[-Wunsafe-buffer-usage] Reland '[Clang] Optimize -Wunsafe-buffer-usage (llvm#125492)' (#10340)

[Clang] Optimize -Wunsafe-buffer-usage. (llvm#125492)

The Clang disgnostic `-Wunsafe-buffer-usage` was adding up to +15%
compilation time when used. Profiling showed that most of the overhead
comes from the use of ASTMatchers.

This change replaces the ASTMatcher infrastructure with simple matching
functions and keeps the functionality unchanged. It reduces the overhead
added by `-Wunsafe-buffer-usage` by 87.8%, leaving a negligible
additional compilation time of 1.7% when the diagnostic is used.

**Old version without -Wunsafe-buffer-usage:**
```
$ hyperfine -i -w 1 --runs 5 '/tmp/old_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20'
Benchmark 1: /tmp/old_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20
  Time (mean ± σ):     231.035 s ±  3.210 s    [User: 229.134 s, System: 1.704 s]
  Range (min … max):   228.751 s … 236.682 s    5 runs
```

**Old version with -Wunsafe-buffer-usage:**
```
$ hyperfine -i -w 1 --runs 10 '/tmp/old_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20 -Wunsafe-buffer-usage'
Benchmark 1: /tmp/old_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20 -Wunsafe-buffer-usage
  Time (mean ± σ):     263.840 s ±  0.854 s    [User: 262.043 s, System: 1.575 s]
  Range (min … max):   262.442 s … 265.142 s    10 runs
```

**New version with -Wunsafe-buffer-usage:**
```
$ hyperfine -i -w 1 --runs 10 '/tmp/new_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20 -Wunsafe-buffer-usage'
Benchmark 1: /tmp/new_clang -c -std=c++20 /tmp/preprocessed.cc -ferror-limit=20 -Wunsafe-buffer-usage
  Time (mean ± σ):     235.169 s ±  1.408 s    [User: 233.406 s, System: 1.561 s]
  Range (min … max):   232.221 s … 236.792 s    10 runs
```
 Conflicts:
	clang/lib/Analysis/UnsafeBufferUsage.cpp

[-Wunsafe-buffer-usage] Correctly merge "[Clang] Optimize -Wunsafe-buffer-usage"

The upstream commit 18a0bd4fc387e16c4bd342c6d3a83366e2ec2bc1 replaces
ASTMatchers in `UnsafeBufferUsage.cpp` with plain AST matching.  It
improves the performance and makes the code easier to debug and
optimize.

This commit resolves massive conflicts introduced in
18a0bd4fc387e16c4bd342c6d3a83366e2ec2bc1.

(rdar://147529568)

Co-authored-by: Ivana Ivanovska <[email protected]>

Author: ziqingluo-90

clang/include/clang/Analysis/Analyses/UnsafeBufferUsageGadgets.def

@@ -24,6 +24,12 @@
 #define WARNING_OPTIONAL_GADGET(name) WARNING_GADGET(name)
 #endif
 
+/// A `WARNING_GADGET` subset, each of which corresponds to an unsafe
+/// interaction with bounds-attributed constructs
+#ifndef WARNING_BOUNDS_SAFETY_GADGET
+#define WARNING_BOUNDS_SAFETY_GADGET(name) WARNING_GADGET(name)
+#endif
+
 /// Safe gadgets correspond to code patterns that aren't unsafe but need to be
 /// properly recognized in order to emit correct warnings and fixes over unsafe
 /// gadgets.
@@ -39,8 +45,8 @@ WARNING_GADGET(UnsafeBufferUsageAttr)
 WARNING_GADGET(UnsafeBufferUsageCtorAttr)
 WARNING_GADGET(DataInvocation)
 // TO_UPSTREAM(BoundsSafety) ON
-WARNING_GADGET(CountAttributedPointerArgument)
-WARNING_GADGET(SinglePointerArgument)
+WARNING_BOUNDS_SAFETY_GADGET(CountAttributedPointerArgument)
+WARNING_BOUNDS_SAFETY_GADGET(SinglePointerArgument)
 // TO_UPSTREAM(BoundsSafety) OFF
 WARNING_OPTIONAL_GADGET(UnsafeLibcFunctionCall)
 WARNING_OPTIONAL_GADGET(SpanTwoParamConstructor) // Uses of `std::span(arg0, arg1)`
@@ -58,4 +64,5 @@ FIXABLE_GADGET(PointerInit)
 #undef FIXABLE_GADGET
 #undef WARNING_GADGET
 #undef WARNING_OPTIONAL_GADGET
+#undef WARNING_BOUNDS_SAFETY_GADGET
 #undef GADGET