Commit Graph

3 Commits

Author SHA1 Message Date
Fangrui Song 6ab8927931 [RISCV] Support clang -fpatchable-function-entry && GNU function attribute 'patchable_function_entry'
Similar to D72215 (AArch64) and D72220 (x86).

```
% clang -target riscv32 -march=rv64g -c -fpatchable-function-entry=2 a.c && llvm-objdump -dr a.o
...
0000000000000000 <main>:
       0: 13 00 00 00   nop
       4: 13 00 00 00   nop

% clang -target riscv32 -march=rv64gc -c -fpatchable-function-entry=2 a.c && llvm-objdump -dr a.o
...
00000002 <main>:
       2: 01 00         nop
       4: 01 00         nop
```

Recently the mainline kernel started to use -fpatchable-function-entry=8 for riscv (https://git.kernel.org/linus/afc76b8b80112189b6f11e67e19cf58301944814).

Differential Revision: https://reviews.llvm.org/D98610
2021-03-16 10:02:35 -07:00
Fangrui Song 69bf40c45f [Driver][CodeGen] Support -fpatchable-function-entry=N,M and __attribute__((patchable_function_entry(N,M))) where M>0
Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D73072
2020-01-23 17:02:54 -08:00
Fangrui Song f17ae668a9 [Driver][CodeGen] Add -fpatchable-function-entry=N[,0]
In the backend, this feature is implemented with the function attribute
"patchable-function-entry". Both the attribute and XRay use
TargetOpcode::PATCHABLE_FUNCTION_ENTER, so the two features are
incompatible.

Reviewed By: ostannard, MaskRay

Differential Revision: https://reviews.llvm.org/D72222
2020-01-10 09:57:39 -08:00