tracing: Improve "if" macro code generation

With CONFIG_PROFILE_ALL_BRANCHES=y, the "if" macro converts the
conditional to an array index.  This can cause GCC to create horrible
code.  When there are nested ifs, the generated code uses register
values to encode branching decisions.

Make it easier for GCC to optimize by keeping the conditional as a
conditional rather than converting it to an integer.  This shrinks the
generated code quite a bit, and also makes the code sane enough for
objtool to understand.

Reported-by: Peter Zijlstra <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@treble
Signed-off-by: Ingo Molnar <[email protected]>

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