[compiler-rt] [llvm] [PGO] Add option to always instrumenting loop entries (PR #116789)

[Christian Ulmann via llvm-commits]

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@@ -742,9 +744,10 @@ serializeValueProfDataFrom(ValueProfRecordClosure *Closure,
  */
 #define VARIANT_MASKS_ALL 0xffffffff00000000ULL
 #define GET_VERSION(V) ((V) & ~VARIANT_MASKS_ALL)
-#define VARIANT_MASK_IR_PROF (0x1ULL << 56)
-#define VARIANT_MASK_CSIR_PROF (0x1ULL << 57)
-#define VARIANT_MASK_INSTR_ENTRY (0x1ULL << 58)
+#define VARIANT_MASK_IR_PROF (0x1ULL << 55)
+#define VARIANT_MASK_CSIR_PROF (0x1ULL << 56)
+#define VARIANT_MASK_INSTR_ENTRY (0x1ULL << 57)
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Dinistro wrote:

Considering that there is no usage of bit `55` and that there is no documentation about this being reserved, I would argue that we should be free to use `55`. If any downstream user is relying on such an undocumented implementation detail, we should be free to break it. 

https://github.com/llvm/llvm-project/pull/116789