[llvm] [LV] Return Invalid from getLegacyCost when instruction cost forced. (PR #154543)

[Florian Hahn via llvm-commits]

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@@ -0,0 +1,24 @@
+; REQUIRES: asserts
+; RUN: opt < %s -passes=loop-vectorize -force-target-instruction-cost=1 -debug-only=loop-vectorize -S -disable-output 2>&1 | FileCheck %s
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fhahn wrote:

Can you move the test to `llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll`, which aloready has similar tests

https://github.com/llvm/llvm-project/pull/154543