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clang: -fno-pie should not imply -fdirect-access-external-data for loongarch*-linux #71645

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xry111 opened this issue Nov 8, 2023 · 4 comments · Fixed by #72221
Closed

clang: -fno-pie should not imply -fdirect-access-external-data for loongarch*-linux #71645

xry111 opened this issue Nov 8, 2023 · 4 comments · Fixed by #72221
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backend:loongarch clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl'

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@xry111
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xry111 commented Nov 8, 2023

loongarch*-linux does not and will not support copy relocation, so -fdirect-access-external-data generally does not work for any dynamic-linked executable.
@github-actions github-actions bot added the clang Clang issues not falling into any other category label Nov 8, 2023
@xry111
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xry111 commented Nov 8, 2023 

xry111@nanmen2 ~ $ cat t1.c
extern char **environ;

int main()
{
  __builtin_printf("%10s\n", environ[0]);
}
xry111@nanmen2 ~ $ clang t1.c -fdirect-access-external-data -O2
xry111@nanmen2 ~ $ ./a.out 
Bus error (core dumped)

@xry111
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xry111 commented Nov 8, 2023

@xen0n @SixWeining

@EugeneZelenko EugeneZelenko added clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' backend:loongarch and removed clang Clang issues not falling into any other category labels Nov 8, 2023
@llvmbot
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llvmbot commented Nov 8, 2023

@llvm/issue-subscribers-clang-driver

Author: Xi Ruoyao (xry111)

loongarch*-linux does not and will not support copy relocation, so -fdirect-access-external-data generally does not work for any dynamic-linked executable.

@SixWeining
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SixWeining commented Nov 9, 2023 •
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add @wangleiat

@heiher heiher self-assigned this Nov 10, 2023
heiher added a commit to heiher/llvm-project that referenced this issue Nov 10, 2023
@heiher
[clang][LoongArch] Don't imply -fdirect-access-external-data for non-PIC
09bce09 
LoongArch does not and will not support copy relocation, so non-PIC code
defaults to -fno-direct-access-external-data.

Explicit `-fdirect-access-external-data` is acceptable, for example if
the code is writable.

Reported-by: Xi Ruoyao <[email protected]>
Signed-off-by: WANG Rui <[email protected]>

Fixes llvm#71645
@xry111 xry111 mentioned this issue Nov 10, 2023
Closed
MaskRay added a commit to MaskRay/llvm-project that referenced this issue Nov 14, 2023
@MaskRay
[Driver] Default LoongArch to -fno-direct-access-external-data for no…
57fe953 
…n-PIC

For -fno-pic, if an extern variable is defined in a DSO, a copy
relocation will be needed. However, loongarch*-linux does not and will
not support copy relocations.

Change Driver to default to -fno-direct-access-external-data for
LoongArch && non-PIC.
Keep Frontend conditions unchanged (-fdirect-access-external-data ||
-fno-direct-access-external-data && PIC>0 => direct access).

Fix llvm#71645
@MaskRay MaskRay mentioned this issue Nov 14, 2023
Merged
MaskRay added a commit that referenced this issue Nov 14, 2023
@MaskRay
[Driver] Default LoongArch to -fno-direct-access-external-data for no…
47eeee2 
…n-PIC (#72221)

For -fno-pic, if an extern variable is defined in a DSO, a copy
relocation will be needed. However, loongarch*-linux does not and will
not support copy relocations.

Change Driver to default to -fno-direct-access-external-data for
LoongArch && non-PIC.
Keep Frontend conditions unchanged (-fdirect-access-external-data ||
-fno-direct-access-external-data && PIC>0 => direct access).

Fix #71645
@heiher heiher mentioned this issue Nov 19, 2023
Closed
zahiraam pushed a commit to zahiraam/llvm-project that referenced this issue Nov 20, 2023
@MaskRay @zahiraam
[Driver] Default LoongArch to -fno-direct-access-external-data for no…
afd5b60 
…n-PIC (llvm#72221)

For -fno-pic, if an extern variable is defined in a DSO, a copy
relocation will be needed. However, loongarch*-linux does not and will
not support copy relocations.

Change Driver to default to -fno-direct-access-external-data for
LoongArch && non-PIC.
Keep Frontend conditions unchanged (-fdirect-access-external-data ||
-fno-direct-access-external-data && PIC>0 => direct access).

Fix llvm#71645
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