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How do I use
-Wa,option
in GCC? What are all the options I can pass to the assembler? Is there a list of all GCC options?
For example, I found -Wa,-a,-ad here. What does it mean?
Always check the Documentation
-Wa,option
Pass option as an option to the assembler. If option contains commas, it is split into multiple options at the commas.
So in your case -a and -ad were passed to the assembler, what those do depend on your assembler. Gcc doesn't know what to do with system-specific assembler options so giving it the -Wa flag lets it know to just pass whatever follows through.
You can also find the documentation locally via man pages. To open the documentation on GNU's assembler, perform:
$ man 1 as
It will open:
AS(1) GNU Development Tools AS(1)
NAME
AS - the portable GNU assembler.
SYNOPSIS
as [-a[cdghlns][=file]] [--alternate] [-D]
[--compress-debug-sections] [--nocompress-debug-sections]
[--debug-prefix-map old=new]
[--defsym sym=val] [-f] [-g] [--gstabs]
[--gstabs+] [--gdwarf-2] [--gdwarf-sections]
[--help] [-I dir] [-J]
[-K] [-L] [--listing-lhs-width=NUM]
[--listing-lhs-width2=NUM] [--listing-rhs-width=NUM]
[--listing-cont-lines=NUM] [--keep-locals] [-o
objfile] [-R] [--reduce-memory-overheads] [--statistics]
[-v] [-version] [--version] [-W] [--warn]
[--fatal-warnings] [-w] [-x] [-Z] [@FILE]
[--size-check=[error|warning]]
[--target-help] [target-options]
[--|files ...]
...
Since these options are passed to the assembler, you need to check the man page for as, not gcc.
-a turns on assembly output listings (which is written to standard output), while -ad omits any debugging directive from the output listing.
In order to see a list of options of any command in bash, you can run the following command:
man COMMAND
In this case
man gcc
will reveal that -Wa,option means the following:
Pass option as an option to the assembler. If option contains commas,
it is split into multiple options at the commas.
