[llvm] [memprof] Compute CallStackId when deserializing IndexedAllocationInfo (PR #86421)

[Snehasish Kumar via llvm-commits]

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@@ -1261,6 +1261,14 @@ Error IndexedInstrProfReader::readHeader() {
         /*Buckets=*/Start + FrameTableOffset,
         /*Payload=*/Start + FramePayloadOffset,
         /*Base=*/Start, memprof::FrameLookupTrait()));
+
+#if EXPENSIVE_CHECKS
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snehasish wrote:

nit: I think the convention is to use `#ifdef` which is slightly different in meaning to `#if` only.

https://github.com/llvm/llvm-project/pull/86421