llvm dev - Jan 2020 - how to enable exceptions for one component

LLVM_ENABLE_EH is a global option, not a target property. For a single target,
it’s more appropriate to use LLVM_REQUIRES_EH, which is also a variable you’ll
need to set before calling add_llvm_component_library. You can do something like

set(LLVM_REQUIRES_EH_ORIGINAL ${LLVM_REQUIRES_EH})
set(LLVM_REQUIRES_EH YES)
add_llvm_component_library(LLVMTargetLibrary
  TargetFile1.cpp
  TargetFile2.cpp
  )
set(LLVM_REQUIRES_EH ${LLVM_REQUIRES_EH_ORIGINAL})

The implementation for this functionality lives in
llvm/cmake/modules/AddLLVM.cmake [1], where you can see what effect
LLVM_REQUIRES_EH has.

[1]
https://github.com/llvm/llvm-project/blob/master/llvm/cmake/modules/AddLLVM.cmake


From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of
"Davis, Alan via llvm-dev" <llvm-dev at lists.llvm.org>
Reply-To: "Davis, Alan" <adavis at ti.com>
Date: Sunday, January 12, 2020 at 5:09 PM
To: LLVM Developers Mailing List <llvm-dev at lists.llvm.org>
Subject: [llvm-dev] how to enable exceptions for one component

I’d like to enable exceptions for a single target-specific LLVM component which
is built as library. That is, I’d like to allow it to throw exceptions to its
(non-LLVM) client to signal errors. In the CMakeLists.txt for the component, I
tried:

add_llvm_component_library(LLVMTargetLibrary
  TargetFile1.cpp
  TargetFile2.cpp
  )

set_property(TARGET LLVMTargetLibrary PROPERTY LLVM_ENABLE_EH ON)

But it still compiles with –fno-exceptions.

Thanks for any advice.

-Alan
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Perfect, thanks.
For the record, I had to also set/reset LLVM_REQUIRES_RTTI in the same way.

From: Shoaib Meenai [mailto:smeenai at fb.com]
Sent: Monday, January 13, 2020 1:01 AM
To: Davis, Alan; LLVM Developers Mailing List
Subject: [EXTERNAL] Re: [llvm-dev] how to enable exceptions for one component

LLVM_ENABLE_EH is a global option, not a target property. For a single target,
it’s more appropriate to use LLVM_REQUIRES_EH, which is also a variable you’ll
need to set before calling add_llvm_component_library. You can do something like

set(LLVM_REQUIRES_EH_ORIGINAL ${LLVM_REQUIRES_EH})
set(LLVM_REQUIRES_EH YES)
add_llvm_component_library(LLVMTargetLibrary
  TargetFile1.cpp
  TargetFile2.cpp
  )
set(LLVM_REQUIRES_EH ${LLVM_REQUIRES_EH_ORIGINAL})

The implementation for this functionality lives in
llvm/cmake/modules/AddLLVM.cmake [1], where you can see what effect
LLVM_REQUIRES_EH has.

[1]
https://github.com/llvm/llvm-project/blob/master/llvm/cmake/modules/AddLLVM.cmake


From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of
"Davis, Alan via llvm-dev" <llvm-dev at lists.llvm.org>
Reply-To: "Davis, Alan" <adavis at ti.com>
Date: Sunday, January 12, 2020 at 5:09 PM
To: LLVM Developers Mailing List <llvm-dev at lists.llvm.org>
Subject: [llvm-dev] how to enable exceptions for one component

I’d like to enable exceptions for a single target-specific LLVM component which
is built as library. That is, I’d like to allow it to throw exceptions to its
(non-LLVM) client to signal errors. In the CMakeLists.txt for the component, I
tried:

add_llvm_component_library(LLVMTargetLibrary
  TargetFile1.cpp
  TargetFile2.cpp
  )

set_property(TARGET LLVMTargetLibrary PROPERTY LLVM_ENABLE_EH ON)

But it still compiles with –fno-exceptions.

Thanks for any advice.

-Alan
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