[llvm] [GVN] Permit load PRE to happen in more cases (PR #76063)

[Nikita Popov via llvm-commits]

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@@ -282,3 +284,97 @@ header:
   call void @hold(i32 %v1)
   br label %header
 }
+
+
+; In block Z one load is unavailable (via entry block), whereas via other 2
+; predecessors the loads are available.
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nikic wrote:

As far as GVN knows, the load is not available in block B. If it were, the transform would already be performed.

https://github.com/llvm/llvm-project/pull/76063