OV - exec - Loop 117

	Loop Id: 117	Module: exec	Source: linkCells.c:179-378 [...]	Coverage: 0.07%

0x40a3c4 ORR	W1, WZR, W0

0x40a3c8 ORR	X0, XZR, X19

0x40a3cc BL	40a1e0

0x40a3d0 LDR	X9, [X19, #120]    [11]

0x40a3d4 UBFM	X7, X0, #62, #31

0x40a3d8 LDR	W8, [X19, #12]    [11]

0x40a3dc LDR	W13, [X9, X7]    [1]

0x40a3e0 ADD	W10, W13, W0,LSL #6

0x40a3e4 CMP	W8, W0

0x40a3e8 B.LE	40a3fc

0x40a3ec LDR	W11, [X20]    [4]

0x40a3f0 ADD	W12, W11, #1

0x40a3f4 STR	W12, [X20]    [4]

0x40a3f8 LDR	W13, [X9, X7]    [1]

0x40a3fc ADD	W15, W13, #1

0x40a400 MOVZ	W14, #24

0x40a404 LDR	X18, [X20, #8]    [4]

0x40a408 SBFM	X16, X10, #62, #31

0x40a40c STR	W15, [X9, X7]    [1]

0x40a410 SMADDL	X17, W10, W14, XZR

0x40a414 LDP	X30, X19, [X20, #16]    [4]

0x40a418 STR	W22, [X18, X16]    [8]

0x40a41c LDR	X20, [X20, #32]    [4]

0x40a420 ADD	X22, X19, X17

0x40a424 STR	W21, [X30, X16]    [5]

0x40a428 STR	D15, [X19, X17]    [10]

0x40a42c STP	D14, D13, [X22, #8]    [7]

0x40a430 ADD	X21, X20, X17

0x40a434 STR	D12, [X20, X17]    [3]

0x40a438 STP	D11, D10, [X21, #8]    [6]

0x40a43c LDP	D10, D11, [SP, #48]    [2]

0x40a440 LDP	X19, X20, [SP, #16]    [2]

0x40a444 LDP	X21, X22, [SP, #32]    [2]

0x40a448 LDP	D12, D13, [SP, #64]    [2]

0x40a44c LDP	D14, D15, [SP, #80]    [2]

0x40a450 LDP	X29, X30, [SP], #96    [2]

0x40a454 RET

0x40a458 LDR	D30, [X19, #40]    [9]

0x40a45c SUB	W5, W3, #1

0x40a460 LDR	D31, [X19, #112]    [9]

0x40a464 FSUB	D19, D13, S30

0x40a468 FMUL	D20, D19, D31

0x40a46c FCVTMS	W6, D20

0x40a470 CMP	W3, W6

0x40a474 CSEL	W3, W5, W6, #0

0x40a478 B	40a3c4

/home/hbollore/qaas/qaas-runs/174-108-7908/intel/CoMD/build/CoMD/CoMD/src-openmp/linkCells.c: 179 - 378

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

179:    iOff += boxes->nAtoms[iBox];

180:

181:    // assign values to array elements

182:    if (iBox < boxes->nLocalBoxes)

183:       atoms->nLocal++;

184:    boxes->nAtoms[iBox]++;

185:    atoms->gid[iOff] = gid;

186:    atoms->iSpecies[iOff] = iType;

187:

188:    atoms->r[iOff][0] = x;

189:    atoms->r[iOff][1] = y;

190:    atoms->r[iOff][2] = z;

191:

192:    atoms->p[iOff][0] = px;

193:    atoms->p[iOff][1] = py;

194:    atoms->p[iOff][2] = pz;

195: }

[...]

354:    int iz = (int)(floor((rr[2] - localMin[2])*boxes->invBoxSize[2]));

[...]

373:       if (iz == gridSize[2]) iz = gridSize[2] - 1;

374:    }

375:    else

376:       iz = gridSize[2];

377:

378:    return getBoxFromTuple(boxes, ix, iy, iz);

Coverage (%)	Name	Source Location	Module
►30.77+	unloadAtomsBuffer	haloExchange.c:414	exec
○	haloExchange	haloExchange.c:302	exec
○	timestep	timestep.c:150	exec
○	main	CoMD.c:125	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►20.51+	unloadAtomsBuffer	haloExchange.c:424	exec
○	haloExchange	memUtils.h:28	exec
○	timestep	timestep.c:150	exec
○	main	CoMD.c:125	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►20.51+	unloadAtomsBuffer	haloExchange.c:414	exec
○	haloExchange	memUtils.h:28	exec
○	timestep	timestep.c:150	exec
○	main	CoMD.c:125	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►15.38+	unloadAtomsBuffer	haloExchange.c:424	exec
○	haloExchange	haloExchange.c:302	exec
○	timestep	timestep.c:150	exec
○	main	CoMD.c:125	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►5.13+	createFccLattice	initAtoms.c:96	exec
○	main	CoMD.c:199	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►3.85+	createFccLattice	initAtoms.c:91	exec
○	main	CoMD.c:199	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►2.56+	createFccLattice	initAtoms.c:100	exec
○	main	CoMD.c:199	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	exec
►1.28+	createFccLattice	initAtoms.c:100	exec
○	main	CoMD.c:199	exec
○	__libc_start_call_main		libc.so.6
○	__libc_start_main		libc.so.6
○	_start	CoMD.c:468	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	2.67
CQA speedup if FP arith vectorized	1.33
CQA speedup if fully vectorized	1.50
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.39
Bottlenecks	P12, P13, P14,
Function	putAtomInBox
Source	linkCells.c:179-195,linkCells.c:354-354,linkCells.c:373-378
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	8.00
CQA cycles if no scalar integer	3.00
CQA cycles if FP arith vectorized	6.00
CQA cycles if fully vectorized	5.33
Front-end cycles	5.75
P0 cycles	2.00
P1 cycles	2.00
P2 cycles	2.75
P3 cycles	2.75
P4 cycles	2.67
P5 cycles	2.67
P6 cycles	2.58
P7 cycles	2.58
P8 cycles	2.50
P9 cycles	2.50
P10 cycles	1.00
P11 cycles	1.00
P12 cycles	8.00
P13 cycles	8.00
P14 cycles	8.00
P15 cycles	2.00
P16 cycles	2.00
DIV/SQRT cycles	0.00
Inter-iter dependencies cycles	NA
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	46.00
Nb uops	46.00
Nb loads	NA
Nb stores	8.00
Nb stack references	0.00
FLOP/cycle	0.25
Nb FLOP add-sub	1.00
Nb FLOP mul	1.00
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	29.00
Bytes prefetched	0.00
Bytes loaded	168.00
Bytes stored	64.00
Stride 0	NA
Stride 1	NA
Stride n	NA
Stride unknown	NA
Stride indirect	NA
Vectorization ratio all	17.86
Vectorization ratio load	33.33
Vectorization ratio store	25.00
Vectorization ratio mul	0.00
Vectorization ratio add_sub	0.00
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	NA
Vectorization ratio other	0.00
Vector-efficiency ratio all	45.54
Vector-efficiency ratio load	55.56
Vector-efficiency ratio store	50.00
Vector-efficiency ratio mul	50.00
Vector-efficiency ratio add_sub	30.00
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	NA
Vector-efficiency ratio other	35.00

Metric	Value
CQA speedup if no scalar integer	2.67
CQA speedup if FP arith vectorized	1.33
CQA speedup if fully vectorized	1.50
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.39
Bottlenecks	P12, P13, P14,
Function	putAtomInBox
Source	linkCells.c:179-195,linkCells.c:354-354,linkCells.c:373-378
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	8.00
CQA cycles if no scalar integer	3.00
CQA cycles if FP arith vectorized	6.00
CQA cycles if fully vectorized	5.33
Front-end cycles	5.75
P0 cycles	2.00
P1 cycles	2.00
P2 cycles	2.75
P3 cycles	2.75
P4 cycles	2.67
P5 cycles	2.67
P6 cycles	2.58
P7 cycles	2.58
P8 cycles	2.50
P9 cycles	2.50
P10 cycles	1.00
P11 cycles	1.00
P12 cycles	8.00
P13 cycles	8.00
P14 cycles	8.00
P15 cycles	2.00
P16 cycles	2.00
DIV/SQRT cycles	0.00
Inter-iter dependencies cycles	NA
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	46.00
Nb uops	46.00
Nb loads	NA
Nb stores	8.00
Nb stack references	0.00
FLOP/cycle	0.25
Nb FLOP add-sub	1.00
Nb FLOP mul	1.00
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	29.00
Bytes prefetched	0.00
Bytes loaded	168.00
Bytes stored	64.00
Stride 0	NA
Stride 1	NA
Stride n	NA
Stride unknown	NA
Stride indirect	NA
Vectorization ratio all	17.86
Vectorization ratio load	33.33
Vectorization ratio store	25.00
Vectorization ratio mul	0.00
Vectorization ratio add_sub	0.00
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	NA
Vectorization ratio other	0.00
Vector-efficiency ratio all	45.54
Vector-efficiency ratio load	55.56
Vector-efficiency ratio store	50.00
Vector-efficiency ratio mul	50.00
Vector-efficiency ratio add_sub	30.00
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	NA
Vector-efficiency ratio other	35.00

Path /

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

Function	putAtomInBox
Source file and lines	linkCells.c:179-378
Module	exec

The loop is defined in /home/hbollore/qaas/qaas-runs/174-108-7908/intel/CoMD/build/CoMD/CoMD/src-openmp/linkCells.c:179-195,354,373-378.

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

Ignoring paths for analysis
Failed to get the number of paths
RecMII not computed since number of paths is unknown or > max_paths
Streams not analyzed since number of paths is unknown or > max_paths

gain
potential
hint
expert

Code clean check

Detected a slowdown caused by scalar integer instructions (typically used for address computation). By removing them, you can lower the cost of an iteration from 8.00 to 3.00 cycles (2.67x speedup).

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Vectorization

Your loop is not vectorized. Only 45% of vector register length is used (average across all VPU instructions). By fully vectorizing your loop, you can lower the cost of an iteration from 8.00 to 5.33 cycles (1.50x speedup).

Details

17% of VPU instructions are used in vector version (process two or more data elements in vector registers):

33% of VPU loads are used in vector version.
25% of VPU stores are used in vector version.
0% of VPU addition or subtraction instructions are used in vector version.
0% of VPU multiply instructions are used in vector version.
0% of VPU instructions that are not load, store, addition, subtraction nor multiply instructions are used in vector version.

Since your execution units are vector units, only a fully vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

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 8.00 to 0.50 cycles (16.00x speedup).

FMA

Presence of both ADD/SUB and MUL operations.

Workaround

Try to change order in which elements are evaluated (using parentheses) in arithmetic expressions containing both ADD/SUB and MUL operations to enable your compiler to generate FMA instructions wherever possible. For instance a + b*c is a valid FMA (MUL then ADD). However (a+b)* c cannot be translated into an FMA (ADD then MUL).

Conversion instructions

Detected expensive conversion instructions.

Details

FCVTMS: 1 occurrences►
- /home/hbollore/qaas/qaas-runs/174-108-7908/intel/CoMD/build/CoMD/CoMD/src-openmp/linkCells.c:354

Workaround

Avoid mixing data with different types. In particular, check if the type of constants is the same as array elements.

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

The binary loop is composed of 2 FP arithmetical operations:

1: addition or subtraction
1: multiply

The binary loop is loading 168 bytes. The binary loop is storing 64 bytes.

Arithmetic intensity

Arithmetic intensity is 0.01 FP operations per loaded or stored byte.

General properties

nb instructions	46
loop length	184
nb stack references	0

Front-end

FIT IN UOP CACHE

front end

5.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14	P15	P16
uops	2.00	2.00	2.75	2.75	2.67	2.67	2.58	2.58	2.50	2.50	1.00	1.00	8.00	8.00	8.00	2.00	2.00
cycles	2.00	2.00	2.75	2.75	2.67	2.67	2.58	2.58	2.50	2.50	1.00	1.00	8.00	8.00	8.00	2.00	2.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6: ALU
P7: ALU
P8 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P9 (128 bits): VPU, ALU, FP store data
P10 (128 bits): VPU, ALU, DIV/SQRT
P11 (128 bits): ALU, VPU
P12 (256 bits): store address, load
P13 (256 bits): store address, load
P14 (256 bits): load
P15 (64 bits): store data
P16 (64 bits): store data

Cycles executing div or sqrt instructions

Cycles summary

Front-end	5.75
Overall L1	8.00

Vectorization ratios

INT

all	20%
load	33%
store	25%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
other	0%

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	0%
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

INT+FP

all	17%
load	33%
store	25%
mul	0%
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 8.00 cycles. At this rate:

21% of peak load performance is reached (21.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))
16% of peak store performance is reached (8.00 out of 48.00 bytes stored per cycle (GB/s @ 1GHz))

ASM code

In the binary file, the address of the loop is: 40a458

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14	P15	P16	Latency	Recip. throughput	Vectorization
ORR W1, WZR, W0	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
ORR X0, XZR, X19	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (50.0%)
BL 40a1e0 <getBoxFromTuple>	1	0.50	0.50	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR X9, [X19, #120]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
UBFM X7, X0, #62, #31	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
LDR W8, [X19, #12]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
LDR W13, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W10, W13, W0,LSL #6	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	0	0	2	0.50	scal (25.0%)
CMP W8, W0	1	0	0	0.25	0.25	0	0	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	scal (25.0%)
B.LE 40a3fc <putAtomInBox+0xac>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR W11, [X20]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W12, W11, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
STR W12, [X20]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
LDR W13, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W15, W13, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
MOVZ W14, #24	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
LDR X18, [X20, #8]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
SBFM X16, X10, #62, #31	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR W15, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
SMADDL X17, W10, W14, XZR	1	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	2	1	N/A
LDP X30, X19, [X20, #16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
STR W22, [X18, X16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
LDR X20, [X20, #32]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
ADD X22, X19, X17	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR W21, [X30, X16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
STR D15, [X19, X17]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (50.0%)
STP D14, D13, [X22, #8]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	vect (100.0%)
ADD X21, X20, X17	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR D12, [X20, X17]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (50.0%)
STP D11, D10, [X21, #8]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	vect (100.0%)
LDP D10, D11, [SP, #48]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP X19, X20, [SP, #16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
LDP X21, X22, [SP, #32]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
LDP D12, D13, [SP, #64]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP D14, D15, [SP, #80]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP X29, X30, [SP], #96	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
RET	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR D30, [X19, #40]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (50.0%)
SUB W5, W3, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
LDR D31, [X19, #112]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (50.0%)
FSUB D19, D13, S30	1	0	0	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	2	0.25	scal (50.0%)
FMUL D20, D19, D31	1	0	0	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	3	0.25	scal (50.0%)
FCVTMS W6, D20	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	3	1	scal (50.0%)
CMP W3, W6	1	0	0	0.25	0.25	0	0	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	N/A
CSEL W3, W5, W6, #0	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
B 40a3c4 <putAtomInBox+0x74>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Function	putAtomInBox
Source file and lines	linkCells.c:179-378
Module	exec

Ignoring paths for analysis
Failed to get the number of paths
RecMII not computed since number of paths is unknown or > max_paths
Streams not analyzed since number of paths is unknown or > max_paths

gain
potential
hint
expert

Code clean check

Detected a slowdown caused by scalar integer instructions (typically used for address computation). By removing them, you can lower the cost of an iteration from 8.00 to 3.00 cycles (2.67x speedup).

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Vectorization

Details

17% of VPU instructions are used in vector version (process two or more data elements in vector registers):

33% of VPU loads are used in vector version.
25% of VPU stores are used in vector version.
0% of VPU addition or subtraction instructions are used in vector version.
0% of VPU multiply instructions are used in vector version.
0% of VPU instructions that are not load, store, addition, subtraction nor multiply instructions are used in vector version.

Since your execution units are vector units, only a fully vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

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 8.00 to 0.50 cycles (16.00x speedup).

FMA

Presence of both ADD/SUB and MUL operations.

Workaround

Conversion instructions

Detected expensive conversion instructions.

Details

FCVTMS: 1 occurrences►
- /home/hbollore/qaas/qaas-runs/174-108-7908/intel/CoMD/build/CoMD/CoMD/src-openmp/linkCells.c:354

Workaround

Avoid mixing data with different types. In particular, check if the type of constants is the same as array elements.

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

The binary loop is composed of 2 FP arithmetical operations:

1: addition or subtraction
1: multiply

The binary loop is loading 168 bytes. The binary loop is storing 64 bytes.

Arithmetic intensity

Arithmetic intensity is 0.01 FP operations per loaded or stored byte.

General properties

nb instructions	46
loop length	184
nb stack references	0

Front-end

FIT IN UOP CACHE

front end

5.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14	P15	P16
uops	2.00	2.00	2.75	2.75	2.67	2.67	2.58	2.58	2.50	2.50	1.00	1.00	8.00	8.00	8.00	2.00	2.00
cycles	2.00	2.00	2.75	2.75	2.67	2.67	2.58	2.58	2.50	2.50	1.00	1.00	8.00	8.00	8.00	2.00	2.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6: ALU
P7: ALU
P8 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P9 (128 bits): VPU, ALU, FP store data
P10 (128 bits): VPU, ALU, DIV/SQRT
P11 (128 bits): ALU, VPU
P12 (256 bits): store address, load
P13 (256 bits): store address, load
P14 (256 bits): load
P15 (64 bits): store data
P16 (64 bits): store data

Cycles executing div or sqrt instructions

Cycles summary

Front-end	5.75
Overall L1	8.00

Vectorization ratios

INT

all	20%
load	33%
store	25%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
other	0%

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	0%
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

INT+FP

all	17%
load	33%
store	25%
mul	0%
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 8.00 cycles. At this rate:

21% of peak load performance is reached (21.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))
16% of peak store performance is reached (8.00 out of 48.00 bytes stored per cycle (GB/s @ 1GHz))

ASM code

In the binary file, the address of the loop is: 40a458

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14	P15	P16	Latency	Recip. throughput	Vectorization
ORR W1, WZR, W0	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
ORR X0, XZR, X19	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (50.0%)
BL 40a1e0 <getBoxFromTuple>	1	0.50	0.50	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR X9, [X19, #120]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
UBFM X7, X0, #62, #31	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
LDR W8, [X19, #12]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
LDR W13, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W10, W13, W0,LSL #6	1	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	0	0	2	0.50	scal (25.0%)
CMP W8, W0	1	0	0	0.25	0.25	0	0	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	scal (25.0%)
B.LE 40a3fc <putAtomInBox+0xac>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR W11, [X20]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W12, W11, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
STR W12, [X20]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
LDR W13, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (25.0%)
ADD W15, W13, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
MOVZ W14, #24	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
LDR X18, [X20, #8]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
SBFM X16, X10, #62, #31	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR W15, [X9, X7]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
SMADDL X17, W10, W14, XZR	1	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	2	1	N/A
LDP X30, X19, [X20, #16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
STR W22, [X18, X16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
LDR X20, [X20, #32]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
ADD X22, X19, X17	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR W21, [X30, X16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.50	0.50	0	0.50	0.50	1	0.50	scal (25.0%)
STR D15, [X19, X17]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (50.0%)
STP D14, D13, [X22, #8]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	vect (100.0%)
ADD X21, X20, X17	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
STR D12, [X20, X17]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (50.0%)
STP D11, D10, [X21, #8]	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	vect (100.0%)
LDP D10, D11, [SP, #48]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP X19, X20, [SP, #16]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
LDP X21, X22, [SP, #32]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
LDP D12, D13, [SP, #64]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP D14, D15, [SP, #80]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	vect (100.0%)
LDP X29, X30, [SP], #96	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.50	N/A
RET	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDR D30, [X19, #40]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (50.0%)
SUB W5, W3, #1	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	scal (25.0%)
LDR D31, [X19, #112]	1	0	0	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (50.0%)
FSUB D19, D13, S30	1	0	0	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	2	0.25	scal (50.0%)
FMUL D20, D19, D31	1	0	0	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	3	0.25	scal (50.0%)
FCVTMS W6, D20	1	0	0	0	0	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	3	1	scal (50.0%)
CMP W3, W6	1	0	0	0.25	0.25	0	0	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	N/A
CSEL W3, W5, W6, #0	1	0	0	0.17	0.17	0.17	0.17	0.17	0.17	0	0	0	0	0	0	0	0	0	1	0.17	N/A
B 40a3c4 <putAtomInBox+0x74>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Report Configuration

Code clean check

Workaround

Vectorization

Details

Workaround

Expensive FP math instructions/calls

FMA

Workaround

Conversion instructions

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

Cycles and memory resources usage

ASM code

Code clean check

Workaround

Vectorization

Details

Workaround

Expensive FP math instructions/calls

FMA

Workaround

Conversion instructions

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

Cycles and memory resources usage

ASM code