This stack of changes introduces `llvm-profgen` utility which generates a profile data file from given perf script data files for sample-based PGO. It’s part of(not only) the CSSPGO work. Specifically to support context-sensitive with/without pseudo probe profile, it implements a series of functionalities including perf trace parsing, instruction symbolization, LBR stack/call frame stack unwinding, pseudo probe decoding, etc. Also high throughput is achieved by multiple levels of sample aggregation and compatible format with one stop is generated at the end. Please refer to: https://groups.google.com/g/llvm-dev/c/1p1rdYbL93s for the CSSPGO RFC.
This change adds the support of instruction symbolization. Given the RVA on an instruction pointer, a full calling context can be printed side-by-side with the disassembly code.
E.g.
```
Disassembly of section .text [0x0, 0x4a]:
<funcA>:
0: mov eax, edi funcA:0
2: mov ecx, dword ptr [rip] funcLeaf:2 @ funcA:1
8: lea edx, [rcx + 3] fib:2 @ funcLeaf:2 @ funcA:1
b: cmp ecx, 3 fib:2 @ funcLeaf:2 @ funcA:1
e: cmovl edx, ecx fib:2 @ funcLeaf:2 @ funcA:1
11: sub eax, edx funcLeaf:2 @ funcA:1
13: ret funcA:2
14: nop word ptr cs:[rax + rax]
1e: nop
<funcLeaf>:
20: mov eax, edi funcLeaf:1
22: mov ecx, dword ptr [rip] funcLeaf:2
28: lea edx, [rcx + 3] fib:2 @ funcLeaf:2
2b: cmp ecx, 3 fib:2 @ funcLeaf:2
2e: cmovl edx, ecx fib:2 @ funcLeaf:2
31: sub eax, edx funcLeaf:2
33: ret funcLeaf:3
34: nop word ptr cs:[rax + rax]
3e: nop
<fib>:
40: lea eax, [rdi + 3] fib:2
43: cmp edi, 3 fib:2
46: cmovl eax, edi fib:2
49: ret fib:8
```
Test Plan:
ninja check-llvm
Reviewed By: wenlei, wmi
Differential Revision: https://reviews.llvm.org/D89715
wlei