .omp_outlined.9]
Source file and lines	advec_cell.cpp:147-150
Module	exec

The loop is defined in:

/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/advec_cell.cpp:147-150
/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/context.h:69

The related source loop is not unrolled or unrolled with no peel/tail loop.

gain
potential
hint
expert

Vectorization

Your loop is partially vectorized. 80% of vector register length is used (average across all VPU instructions).

Details

62% of VPU instructions are used in vector version (process two or more data elements in vector registers):

30% of VPU loads are used in vector version.
43% of VPU addition or subtraction instructions are used in vector version.
42% of VPU instructions that are not load, store, addition, subtraction nor multiply instructions are used in vector version.

Expensive FP math instructions/calls

Detected performance impact from expensive FP math instructions/calls. By removing/reexpressing them, you can lower the cost of an iteration from 20.00 to 14.00 cycles (1.43x speedup).

Slow data structures access

Detected data structures (typically arrays) that cannot be efficiently read/written

Details

Constant unknown stride: 9 occurrence(s)
Irregular (variable stride) or indirect: 4 occurrence(s)

Non-unit stride (uncontiguous) accesses are not efficiently using data caches

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)
Try to remove indirect accesses. If applicable, precompute elements out of the innermost loop.

Matching between your loop (in the source code) and the binary loop

The binary loop is composed of 8 FP arithmetical operations:

8: addition or subtraction

The binary loop is loading 129 bytes. The binary loop is storing 64 bytes.

Arithmetic intensity

Arithmetic intensity is 0.04 FP operations per loaded or stored byte.

General properties

nb instructions	38
nb uops	38
loop length	152
used w registers	0
used x registers	3
used b registers	0
used h registers	0
used s registers	0
used d registers	0
used q registers	0
used v registers	4
used z registers	21
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	4.75 cycles
front end	4.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	0.50	0.50	0.50	0.25	1.00	0.25	14.50	14.50	3.00	3.00	2.00	2.00	2.00	0.00	0.00
cycles	0.50	0.50	0.50	0.25	1.00	0.25	14.50	14.50	3.00	3.00	2.00	2.00	2.00	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	0.87-20.00
Longest recurrence chain latency (RecMII)	2.00

Cycles summary

Front-end	4.75
Dispatch	14.50
DIV/SQRT	0.87-20.00
Data deps.	2.00
Overall L1	14.50-20.00

Vectorization ratios

INT

all	60%
load	30%
store	100%
mul	100%
add-sub	35%
fma	NA (no fma vectorizable/vectorized instructions)
other	50%

all	100%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	100%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	62%
load	30%
store	100%
mul	100%
add-sub	43%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	100%
other	42%

Vector efficiency ratios

INT

all	79%
load	48%
store	100%
mul	100%
add-sub	51%
fma	NA (no fma vectorizable/vectorized instructions)
other	100%

all	100%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	100%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	80%
load	48%
store	100%
mul	100%
add-sub	57%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	100%
other	100%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 20.00 cycles. At this rate:

6% of peak load performance is reached (6.46 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))
6% of peak store performance is reached (3.20 out of 48.00 bytes stored per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the loop is: 428920

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	Latency	Recip. throughput	Vectorization
SEL Z23.D, P1, Z4.D, Z17.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADD X10, X10, X8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
SDIVR Z23.D, P0/M, Z23.D, Z22.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	7-20	0.87-20	vect (100.0%)
ADD Z24.D, Z5.D, Z23.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
MOVPRFX Z25, Z22	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MLS Z25.D, P0/M, Z23.D, Z4.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADD Z23.D, Z7.D, Z23.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADD Z22.D, Z22.D, Z16.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
SXTW Z24.D, P0/M, Z24.D	1	0	0	0	0	0	0	0	1	0	0	0	0	0	2	1	vect (100.0%)
SXTW Z23.D, P0/M, Z23.D	1	0	0	0	0	0	0	0	1	0	0	0	0	0	2	1	vect (100.0%)
MOVPRFX Z26, Z0	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z26.D, P0/M, Z26.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MUL Z23.D, P0/M, Z23.D, Z1.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MOVPRFX Z28, Z1	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z28.D, P0/M, Z28.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADD Z25.D, Z6.D, Z25.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADR Z27.D, [Z18, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z26.D, [Z27, Z26.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z27.D, [Z19, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z23.D, [Z27, Z23.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z27.D, [Z27, Z28.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
LD1D {Z28.D}, P1/Z, [V26.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
LD1D {Z23.D}, P1/Z, [V23.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
LD1D {Z27.D}, P1/Z, [V27.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
FADD Z23.D, Z23.D, Z28.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADR Z28.D, [Z20, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z25.D, [Z21, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
FSUB Z23.D, Z23.D, Z27.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
MOVPRFX Z27, Z2	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z27.D, P0/M, Z27.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MUL Z24.D, P0/M, Z24.D, Z3.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADR Z27.D, [Z28, Z27.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z24.D, [Z25, Z24.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ST1D {Z23.D}, P1, [V27.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.50	0.50	0	6	2	vect (100.0%)
LD1D {Z23.D}, P1/Z, [V26.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
ST1D {Z23.D}, P1, [V24.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.50	0.50	0	6	2	vect (100.0%)
WHILELO P1.D, X10, X9	1	0	0	0	0	1	0	0	0	0	0	0	0	0	3	2	N/A
B.MI 428920 <_Z17advec_cell_kerneliiiiiiRN6clover8Buffer1DIdEES2_RNS_8Buffer2DIdEES5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_.omp_outlined.9+0x130>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Function	advec_cell_kernel(int, int, int, int, int, int, clover::Buffer1D&, clover::Buffer1D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&, clover::Buffer2D&) [clone .omp_outlined.9]
Source file and lines	advec_cell.cpp:147-150
Module	exec

The loop is defined in:

/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/advec_cell.cpp:147-150
/home/eoseret/qaas/qaas_runs/178-219-7589/intel/CloverLeaf2.0-CXX/build/CloverLeaf2.0-CXX/src/omp/context.h:69

The related source loop is not unrolled or unrolled with no peel/tail loop.

gain
potential
hint
expert

Vectorization

Your loop is partially vectorized. 80% of vector register length is used (average across all VPU instructions).

Details

62% of VPU instructions are used in vector version (process two or more data elements in vector registers):

30% of VPU loads are used in vector version.
43% of VPU addition or subtraction instructions are used in vector version.
42% of VPU instructions that are not load, store, addition, subtraction nor multiply instructions are used in vector version.

Expensive FP math instructions/calls

Detected performance impact from expensive FP math instructions/calls. By removing/reexpressing them, you can lower the cost of an iteration from 20.00 to 14.00 cycles (1.43x speedup).

Slow data structures access

Detected data structures (typically arrays) that cannot be efficiently read/written

Details

Constant unknown stride: 9 occurrence(s)
Irregular (variable stride) or indirect: 4 occurrence(s)

Non-unit stride (uncontiguous) accesses are not efficiently using data caches

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)
Try to remove indirect accesses. If applicable, precompute elements out of the innermost loop.

Matching between your loop (in the source code) and the binary loop

The binary loop is composed of 8 FP arithmetical operations:

8: addition or subtraction

The binary loop is loading 129 bytes. The binary loop is storing 64 bytes.

Arithmetic intensity

Arithmetic intensity is 0.04 FP operations per loaded or stored byte.

General properties

nb instructions	38
nb uops	38
loop length	152
used w registers	0
used x registers	3
used b registers	0
used h registers	0
used s registers	0
used d registers	0
used q registers	0
used v registers	4
used z registers	21
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	4.75 cycles
front end	4.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	0.50	0.50	0.50	0.25	1.00	0.25	14.50	14.50	3.00	3.00	2.00	2.00	2.00	0.00	0.00
cycles	0.50	0.50	0.50	0.25	1.00	0.25	14.50	14.50	3.00	3.00	2.00	2.00	2.00	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	0.87-20.00
Longest recurrence chain latency (RecMII)	2.00

Cycles summary

Front-end	4.75
Dispatch	14.50
DIV/SQRT	0.87-20.00
Data deps.	2.00
Overall L1	14.50-20.00

Vectorization ratios

INT

all	60%
load	30%
store	100%
mul	100%
add-sub	35%
fma	NA (no fma vectorizable/vectorized instructions)
other	50%

all	100%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	100%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	62%
load	30%
store	100%
mul	100%
add-sub	43%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	100%
other	42%

Vector efficiency ratios

INT

all	79%
load	48%
store	100%
mul	100%
add-sub	51%
fma	NA (no fma vectorizable/vectorized instructions)
other	100%

all	100%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	100%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	80%
load	48%
store	100%
mul	100%
add-sub	57%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	100%
other	100%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 20.00 cycles. At this rate:

6% of peak load performance is reached (6.46 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))
6% of peak store performance is reached (3.20 out of 48.00 bytes stored per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the loop is: 428920

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	Latency	Recip. throughput	Vectorization
SEL Z23.D, P1, Z4.D, Z17.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADD X10, X10, X8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
SDIVR Z23.D, P0/M, Z23.D, Z22.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	7-20	0.87-20	vect (100.0%)
ADD Z24.D, Z5.D, Z23.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
MOVPRFX Z25, Z22	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MLS Z25.D, P0/M, Z23.D, Z4.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADD Z23.D, Z7.D, Z23.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADD Z22.D, Z22.D, Z16.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
SXTW Z24.D, P0/M, Z24.D	1	0	0	0	0	0	0	0	1	0	0	0	0	0	2	1	vect (100.0%)
SXTW Z23.D, P0/M, Z23.D	1	0	0	0	0	0	0	0	1	0	0	0	0	0	2	1	vect (100.0%)
MOVPRFX Z26, Z0	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z26.D, P0/M, Z26.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MUL Z23.D, P0/M, Z23.D, Z1.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MOVPRFX Z28, Z1	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z28.D, P0/M, Z28.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADD Z25.D, Z6.D, Z25.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADR Z27.D, [Z18, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z26.D, [Z27, Z26.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z27.D, [Z19, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z23.D, [Z27, Z23.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z27.D, [Z27, Z28.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
LD1D {Z28.D}, P1/Z, [V26.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
LD1D {Z23.D}, P1/Z, [V23.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
LD1D {Z27.D}, P1/Z, [V27.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
FADD Z23.D, Z23.D, Z28.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
ADR Z28.D, [Z20, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z25.D, [Z21, Z25.D,SXTW #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
FSUB Z23.D, Z23.D, Z27.D	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	vect (100.0%)
MOVPRFX Z27, Z2	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (100.0%)
MUL Z27.D, P0/M, Z27.D, Z24.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
MUL Z24.D, P0/M, Z24.D, Z3.D	1	0	0	0	0	0	0	1	0	0	0	0	0	0	5	2	vect (100.0%)
ADR Z27.D, [Z28, Z27.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ADR Z24.D, [Z25, Z24.D,LSL #3]	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	2	0.50	scal (25.0%)
ST1D {Z23.D}, P1, [V27.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.50	0.50	0	6	2	vect (100.0%)
LD1D {Z23.D}, P1/Z, [V26.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.33	0.33	0.33	9	2	vect (100.0%)
ST1D {Z23.D}, P1, [V24.D]	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0.50	0.50	0	6	2	vect (100.0%)
WHILELO P1.D, X10, X9	1	0	0	0	0	1	0	0	0	0	0	0	0	0	3	2	N/A
B.MI 428920 <_Z17advec_cell_kerneliiiiiiRN6clover8Buffer1DIdEES2_RNS_8Buffer2DIdEES5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_S5_.omp_outlined.9+0x130>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Report Configuration

Vectorization

Details

Expensive FP math instructions/calls

Slow data structures access

Details

Workaround

Matching between your loop (in the source code) and the binary loop

Arithmetic intensity

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code

Vectorization

Details

Expensive FP math instructions/calls

Slow data structures access

Details

Workaround

Matching between your loop (in the source code) and the binary loop

Arithmetic intensity

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code