Re: [Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Michel Dänzer]

On 17/02/17 06:01 PM, Eero Tamminen wrote:
> Hi,
> 
> On 10.02.2017 02:59, Michel Dänzer wrote:
>> On 09/02/17 10:50 PM, Emil Velikov wrote:
>>> On 9 February 2017 at 08:07, Michel Dänzer  wrote:
 From: Michel Dänzer 

 Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
 -fno-rtti, which must be used if it's part of the llvm-config
 --cxxflags
 output. We don't want LLVM to dictate the flags we use, and it can even
 cause build failures, e.g. if LLVM and Mesa are built with different
 compilers.
> 
> Out of curiosity, where this stuff is applied?
> 
> (If you're removing all of them, result is hard to debug, non-optimized
> binary...)
> 
> 
>>> Yes, please !
>>> Reviewed-by: Emil Velikov 
>>
>>
>>> Out of curiosity:
>>> Are you speaking of personal experience ? What was stored in the
>>> c/cpp/cxx flags that triggered build failure ?
>>
>> Building LLVM with clang 4.0 resulted in llvm-config --cxxflags
>> containing -Wstring-conversion and -fcolor-diagnostics, which aren't
>> supported by gcc 6.3.
> 
> There are generic flags that have been supported by few decades, which
> are not going to change, like -O[1-3], -Wall, -g.  Only the specific
> optimization & warning flags are something that differ between compiler
> versions (as new ones get added).

strip_unwanted_llvm_flags() only affects LLVM_CXXFLAGS, so this change
doesn't remove any compiler flags used by Mesa itself, it just prevents
llvm-config from unnecessarily adding potentially harmful compiler flags
when compiling some LLVM related Mesa code.


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer
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Re: [Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Eero Tamminen]

Hi,

On 10.02.2017 02:59, Michel Dänzer wrote:

On 09/02/17 10:50 PM, Emil Velikov wrote:

On 9 February 2017 at 08:07, Michel Dänzer  wrote:

From: Michel Dänzer 

Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
-fno-rtti, which must be used if it's part of the llvm-config --cxxflags
output. We don't want LLVM to dictate the flags we use, and it can even
cause build failures, e.g. if LLVM and Mesa are built with different
compilers.


Out of curiosity, where this stuff is applied?

(If you're removing all of them, result is hard to debug, non-optimized 
binary...)




Yes, please !
Reviewed-by: Emil Velikov 




Out of curiosity:
Are you speaking of personal experience ? What was stored in the
c/cpp/cxx flags that triggered build failure ?


Building LLVM with clang 4.0 resulted in llvm-config --cxxflags
containing -Wstring-conversion and -fcolor-diagnostics, which aren't
supported by gcc 6.3.


There are generic flags that have been supported by few decades, which 
are not going to change, like -O[1-3], -Wall, -g.  Only the specific 
optimization & warning flags are something that differ between compiler 
versions (as new ones get added).



- Eero

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Re: [Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Michel Dänzer]

On 09/02/17 10:50 PM, Emil Velikov wrote:
> On 9 February 2017 at 08:07, Michel Dänzer  wrote:
>> From: Michel Dänzer 
>>
>> Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
>> -fno-rtti, which must be used if it's part of the llvm-config --cxxflags
>> output. We don't want LLVM to dictate the flags we use, and it can even
>> cause build failures, e.g. if LLVM and Mesa are built with different
>> compilers.
>>
> Yes, please !
> Reviewed-by: Emil Velikov 

Thanks!


> Out of curiosity:
> Are you speaking of personal experience ? What was stored in the
> c/cpp/cxx flags that triggered build failure ?

Building LLVM with clang 4.0 resulted in llvm-config --cxxflags
containing -Wstring-conversion and -fcolor-diagnostics, which aren't
supported by gcc 6.3.


-- 
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Libre software enthusiast | Mesa and X developer
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Re: [Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Emil Velikov]

On 9 February 2017 at 08:07, Michel Dänzer  wrote:
> From: Michel Dänzer 
>
> Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
> -fno-rtti, which must be used if it's part of the llvm-config --cxxflags
> output. We don't want LLVM to dictate the flags we use, and it can even
> cause build failures, e.g. if LLVM and Mesa are built with different
> compilers.
>
Yes, please !
Reviewed-by: Emil Velikov 

Out of curiosity:
Are you speaking of personal experience ? What was stored in the
c/cpp/cxx flags that triggered build failure ?

-Emil
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Re: [Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Marek Olšák]

Reviewed-by: Marek Olšák 

Marek

On Thu, Feb 9, 2017 at 9:07 AM, Michel Dänzer  wrote:
> From: Michel Dänzer 
>
> Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
> -fno-rtti, which must be used if it's part of the llvm-config --cxxflags
> output. We don't want LLVM to dictate the flags we use, and it can even
> cause build failures, e.g. if LLVM and Mesa are built with different
> compilers.
>
> While we're at it, eat any whitespace preceding dropped flags as well.
>
> Signed-off-by: Michel Dänzer 
> ---
>  configure.ac | 33 -
>  1 file changed, 12 insertions(+), 21 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index a6ceee95a3..87a751e2fa 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -894,27 +894,18 @@ llvm_add_target() {
>  # $1 is the llvm-config command with arguments.
>  strip_unwanted_llvm_flags() {
>  # Use \> (marks the end of the word)
> -echo `$1` | sed \
> --e 's/-march=\S*//g' \
> --e 's/-mtune=\S*//g' \
> --e 's/-mcpu=\S*//g' \
> --e 's/-DNDEBUG\>//g' \
> --e 's/-D_GNU_SOURCE\>//g' \
> --e 's/-pedantic\>//g' \
> --e 's/-Wcovered-switch-default\>//g' \
> --e 's/-O.\>//g' \
> --e 's/-g\>//g' \
> --e 's/-Wall\>//g' \
> --e 's/-Wcast-qual\>//g' \
> --e 's/-Woverloaded-virtual\>//g' \
> --e 's/-fcolor-diagnostics\>//g' \
> --e 's/-fdata-sections\>//g' \
> --e 's/-ffunction-sections\>//g' \
> --e 's/-fno-exceptions\>//g' \
> --e 's/-fomit-frame-pointer\>//g' \
> --e 's/-fvisibility-inlines-hidden\>//g' \
> --e 's/-fPIC\>//g' \
> --e 's/-fstack-protector-strong\>//g'
> +echo " `$1`" | sed \
> +-e 's/\s\+-m\S*//g' \
> +-e 's/\s\+-DNDEBUG\>//g' \
> +-e 's/\s\+-D_GNU_SOURCE\>//g' \
> +-e 's/\s\+-pedantic\>//g' \
> +-e 's/\s\+-W\S*//g' \
> +-e 's/\s\+-O\S*//g' \
> +-e 's/\s\+-g\S*//g' \
> +-e 's/-fno-rtti\>/-Fno-rtti/g' \
> +-e 's/\s\+-f\S*//g' \
> +-e 's/-Fno-rtti\>/-fno-rtti/g' \
> +-e 's/^ //'
>  }
>
>  llvm_set_environment_variables() {
> --
> 2.11.0
>
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[Mesa-dev] [PATCH] configure.ac: Drop LLVM compiler flags more radically

[Michel Dänzer]

From: Michel Dänzer 

Drop all -m*, -W*, -O*, -g* and -f* flags, with the exception of
-fno-rtti, which must be used if it's part of the llvm-config --cxxflags
output. We don't want LLVM to dictate the flags we use, and it can even
cause build failures, e.g. if LLVM and Mesa are built with different
compilers.

While we're at it, eat any whitespace preceding dropped flags as well.

Signed-off-by: Michel Dänzer 
---
 configure.ac | 33 -
 1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/configure.ac b/configure.ac
index a6ceee95a3..87a751e2fa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -894,27 +894,18 @@ llvm_add_target() {
 # $1 is the llvm-config command with arguments.
 strip_unwanted_llvm_flags() {
 # Use \> (marks the end of the word)
-echo `$1` | sed \
--e 's/-march=\S*//g' \
--e 's/-mtune=\S*//g' \
--e 's/-mcpu=\S*//g' \
--e 's/-DNDEBUG\>//g' \
--e 's/-D_GNU_SOURCE\>//g' \
--e 's/-pedantic\>//g' \
--e 's/-Wcovered-switch-default\>//g' \
--e 's/-O.\>//g' \
--e 's/-g\>//g' \
--e 's/-Wall\>//g' \
--e 's/-Wcast-qual\>//g' \
--e 's/-Woverloaded-virtual\>//g' \
--e 's/-fcolor-diagnostics\>//g' \
--e 's/-fdata-sections\>//g' \
--e 's/-ffunction-sections\>//g' \
--e 's/-fno-exceptions\>//g' \
--e 's/-fomit-frame-pointer\>//g' \
--e 's/-fvisibility-inlines-hidden\>//g' \
--e 's/-fPIC\>//g' \
--e 's/-fstack-protector-strong\>//g'
+echo " `$1`" | sed \
+-e 's/\s\+-m\S*//g' \
+-e 's/\s\+-DNDEBUG\>//g' \
+-e 's/\s\+-D_GNU_SOURCE\>//g' \
+-e 's/\s\+-pedantic\>//g' \
+-e 's/\s\+-W\S*//g' \
+-e 's/\s\+-O\S*//g' \
+-e 's/\s\+-g\S*//g' \
+-e 's/-fno-rtti\>/-Fno-rtti/g' \
+-e 's/\s\+-f\S*//g' \
+-e 's/-Fno-rtti\>/-fno-rtti/g' \
+-e 's/^ //'
 }
 
 llvm_set_environment_variables() {
-- 
2.11.0

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