Commit-ID: 37686b1353cfc30e127cef811959cdbcd0495d98 Gitweb: https://git.kernel.org/tip/37686b1353cfc30e127cef811959cdbcd0495d98 Author: Josh Poimboeuf <[email protected]> AuthorDate: Thu, 7 Mar 2019 11:48:02 -0600 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 3 Apr 2019 09:36:27 +0200
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]> --- include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 445348facea9..d58aa0db05f9 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -67,7 +67,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, .line = __LINE__, \ }; \ ______r = !!(cond); \ - ______f.miss_hit[______r]++; \ + ______r ? ______f.miss_hit[1]++ : ______f.miss_hit[0]++;\ ______r; \ })) #endif /* CONFIG_PROFILE_ALL_BRANCHES */
