[clang] Introduce `SemaRISCV` (#92682)

This patch moves `Sema` functions that are specific for RISC-V into the
new `SemaRISCV` class. This continues previous efforts to split `Sema`
up. Additional context can be found in
https://github.com/llvm/llvm-project/pull/84184.

This PR is somewhat different from previous PRs on this topic:
1. Splitting out target-specific functions wasn't previously discussed.
It felt quite natural to do, though.
2. I had to make some static function in `SemaChecking.cpp` member
functions of `Sema` in order to use them in `SemaRISCV`.
3. I dropped "RISCV" from identifiers, but decided to leave "RVV"
(RISC-V "V" vector extensions) intact. I think it's an idiomatic
abbreviation at this point, but I'm open to input from contributors in
that area.
4. I repurposed `SemaRISCVVectorLookup.cpp` for `SemaRISCV`.

I think this was a successful experiment, which both helps the goal of
splitting `Sema` up, and shows a way to approach `SemaChecking.cpp`,
which I wasn't sure how to approach before. As we move more
target-specific function out of there, we'll gradually make the checking
"framework" inside `SemaChecking.cpp` public, which is currently a whole
bunch of static functions. This would enable us to move more functions
outside of `SemaChecking.cpp`.

1 files changed, 6 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index e4d4cd7..ef0a655 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -34,6 +34,7 @@
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaInternal.h"
+#include "clang/Sema/SemaRISCV.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "llvm/ADT/STLExtras.h"
@@ -945,13 +946,13 @@ bool Sema::LookupBuiltin(LookupResult &R) {
         }
       }
 
-      if (DeclareRISCVVBuiltins || DeclareRISCVSiFiveVectorBuiltins) {
-        if (!RVIntrinsicManager)
-          RVIntrinsicManager = CreateRISCVIntrinsicManager(*this);
+      if (RISCV().DeclareRVVBuiltins || RISCV().DeclareSiFiveVectorBuiltins) {
+        if (!RISCV().IntrinsicManager)
+          RISCV().IntrinsicManager = CreateRISCVIntrinsicManager(*this);
 
-        RVIntrinsicManager->InitIntrinsicList();
+        RISCV().IntrinsicManager->InitIntrinsicList();
 
-        if (RVIntrinsicManager->CreateIntrinsicIfFound(R, II, PP))
+        if (RISCV().IntrinsicManager->CreateIntrinsicIfFound(R, II, PP))
           return true;
       }