[llvm] [speculative-execution] Hoists debug values unnecessarily. (PR #85782)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -260,10 +260,31 @@ static InstructionCost ComputeSpeculationCost(const Instruction *I,
   }
 }
 
+// Do not hoist any debug info intrinsics.
+// ...
+// if (cond) {
+//   x = y * z;
+//   foo();
+// }
+// ...
+// -------- Which then becomes:
+// ...
+// if.then:
+//   %x = mul i32 %y, %z
+//   call void @llvm.dbg.value(%x, !"x", !DIExpression())
+//   call void foo()
+//
+// If SpeculativeExecution might decide to hoist the 'y * z' calculation
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OCHyams wrote:

nit: remove `If`?

https://github.com/llvm/llvm-project/pull/85782