[flang-commits] [flang] [llvm] [flang-rt] - Lightweight runtime assignment function (AssignSimple) for intrinsic-type assignments (PR #213704)

[Tom Eccles via flang-commits]

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@@ -851,6 +852,218 @@ void RTDEF(AssignExplicitLengthCharacter)(Descriptor &to,
           ExplicitLengthCharacterLHS);
 }
 
+void RTDEF(AssignSimple)(Descriptor &to, const Descriptor &from,
+    const char *sourceFile, int sourceLine) {
+  Terminator terminator{sourceFile, sourceLine};
+  // AssignSimple: fast path for intrinsic type assignments (integer, real,
+  // complex, logical). The compiler routes here only when:
+  //   - LHS element type is trivial (isa_trivial), not derived/polymorphic
+  //   - LHS and RHS ranks match (no scalar-to-array broadcasting)
+  //   - LHS is not volatile (volatile needs memory ordering semantics)
+
+  if (to.rank() != from.rank()) {
+    terminator.Crash("AssignSimple: rank mismatch (to.rank=%d, from.rank=%d)",
+        to.rank(), from.rank());
+  }
+  if (to.ElementBytes() != from.ElementBytes()) {
+    terminator.Crash("AssignSimple: ElementBytes mismatch (to.ElementBytes=%d, "
+                     "from.ElementBytes=%d)",
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tblah wrote:

Is %d safe for ElementBytes()?

https://github.com/llvm/llvm-project/pull/213704