Show page

Differences

This shows you the differences between two versions of the page.

--- iothings:proiecte:2022sric:ub-benchmark [2023/06/01 21:58]
lucian_ioan.popescu [Results]
+++ iothings:proiecte:2022sric:ub-benchmark [2023/06/01 22:09] (current)
lucian_ioan.popescu [Running the Benchmarks]
@@ Line 64: / Line 64: @@
 Next I will present all configurations used for this experiment. I used a total of 13 configurations based on various flags that change the behavior of the compiler with regards to exploiting UB.
-^ UB flag      ^ Description       ^
+^ No ^ UB flag      ^ Description       ^
-| -fwrapv    | Treat signed overflow as two's complement    |
+| 1 | -fwrapv    | Treat signed overflow as two's complement    |
-| -fno-strict-aliasing    | Don't use type based alias analysis    |
+| 2 | -fno-strict-aliasing    | Don't use type based alias analysis    |
-| -fstrict-enums    | Enable optimizations that take advantage of enum's value range     |
+| 3 | -fstrict-enums    | Enable optimizations that take advantage of enum's value range     |
-| -fno-delete-null-pointer-checks    | Assume that programs can safely dereference null pointers     |
+| 4 | -fno-delete-null-pointer-checks    | Assume that programs can safely dereference null pointers     |
-| -fno-finite-loops    | Don't assume that all loops are finite     |
+| 5 | -fno-finite-loops    | Don't assume that all loops are finite     |
-| -fconstrain-shift-value    | Constrain shift RHS so it doesn't produce undefined results when RHS >= bitwitdh     |
+| 6 | -fconstrain-shift-value    | Constrain shift RHS so it doesn't produce undefined results when RHS >= bitwitdh     |
-| -fno-constrain-bool-value    | Don't constrain bool values in {0,1}     |
+| 7 | -fno-constrain-bool-value    | Don't constrain bool values in {0,1}     |
-| all + -O2    | All flags from above + -O2     |
+| 8 | all + -O2    | All flags from above + -O2     |
-| all + -Os    | All flags from above + -Os     |
+| 9 | all + -Os    | All flags from above + -Os     |
-| base + -O2    | No flag from above + -O2    |
+| 10 | base + -O2    | No flag from above + -O2    |
-| base + -Os    | No flag from above + -Os     |
+| 11 | base + -Os    | No flag from above + -Os     |
-| -fno-use-default-alignment    | Use alignment of one for all memory operations     |
+| 12 | -fno-use-default-alignment    | Use alignment of one for all memory operations     |
 ==== Results ====
@@ Line 100: / Line 100: @@
 ==== Conclusions and Further Work ====
-The results show that there is not much difference in terms of code size or code speed in the context of undefined behavior for Nuttx and Coremark. One reason for that might be that while developing those systems, the developers made little to no use of undefined behavior. Another reason might be that Xtensa LLVM cannot take proper advantage of undefined behavior when triggering optimizations for Nuttx and Coremark.
+The results show that there is not much difference in terms of code size, code speed and power consumption in the context of undefined behavior for Nuttx and Coremark. One reason for that might be that while developing those systems, the developers made little to no use of undefined behavior. Another reason might be that Xtensa LLVM cannot take proper advantage of undefined behavior when triggering optimizations for Nuttx and Coremark.
 Those are interesting paths worth further researching. Moreover, rerunning the experiments with a better USB tester can lead to more accurate results with regards to the power consumption capabilities of the Xtensa processsor.
@@ Line 106: / Line 106: @@
 ==== References ====
-[1] [[https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7|A bit of background on compilers exploiting signed overflow]]
+[1] [[https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7|A bit of background on compilers exploiting signed overflow]] \\
+[2] [[https://meka.rs/blog/2017/07/03/nuttx-and-clang/|NuttX and Clang]] \\
-[2] [[https://meka.rs/blog/2017/07/03/nuttx-and-clang/|NuttX and Clang]]
+[3] [[https://github.com/espressif/llvm-project|Fork of LLVM targeted at Xtensa]] \\
+[4] [[https://www.cadence.com/content/dam/cadence-www/global/en_US/documents/tools/ip/tensilica-ip/isa-summary.pdf|Xtensa ISA]] \\
-[3] [[https://github.com/espressif/llvm-project|Fork of LLVM targeted at Xtensa]]
+[5] [[https://github.com/lucic71/nuttx|My fork of Nuttx]] \\
+[6] [[https://github.com/lucic71/llvm-project-espressif|My fork of Xtensa LLVM]] \\
-[4] [[https://www.cadence.com/content/dam/cadence-www/global/en_US/documents/tools/ip/tensilica-ip/isa-summary.pdf|Xtensa ISA]]
+[7] [[https://www.eembc.org/coremark/|Coremark]] \\
+[8] [[https://www.emag.ro/tester-usb-ut658-uni-t-afisaj-lcd-9999-mah-mie0415/pd/DYL0T7MBM/?ref=hdr-favorite_products|Tester USB UT658 Uni-T, afisaj LCD, 9999 mAh]] \\
-[5] [[https://github.com/lucic71/nuttx|My fork of Nuttx]]
+[9] [[https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf|ESP32 datasheet]] \\
-[6] [[https://github.com/lucic71/llvm-project-espressif|My fork of Xtensa LLVM]]
-[7] [[https://www.eembc.org/coremark/|Coremark]]
-[8] [[https://www.emag.ro/tester-usb-ut658-uni-t-afisaj-lcd-9999-mah-mie0415/pd/DYL0T7MBM/?ref=hdr-favorite_products|Tester USB UT658 Uni-T, afisaj LCD, 9999 mAh]]
-[9] [[https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf|ESP32 datasheet]]
 [10] [[https://www.emag.ro/placa-dezvoltare-esp32-devkit-v1-ai669/pd/DXV9FDMBM/|Placa dezvoltare ESP32, DEVKIT V1]]