60
votes
3
answers
2.7K
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Possible GCC bug when returning struct from a function
I believe I found a bug in GCC while implementing O'Neill's PCG PRNG. (Initial code on Godbolt'
65
votes
3
answers
3K
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How do you use gcc to generate assembly code in Intel syntax?
The gcc -S option will generate assembly code in AT&T syntax, is there a way to generate files in Intel sy
50
votes
3
answers
1.8K
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Why does GCC generate such radically different assembly for nearly the same C code?
While writing an optimized ftol function I found some very odd behaviour in GCC 4.6.1. Let me show you the cod
62
votes
5
answers
2.4K
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Why does GCC use multiplication by a strange number in implementing integer division?
I've been reading about div and mul assembly operations, and I decided to see them in action by writing a
48
votes
10
answers
1.6K
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Using GCC to produce readable assembly?
I was wondering how to use GCC on my C source file to dump a mnemonic version of the machine code so I could s
55
votes
17
answers
1.5K
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How do you get assembler output from C/C++ source in gcc?
How does one do this? If I want to analyze how something is getting compiled, how would I get the emitted ass
58
votes
12
answers
923
views
Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?
I am doing some numerical optimization on a scientific application. One thing I noticed is that GCC will optim
62
votes
5
answers
1.3K
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Why does the C preprocessor interpret the word "linux" as the constant "1"?
Why does the C preprocessor in GCC interpret the word linux (small letters) as the constant 1? test.c: #incl
51
votes
1
answers
505
views
GCC: what's the default value when a symbol is defined on command line?
The following test code shows that a -DMY_FLAG on command line gives the symbol MY_FLAG a non-zero value, acco
