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MINOR: debug: add a new DISGUISE() macro to pass a value as identity

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This does exactly the same as ALREADY_CHECKED() but does it inline,
returning an identical copy of the scalar variable without letting
the compiler know how it might have been transformed. This can
forcefully disable certain null-pointer checks or result checks when
known undesirable. Typically forcing a crash with *(DISGUISE(NULL))=0
will not cause a null-deref warning.
This commit is contained in:
Willy Tarreau 2020-03-14 10:42:26 +01:00
parent 663825e5d0
commit f401668306
1 changed files with 5 additions and 0 deletions
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5
include/common/compiler.h
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@ -77,6 +77,11 @@
*/
#define ALREADY_CHECKED(p) do { asm("" : "=rm"(p) : "0"(p)); } while (0)
/* same as above but to be used to pass the input value to the output but
* without letting the compiler know about its initial properties.
*/
#define DISGUISE(v) ({ typeof(v) __v = (v); ALREADY_CHECKED(__v); __v; })
/*
* Gcc >= 3 provides the ability for the program to give hints to the
* compiler about what branch of an if is most likely to be taken. This