VS Arduino - nrf51822 + STLink Hardware Debugging

Sep 21^st, 2024 at 5:54am (UTC)

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VS Arduino › Visual Micro › Hardware Debugging (GDB, GDB WiFi, GDB Stub) › nrf51822 + STLink Hardware Debugging - Variable Optimized Out

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nrf51822 + STLink Hardware Debugging - Variable Optimized Out (Read 1433 times)

Simon@Visual Micro Administrator Offline Posts: 2351 Joined: Feb 13^th, 2019	nrf51822 + STLink Hardware Debugging - Variable Optimized Out Dec 15^th, 2020 at 9:42am	Print Post
	About debugging, can I know why variable values are set to "optimzed out" while I have checked "No project + library optimization" (also tried "no optimization") ?


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Simon@Visual Micro Administrator Offline Posts: 2351 Joined: Feb 13^th, 2019	Re: nrf51822 + STLink Hardware Debugging - Variable Optimized Out Reply #1 - Dec 15^th, 2020 at 10:56am	Print Post
	Variables/Functions can be optimized out by the toolchain compiler for a variety of reasons. If the optimization is left as "Default", with the Hardware debugger enabled the system will use -Og (debug optimization), and this should suffice in most cases for debugging. No Optimization (-O0) can also work to avoid this, though may slow the program down, and increase the code size considerably. Can you confirm (with example) what you are seeing that is optimized, which you want to inspect? Also, the Visual Micro Serial Debugger avoids the optimization issue completely, and allows variable tracking, charting, conditional breakpoints, trace points and more via the Serial port.
	« Last Edit: Dec 15^th, 2020 at 10:56am by Simon@Visual Micro »

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entretoize1 Junior Member Offline Posts: 20 Joined: Dec 4^th, 2020	Re: nrf51822 + STLink Hardware Debugging - Variable Optimized Out Reply #2 - Dec 15^th, 2020 at 1:53pm	Print Post
	With "No optimization" I still can see that variable I want to see in this example: Code float x = mpu.getAngleX(); timer = millis(); Serial.println(x); //breakpoint here x value is <optimized out> but should be a float, I tried by adding 1 (x=x+1;) and then I can see it but it's not practical. What is Visual Micro Serial Debugger ? Is it another software ? You help page seems to explain how to do in Visual studio but it's what I'm already doing.


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Simon@Visual Micro Administrator Offline Posts: 2351 Joined: Feb 13^th, 2019	Re: nrf51822 + STLink Hardware Debugging - Variable Optimized Out Reply #3 - Dec 15^th, 2020 at 2:09pm	Print Post
	Have you tried watching "mpu.getAngleX()" instead of "x"? (In this case I expect the compiler can see it is assigned, just to be used with no other operations, so reduces this to essentially "Serial.println(mpu.getAngleX())") The Visual Micro Serial debugger is the "Serial" option on the Debug Listing (set to Hardware to use STLink), and works slightly differently to the hardware debugger as no additional hardware is needed. It is built into the Visual Micro Extension, so looks very similar from the UI as both are in VS. The differences between these two debugging methods are listed below, with a vide example of the Serial Debug Charting in action. Doc: Differences between Visual Micro Debugging, Gdb Debugging and Visual Studio's Debugging of Native Platforms Video Example: Serial Debugger Charting with vMicro


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entretoize1 Junior Member Offline Posts: 20 Joined: Dec 4^th, 2020	Re: nrf51822 + STLink Hardware Debugging - Variable Optimized Out Reply #4 - Dec 15^th, 2020 at 3:01pm	Print Post
	Watching mpu.getAngleX() doesn't work (can't be evaluated). Anyway , I can (and will) do x=x+0 and then x is visible... From what I understand, I can't use the serial option (tried and breakpoints doesn't work) as I'm using a STlink, right ?


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Simon@Visual Micro Administrator Offline Posts: 2351 Joined: Feb 13^th, 2019	Re: nrf51822 + STLink Hardware Debugging - Variable Optimized Out Reply #5 - Dec 15^th, 2020 at 5:14pm	Print Post
	Understood, there may be alternative options to step into the getAngleX() method to review this at runtime. The Serial Debugger is a complete replacement for the Hardware Debugging, so the options cannot be selected together. It also requires the Serial output to work for the board in the Serial Monitor (which I believe is an issue for your configuration from the other thread), as this is what the debugger uses to send the messages to/from the board/pc.


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