[llvm] r309611 - [sanitizer-coverage] don't instrument available_externally functions

[David Blaikie via llvm-commits]

On Mon, Jul 31, 2017 at 1:01 PM Kostya Serebryany via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: kcc
> Date: Mon Jul 31 13:00:22 2017
> New Revision: 309611
>
> URL: http://llvm.org/viewvc/llvm-project?rev=309611&view=rev
> Log:
> [sanitizer-coverage] don't instrument available_externally functions
>

I take it this happens long after inlining, etc? (usually I'd expect
various sanitizer instrumentation to happen early - so it could be inlined
& still tracked, etc (eg: you'd want to know you had function coverage at
one inlined site rather than believing there was no coverage at all) - so
it surprises me that you wouldn't want to instrument available_externally
functions so that when they were inlined the inlined version would be
appropriately instrumented too)


>
> Modified:
>     llvm/trunk/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
>     llvm/trunk/test/Instrumentation/SanitizerCoverage/tracing.ll
>
> Modified: llvm/trunk/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/SanitizerCoverage.cpp?rev=309611&r1=309610&r2=309611&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/Instrumentation/SanitizerCoverage.cpp Mon
> Jul 31 13:00:22 2017
> @@ -418,6 +418,9 @@ bool SanitizerCoverageModule::runOnFunct
>      return false; // Should not instrument sanitizer init functions.
>    if (F.getName().startswith("__sanitizer_"))
>      return false;  // Don't instrument __sanitizer_* callbacks.
> +  // Don't touch available_externally functions, their actual body is
> elewhere.
> +  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
> +    return false;
>    // Don't instrument MSVC CRT configuration helpers. They may run before
> normal
>    // initialization.
>    if (F.getName() == "__local_stdio_printf_options" ||
>
> Modified: llvm/trunk/test/Instrumentation/SanitizerCoverage/tracing.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/SanitizerCoverage/tracing.ll?rev=309611&r1=309610&r2=309611&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/Instrumentation/SanitizerCoverage/tracing.ll (original)
> +++ llvm/trunk/test/Instrumentation/SanitizerCoverage/tracing.ll Mon Jul
> 31 13:00:22 2017
> @@ -18,6 +18,12 @@ entry:
>    ret void
>  }
>
> +define available_externally void @external_bar(i32* %a) sanitize_address {
> +entry:
> +  ret void
> +}
> +
> +
>  ; CHECK_PC-LABEL: define void @foo
>  ; CHECK_PC: call void @__sanitizer_cov_trace_pc
>  ; CHECK_PC: call void @__sanitizer_cov_trace_pc
> @@ -33,6 +39,10 @@ entry:
>  ; CHECK_PC_GUARD: call void @__sanitizer_cov_trace_pc_guard
>  ; CHECK_PC_GUARD-NOT: call void @__sanitizer_cov_trace_pc
>  ; CHECK_PC_GUARD: ret void
> +; CHECK_PC_GUARD-LABEL: @external_bar
> +; CHECK_PC_GUARD-NOT: call void @__sanitizer_cov_trace_pc
> +; CHECK_PC_GUARD: ret void
> +
>  ; CHECK_PC_GUARD: call void @__sanitizer_cov_trace_pc_guard_init(i32*
> bitcast (i32** @__start___sancov_guards to i32*), i32* bitcast (i32**
> @__stop___sancov_guards to i32*))
>
>  ; CHECK_PC_GUARD_DARWIN-LABEL: define void @foo
>
>
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