[clang] [CIR] Upstream basic alloca and load support (PR #128792)

[Erich Keane via cfe-commits]

================
@@ -115,6 +115,149 @@ def ConstantOp : CIR_Op<"const",
   let hasFolder = 1;
 }
 
+//===----------------------------------------------------------------------===//
+// AllocaOp
+//===----------------------------------------------------------------------===//
+
+class AllocaTypesMatchWith<string summary, string lhsArg, string rhsArg,
+                     string transform, string comparator = "std::equal_to<>()">
+  : PredOpTrait<summary, CPred<
+      comparator # "(" #
+      !subst("$_self", "$" # lhsArg # ".getType()", transform) #
+             ", $" # rhsArg # ")">> {
+  string lhs = lhsArg;
+  string rhs = rhsArg;
+  string transformer = transform;
+}
+
+def AllocaOp : CIR_Op<"alloca", [
+  AllocaTypesMatchWith<"'allocaType' matches pointee type of 'addr'",
+                 "addr", "allocaType",
+                 "cast<PointerType>($_self).getPointee()">,
+                 DeclareOpInterfaceMethods<PromotableAllocationOpInterface>]> {
+  let summary = "Defines a scope-local variable";
+  let description = [{
+    The `cir.alloca` operation defines a scope-local variable.
+
+    The presence `init` attribute indicates that the local variable represented
+    by this alloca was originally initialized in C/C++ source code. In such
+    cases, the first use contains the initialization (a cir.store, a cir.call
+    to a ctor, etc).
+
+    The presence of the `const` attribute indicates that the local variable is
+    declared with C/C++ `const` keyword.
+
+    The `dynAllocSize` specifies the size to dynamically allocate on the stack
----------------
erichkeane wrote:

Can we get a test of const and VLAs?  I didn't see one.

https://github.com/llvm/llvm-project/pull/128792