[llvm] [SandboxVec][BottomUpVec] Implement pack of scalars (PR #115549)

[via llvm-commits]

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@@ -108,6 +108,31 @@ class VecUtils {
     }
     return LowestI;
   }
+  /// If all values in \p Bndl are of the same scalar type then return it,
+  /// otherwise return nullptr.
+  static Type *tryGetCommonScalarType(ArrayRef<Value *> Bndl) {
+    Value *V0 = Bndl[0];
+    Type *Ty0 = Utils::getExpectedType(V0);
+    Type *ScalarTy = VecUtils::getElementType(Ty0);
+    for (auto *V : drop_begin(Bndl)) {
+      Type *NTy = Utils::getExpectedType(V);
+      Type *NScalarTy = VecUtils::getElementType(NTy);
+      if (NScalarTy != ScalarTy)
+        return nullptr;
+    }
+    return ScalarTy;
+  }
+
+  /// Similar to tryGetCommonScalarType() but will assert that there is a common
+  /// type. So this is faster in release builds as it won't iterate through the
+  /// values.
+  static Type *getCommonScalarType(ArrayRef<Value *> Bndl) {
+    Value *V0 = Bndl[0];
+    Type *Ty0 = Utils::getExpectedType(V0);
+    Type *ScalarTy = VecUtils::getElementType(Ty0);
+    assert(tryGetCommonScalarType(Bndl) && "Expected common scalar type!");
+    return ScalarTy;
+  }
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vporpo wrote:

`tryGetCommonScalarType(Bnd)` is expensive as it goes through the whole array so I want this to be enabled only as an assertion in the DEBUG build.

https://github.com/llvm/llvm-project/pull/115549