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doc: Remove GCC_ISSUES

This file is outdated, the mentioned issue is no longer there for
newer gcc versions - for bitcoin we haven't had to specify any special
optimization flag overrides for a long time (we compile using -O2).
pull/126/head
Wladimir J. van der Laan 3 years ago
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# The Problem

gcc sometimes generates slightly different code with the same semantics.

## Optimizations

The following optimizer flags reduce non-determinism when compiling wxWidgets:

-fno-tree-loop-optimize
-fno-trapping-math
-fno-tree-reassoc

## Left Over

Even with the above flags, the compiler still generates this difference in one out of 100 builds of wxWidgets:

monolib_property.o: elf64-elf_x86_64

aef7: 00
aef8: 45 31 f6 xor %r14d,%r14d
aefb: 48 8d 84 24 50 06 00 00 lea 0x650(%rsp),%rax
- af03: c6 44 24 67 00 movb $0x0,0x67(%rsp)
- af08: 48 83 c2 10 add $0x10,%rdx
- af0c: 48 83 c1 10 add $0x10,%rcx
- af10: 48 81 7c 24 08 ff ff ff cmpq $0xffffff,0x8(%rsp)
- af18: 00
- af19: c6 44 24 47 00 movb $0x0,0x47(%rsp)
- af1e: c7 44 24 24 00 00 00 00 movl $0x0,0x24(%rsp)
+ af03: c7 44 24 24 00 00 00 00 movl $0x0,0x24(%rsp)
+ af0b: 48 83 c2 10 add $0x10,%rdx
+ af0f: 48 83 c1 10 add $0x10,%rcx
+ af13: 48 81 7c 24 08 ff ff ff cmpq $0xffffff,0x8(%rsp)
+ af1b: 00
+ af1c: c6 44 24 47 00 movb $0x0,0x47(%rsp)
+ af21: c6 44 24 67 00 movb $0x0,0x67(%rsp)
af26: 4c 8d bc 24 28 03 00 00 lea 0x328(%rsp),%r15
af2e: 48 89 44 24 10 mov %rax,0x10(%rsp)
af33: 48 89 54 24 78 mov %rdx,0x78(%rsp)


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