Commit-ID: 37686b1353cfc30e127cef811959cdbcd0495d98 Gitweb: https://git.kernel.org/tip/37686b1353cfc30e127cef811959cdbcd0495d98 Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> AuthorDate: Thu, 7 Mar 2019 11:48:02 -0600 Committer: Ingo Molnar <mingo@xxxxxxxxxx> 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 <peterz@xxxxxxxxxxxxx> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: brgerst@xxxxxxxxx Cc: catalin.marinas@xxxxxxx Cc: dvlasenk@xxxxxxxxxx Cc: dvyukov@xxxxxxxxxx Cc: hpa@xxxxxxxxx Cc: james.morse@xxxxxxx Cc: julien.thierry@xxxxxxx Cc: luto@xxxxxxxxxxxxxx Cc: luto@xxxxxxxxxx Cc: rostedt@xxxxxxxxxxx Cc: valentin.schneider@xxxxxxx Cc: will.deacon@xxxxxxx Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@treble Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- 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 */
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