Pelles C > General discussions
Pelles V11 Warnings
John Z:
Well I finally jumped into Pelles Version 11. However like the old lady with the shoe who had so many children she did not know what to do, I've got so many new warnings it is overwhelming as I try to resolve each.
So here is the first warning which I find a bit weird.
warning #2242: Call to 'memset' removed.
I've got many of these. Here is the case
--- Code: ---wchar_t HR[10]; // 10 wide characters
memset(HR,0,10); // fill 1st 10 bytes with 0 <- warning #2242: Call to 'memset' removed.
--- End code ---
So ok you might question why I do it - but why is it wrong?
Then there is this to add, and confound, When this is the code:
--- Code: ---wchar_t HR[10]; // 10 wide characters
memset(HR,0,10); // fill 1st 10 bytes with 0
memset(HR,0,10); // fill 1st 10 bytes with 0
--- End code ---
There are NO warnings about removing memset .....
I'm attaching the simple as possible project as a zip. It includes both cases above as well as
alternative &HR[0] trial. Don't need to run anything just compile it.
Then - is the compiler really removing the memset commands?
Better to understand than to just disable the warning IMO...
Thanks for any clarification,
John Z
TimoVJL:
optimization can replace memset with inline code.
frankie:
In V11 Pelle spent a lot of time and efforts to enhance the optimizations.
--- Quote from: John Z on April 24, 2022, 06:08:44 PM ---Well I finally jumped into Pelles Version 11. However like the old lady with the shoe who had so many children she did not know what to do, I've got so many new warnings it is overwhelming as I try to resolve each.
So here is the first warning which I find a bit weird.
warning #2242: Call to 'memset' removed.
I've got many of these. Here is the case
--- Code: ---wchar_t HR[10]; // 10 wide characters
memset(HR,0,10); // fill 1st 10 bytes with 0 <- warning #2242: Call to 'memset' removed.
--- End code ---
So ok you might question why I do it - but why is it wrong?
--- End quote ---
This is simple to understand, global variables are by default initialized to 0, so the call to memset is redundant and automatically removed. The warning is just informational (you are using level2 warnings).
--- Quote from: John Z on April 24, 2022, 06:08:44 PM ---Then there is this to add, and confound, When this is the code:
--- Code: ---wchar_t HR[10]; // 10 wide characters
memset(HR,0,10); // fill 1st 10 bytes with 0
memset(HR,0,10); // fill 1st 10 bytes with 0
--- End code ---
There are NO warnings about removing memset .....
--- End quote ---
This behavior instead is difficult to understand, I can only suppose that the optimization, probably peephole optimization, stops at the 1st memset call?
John Z:
Thanks frankie & TimoVJL,
--- Quote from: frankie on April 24, 2022, 09:31:01 PM ---This is simple to understand, global variables are by default initialized to 0, so the call to memset is redundant and automatically removed. The warning is just informational (you are using level2 warnings).
--- End quote ---
BUT these are not global variables as I understand it. To demo that I put them also in a added procedure (other than MainDlgProc) just in case I'm missing something. Same results.
Yes, you are correct, Level 2 I always try to resolve all warnings to improve my knowledge/skills. Being a novice at Windows C programming it pays to be attentive to the warnings.
--- Quote from: TimoVJL on April 24, 2022, 09:07:06 PM ---optimization can replace memset with inline code.
--- End quote ---
You are right I turned off optimizations and the warnings disappeared for all cases. - Interesting..... the process of optimizing is resulting in the warning, not the original source code.
Thanks John
frankie:
--- Quote from: John Z on April 24, 2022, 10:41:32 PM ---
--- Quote from: frankie on April 24, 2022, 09:31:01 PM ---This is simple to understand, global variables are by default initialized to 0, so the call to memset is redundant and automatically removed. The warning is just informational (you are using level2 warnings).
--- End quote ---
BUT these are not global variables as I understand it. To demo that I put them also in a added procedure (other than MainDlgProc) just in case I'm missing something. Same results.
Yes, you are correct, Level 2 I always try to resolve all warnings to improve my knowledge/skills. Being a novice at Windows C programming it pays to be attentive to the warnings.
--- End quote ---
Yes you're right, and moreover they couldn't have been global because they were followed by code. I was wrong.
In any case the compiler always inlines the function I see, and if you compile with debug enabled the warnings automagically disappears...
It seems an informational message to tell you that a call is suppressed, useful in case of other function to know that eventual lateral effects are nulled, but probably spurious in this case.
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