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llvm-mirror/bindings/go
Marco Elver b835b9cf36 [SanitizeCoverage] Add support for NoSanitizeCoverage function attribute
We really ought to support no_sanitize("coverage") in line with other
sanitizers. This came up again in discussions on the Linux-kernel
mailing lists, because we currently do workarounds using objtool to
remove coverage instrumentation. Since that support is only on x86, to
continue support coverage instrumentation on other architectures, we
must support selectively disabling coverage instrumentation via function
attributes.

Unfortunately, for SanitizeCoverage, it has not been implemented as a
sanitizer via fsanitize= and associated options in Sanitizers.def, but
rolls its own option fsanitize-coverage. This meant that we never got
"automatic" no_sanitize attribute support.

Implement no_sanitize attribute support by special-casing the string
"coverage" in the NoSanitizeAttr implementation. To keep the feature as
unintrusive to existing IR generation as possible, define a new negative
function attribute NoSanitizeCoverage to propagate the information
through to the instrumentation pass.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=49035

Reviewed By: vitalybuka, morehouse

Differential Revision: https://reviews.llvm.org/D102772
2021-05-25 12:57:14 +02:00
..
llvm
build.sh
conftest.go
README.txt

This directory contains LLVM bindings for the Go programming language
(http://golang.org).

Prerequisites
-------------

* Go 1.2+.
* CMake (to build LLVM).

Using the bindings
------------------

The package path "llvm.org/llvm/bindings/go/llvm" can be used to
import the latest development version of LLVM from SVN. Paths such as
"llvm.org/llvm.v36/bindings/go/llvm" refer to released versions of LLVM.

It is recommended to use the "-d" flag with "go get" to download the
package or a dependency, as an additional step is required to build LLVM
(see "Building LLVM" below).

Building LLVM
-------------

The script "build.sh" in this directory can be used to build LLVM and prepare
it to be used by the bindings. If you receive an error message from "go build"
like this:

    ./analysis.go:4:84: fatal error: llvm-c/Analysis.h: No such file or directory
     #include <llvm-c/Analysis.h> // If you are getting an error here read bindings/go/README.txt

or like this:

    ./llvm_dep.go:5: undefined: run_build_sh

it means that LLVM needs to be built or updated by running the script.

    $ $GOPATH/src/llvm.org/llvm/bindings/go/build.sh

Any command line arguments supplied to the script are passed to LLVM's CMake
build system. A good set of arguments to use during development are:

    $ $GOPATH/src/llvm.org/llvm/bindings/go/build.sh -DCMAKE_BUILD_TYPE=Debug -DLLVM_TARGETS_TO_BUILD=host -DBUILD_SHARED_LIBS=ON

Note that CMake keeps a cache of build settings so once you have built
LLVM there is no need to pass these arguments again after updating.

Alternatively, you can build LLVM yourself, but you must then set the
CGO_CPPFLAGS, CGO_CXXFLAGS and CGO_LDFLAGS environment variables:

    $ export CGO_CPPFLAGS="`/path/to/llvm-build/bin/llvm-config --cppflags`"
    $ export CGO_CXXFLAGS=-std=c++14
    $ export CGO_LDFLAGS="`/path/to/llvm-build/bin/llvm-config --ldflags --libs --system-libs all`"
    $ go build -tags byollvm

If you see a compilation error while compiling your code with Go 1.9.4 or later as follows,

    go build llvm.org/llvm/bindings/go/llvm: invalid flag in #cgo LDFLAGS: -Wl,-headerpad_max_install_names

you need to setup $CGO_LDFLAGS_ALLOW to allow a compiler to specify some linker options:

    $ export CGO_LDFLAGS_ALLOW='-Wl,(-search_paths_first|-headerpad_max_install_names)'