[WebAssembly] Support the new "Lime1" CPU (#112035)

This adds WebAssembly support for the new [Lime1 CPU].

First, this defines some new target features. These are subsets of
existing
features that reflect implementation concerns:

- "call-indirect-overlong" - implied by "reference-types"; just the
overlong
encoding for the `call_indirect` immediate, and not the actual reference
   types.

 - "bulk-memory-opt" - implied by "bulk-memory": just `memory.copy` and
   `memory.fill`, and not the other instructions in the bulk-memory
    proposal.

Next, this defines a new target CPU, "lime1", which enables
mutable-globals,
bulk-memory-opt, multivalue, sign-ext, nontrapping-fptoint,
extended-const,
and call-indirect-overlong. Unlike the default "generic" CPU, "lime1" is
meant
to be frozen, and followed up by "lime2" and so on when new features are
desired.

[Lime1 CPU]:
https://github.com/WebAssembly/tool-conventions/blob/main/Lime.md#lime1

---------

Co-authored-by: Heejin Ahn <aheejin@gmail.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
index d9d01bc..85e550a 100644
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -31,7 +31,7 @@ static constexpr Builtin::Info BuiltinInfo[] = {
 };
 
 static constexpr llvm::StringLiteral ValidCPUNames[] = {
-    {"mvp"}, {"bleeding-edge"}, {"generic"}};
+    {"mvp"}, {"bleeding-edge"}, {"generic"}, {"lime"}};
 
 StringRef WebAssemblyTargetInfo::getABI() const { return ABI; }
 
@@ -167,6 +167,17 @@ bool WebAssemblyTargetInfo::initFeatureMap(
     Features["reference-types"] = true;
     Features["sign-ext"] = true;
   };
+  auto addLime1Features = [&]() {
+    // Lime1:
+    // <https://github.com/WebAssembly/tool-conventions/blob/main/Lime.md#lime1>
+    Features["bulk-memory-opt"] = true;
+    Features["call-indirect-overlong"] = true;
+    Features["extended-const"] = true;
+    Features["multivalue"] = true;
+    Features["mutable-globals"] = true;
+    Features["nontrapping-fptoint"] = true;
+    Features["sign-ext"] = true;
+  };
   auto addBleedingEdgeFeatures = [&]() {
     addGenericFeatures();
     Features["atomics"] = true;
@@ -180,6 +191,8 @@ bool WebAssemblyTargetInfo::initFeatureMap(
   };
   if (CPU == "generic") {
     addGenericFeatures();
+  } else if (CPU == "lime1") {
+    addLime1Features();
   } else if (CPU == "bleeding-edge") {
     addBleedingEdgeFeatures();
   }