[llvm] [PseudoProbe] Use probe id as the base dwarf discriminator for callsites (PR #65685)

[via llvm-commits]

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@@ -2075,6 +2076,11 @@ class DILocation : public MDNode {
   static unsigned
   getBaseDiscriminatorFromDiscriminator(unsigned D,
                                         bool IsFSDiscriminator = false) {
+    // Return the probe id instead of zero for a pseudo probe discriminator.
+    // This should help differenciate callsites with same line numbers.
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WenleiHe wrote:

Suggest to make it clear that this is so we can still generate good quality AutoFDO profile when -fpseudo-probe-for-profiling is on, in which case we will use probe-id for calls as AutoFDO's discriminator for calls locations to avoid losing all discriminators for callsites. 

https://github.com/llvm/llvm-project/pull/65685