Add some more consts to get data moved from .data to .rodata

[akosthekiss]

We already had some consts but it was still not enough.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

[akosthekiss]

Interestingly, the effect is visible in debug builds only: large chunks (2-4K) of data get moved from .data to .rodata. Details below.

filename	master/text	master/data	pr906/text	pr906/data	gain/text	gain/data
release.armv7lhf_linux/jerry	197295	1096	197298	1096	-3	0
release.armv7lhf_linux-cp/jerry	143284	812	143284	812	0	0
release.armv7lhf_linux-cp_minimal/jerry	88091	192	88091	192	0	0
release.armv7lhf_linux-mem_stats/jerry	197855	1096	197858	1096	-3	0
release.armv7lhf_linux-mem_stress_test/jerry	197231	1096	197234	1096	-3	0
release.mcu_stm32f3-cp.bin/jerry	144356	260	144356	260	0	0
release.mcu_stm32f3-cp_minimal.bin/jerry	82704	68	82704	68	0	0
release.mcu_stm32f4-cp.bin/jerry	144356	260	144356	260	0	0
release.mcu_stm32f4-cp_minimal.bin/jerry	82704	68	82704	68	0	0
release.x64_linux/jerry	279890	1373	279890	1373	0	0
release.x64_linux-cp/jerry	211932	989	211932	989	0	0
release.x64_linux-cp_minimal/jerry	133068	204	133068	204	0	0
release.x64_linux-mem_stats/jerry	280923	1373	280923	1373	0	0
release.x64_linux-mem_stress_test/jerry	279917	1373	279917	1373	0	0
debug.armv7lhf_linux/jerry	732048	3272	734224	1104	-2176	2168
debug.armv7lhf_linux-cp/jerry	536720	2988	538904	820	-2184	2168
debug.armv7lhf_linux-cp_minimal/jerry	366772	2384	368952	216	-2180	2168
debug.armv7lhf_linux-mem_stats/jerry	735596	3272	737772	1104	-2176	2168
debug.armv7lhf_linux-mem_stress_test/jerry	732096	3272	734272	1104	-2176	2168
debug.mcu_stm32f4-cp.bin/jerry	547060	2484	549244	316	-2184	2168
debug.mcu_stm32f4-cp_minimal.bin/jerry	365828	2272	368008	104	-2180	2168
debug.x64_linux/jerry	808414	5780	812894	1348	-4480	4432
debug.x64_linux-cp/jerry	628393	5492	632937	1060	-4544	4432
debug.x64_linux-cp_minimal/jerry	438533	4688	442981	272	-4448	4416
debug.x64_linux-mem_stats/jerry	813019	5780	817499	1348	-4480	4432
debug.x64_linux-mem_stress_test/jerry	808434	5780	812914	1348	-4480	4432

[akosthekiss]

If applied together with #905, it does not matter anymore whether debug or release configuration is built, r/w data is always less than 100 bytes. Details below.

filename	master/text	master/data	pr905+906/text	pr905+906/data	gain/text	gain/data
release.armv7lhf_linux/jerry	197295	1096	195940	52	1355	1044
release.armv7lhf_linux-cp/jerry	143284	812	142140	52	1144	760
release.armv7lhf_linux-cp_minimal/jerry	88091	192	87953	0	138	192
release.armv7lhf_linux-mem_stats/jerry	197855	1096	196536	52	1319	1044
release.armv7lhf_linux-mem_stress_test/jerry	197231	1096	195572	52	1659	1044
release.mcu_stm32f3-cp.bin/jerry	144356	260	142748	72	1608	188
release.mcu_stm32f3-cp_minimal.bin/jerry	82704	68	82436	20	268	48
release.mcu_stm32f4-cp.bin/jerry	144356	260	142748	72	1608	188
release.mcu_stm32f4-cp_minimal.bin/jerry	82704	68	82436	20	268	48
release.x64_linux/jerry	279890	1373	278590	61	1300	1312
release.x64_linux-cp/jerry	211932	989	210702	61	1230	928
release.x64_linux-cp_minimal/jerry	133068	204	132993	0	75	204
release.x64_linux-mem_stats/jerry	280923	1373	280071	61	852	1312
release.x64_linux-mem_stress_test/jerry	279917	1373	279031	61	886	1312
debug.armv7lhf_linux/jerry	732048	3272	734008	60	-1960	3212
debug.armv7lhf_linux-cp/jerry	536720	2988	537776	60	-1056	2928
debug.armv7lhf_linux-cp_minimal/jerry	366772	2384	368268	24	-1496	2360
debug.armv7lhf_linux-mem_stats/jerry	735596	3272	737508	60	-1912	3212
debug.armv7lhf_linux-mem_stress_test/jerry	732096	3272	734056	60	-1960	3212
debug.mcu_stm32f4-cp.bin/jerry	547060	2484	547212	76	-152	2408
debug.mcu_stm32f4-cp_minimal.bin/jerry	365828	2272	367392	44	-1564	2228
debug.x64_linux/jerry	808414	5780	817371	68	-8957	5712
debug.x64_linux-cp/jerry	628393	5492	635223	68	-6830	5424
debug.x64_linux-cp_minimal/jerry	438533	4688	443438	32	-4905	4656
debug.x64_linux-mem_stats/jerry	813019	5780	821176	68	-8157	5712
debug.x64_linux-mem_stress_test/jerry	808434	5780	817391	68	-8957	5712

[akosthekiss]

Note to the PR, might help others as it helped me:

• const T * is a read-write pointer to read-only data
• T * const is a read-only pointer to read-write data
• const T * const is a read-only pointer to read-only data

[LaszloLango]

LGTM

[zherczeg]

I thought quoted string constants are always .rodata. At least compiler complains if you pass them as char* in when certain compiler flags are enabled.

[akosthekiss]

@zherczeg Does that mean that we should avoid these changes?

[zherczeg]

I am not sure which part provides the gain here. But it looks like a gain, so I have no objection.

[akosthekiss]

I've taken an objdump of jerry, and that has revealed that those globals which have been touched in this PR were all in .data, not in .rodata.