C API: support scalable vectors

This adds support for scalable vector types in the C API and in
llvm-c-test, and also adds a test to ensure that llvm-c-test can properly
roundtrip operations involving scalable vectors.

While creating this diff, I discovered that the C API cannot properly roundtrip
_constant expressions_ involving shufflevector / scalable vectors, but that
seems to be a separate enough issue that I plan to address it in a future diff
(unless reviewers feel it should be addressed here).

Differential Revision: https://reviews.llvm.org/D89816

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/tools/llvm-c-test/echo.cpp b/llvm/tools/llvm-c-test/echo.cpp
index 0b3a10f..47dddd3 100644
--- a/llvm/tools/llvm-c-test/echo.cpp
+++ b/llvm/tools/llvm-c-test/echo.cpp
@@ -139,14 +139,14 @@ struct TypeCloner {
           Clone(LLVMGetElementType(Src)),
           LLVMGetPointerAddressSpace(Src)
         );
-      case LLVMScalableVectorTypeKind:
-        // FIXME: scalable vectors unsupported
-        break;
       case LLVMVectorTypeKind:
         return LLVMVectorType(
           Clone(LLVMGetElementType(Src)),
           LLVMGetVectorSize(Src)
         );
+      case LLVMScalableVectorTypeKind:
+        return LLVMScalableVectorType(Clone(LLVMGetElementType(Src)),
+                                      LLVMGetVectorSize(Src));
       case LLVMMetadataTypeKind:
         return LLVMMetadataTypeInContext(Ctx);
       case LLVMX86_MMXTypeKind: