Leverage the method OpenCL uses that adds C intrinsics when the lookup
failed. There is no need to define C intrinsics in the header file any
more. It could help to avoid the large header file to speed up the
compilation of RVV source code. Besides that, only the C intrinsics used
by the users will be added into the declaration table.
This patch is based on https://reviews.llvm.org/D103228 and inspired by
OpenCL implementation.
### Experimental Results
#### TL;DR:
- Binary size of clang increase ~200k, which is +0.07% for debug build and +0.13% for release build.
- Single file compilation speed up ~33x for debug build and ~8.5x for release build
- Regression time reduce ~10% (`ninja check-all`, enable all targets)
#### Header size change
```
| size | LoC |
------------------------------
Before | 4,434,725 | 69,749 |
After | 6,140 | 162 |
```
#### Single File Compilation Time
Testcase:
```
#include <riscv_vector.h>
vint32m1_t test_vadd_vv_vfloat32m1_t(vint32m1_t op1, vint32m1_t op2, size_t vl) {
return vadd(op1, op2, vl);
}
```
##### Debug build:
Before:
```
real 0m19.352s
user 0m19.252s
sys 0m0.092s
```
After:
```
real 0m0.576s
user 0m0.552s
sys 0m0.024s
```
~33x speed up for debug build
##### Release build:
Before:
```
real 0m0.773s
user 0m0.741s
sys 0m0.032s
```
After:
```
real 0m0.092s
user 0m0.080s
sys 0m0.012s
```
~8.5x speed up for release build
#### Regression time
Note: the failed case is `tools/llvm-debuginfod-find/debuginfod.test` which is unrelated to this patch.
##### Debug build
Before:
```
Testing Time: 1358.38s
Skipped : 11
Unsupported : 446
Passed : 75767
Expectedly Failed: 190
Failed : 1
```
After
```
Testing Time: 1220.29s
Skipped : 11
Unsupported : 446
Passed : 75767
Expectedly Failed: 190
Failed : 1
```
##### Release build
Before:
```
Testing Time: 381.98s
Skipped : 12
Unsupported : 1407
Passed : 74765
Expectedly Failed: 176
Failed : 1
```
After:
```
Testing Time: 346.25s
Skipped : 12
Unsupported : 1407
Passed : 74765
Expectedly Failed: 176
Failed : 1
```
#### Binary size of clang
##### Debug build
Before
```
text data bss dec hex filename
335261851 12726004 552812 348540667 14c64efb bin/clang
```
After
```
text data bss dec hex filename
335442803 12798708 552940 348794451 14ca2e53 bin/clang
```
+253K, +0.07% code size
##### Release build
Before
```
text data bss dec hex filename
144123975 8374648 483140 152981763 91e5103 bin/clang
```
After
```
text data bss dec hex filename
144255762 8447296 483268 153186326 9217016 bin/clang
```
+204K, +0.13%
Authored-by: Kito Cheng <kito.cheng@sifive.com>
Co-Authored-by: Hsiangkai Wang <kai.wang@sifive.com>
Reviewed By: khchen, aaron.ballman
Differential Revision: https://reviews.llvm.org/D111617
7a5cb15ea6