[llvm] [PseudoProbe] Extend to skip instrumenting probe into the dests of invoke (PR #79919)

[via llvm-commits]

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@@ -173,21 +173,108 @@ SampleProfileProber::SampleProfileProber(Function &Func,
   BlockProbeIds.clear();
   CallProbeIds.clear();
   LastProbeId = (uint32_t)PseudoProbeReservedId::Last;
-  computeProbeIdForBlocks();
-  computeProbeIdForCallsites();
-  computeCFGHash();
+
+  DenseSet<BasicBlock *> BlocksToIgnore;
+  DenseSet<BasicBlock *> BlocksAndCallsToIgnore;
+  computeBlocksToIgnore(BlocksToIgnore, BlocksAndCallsToIgnore);
+
+  computeProbeIdForBlocks(BlocksToIgnore);
+  computeProbeIdForCallsites(BlocksAndCallsToIgnore);
+  computeCFGHash(BlocksToIgnore);
+}
+
+// Two purposes to compute the blocks to ignore:
+// 1. Reduce the IR size.
+// 2. Make the instrumentation(checksum) stable. e.g. the frondend may
+// generate unstable IR while optimizing nounwind attribute, some versions are
+// optimized with the call-to-invoke conversion, while other versions do not.
+// This discrepancy in probe ID could cause profile mismatching issues.
+// Note that those ignored blocks are either cold blocks or new split blocks
+// whose original blocks are instrumented, so it shouldn't degrade the profile
+// quailty.
+void SampleProfileProber::computeBlocksToIgnore(
+    DenseSet<BasicBlock *> &BlocksToIgnore,
+    DenseSet<BasicBlock *> &BlocksAndCallsToIgnore) {
+  // Ignore the cold EH and unreachable blocks and calls.
+  computeEHOnlyBlocks(*F, BlocksAndCallsToIgnore);
+  findUnreachableBlocks(BlocksAndCallsToIgnore);
+
+  BlocksToIgnore.insert(BlocksAndCallsToIgnore.begin(),
+                        BlocksAndCallsToIgnore.end());
+  // Handle the call-to-invoke conversion case, ignore the normal dests of
+  // invoke.
+  findInvokeNormalDests(BlocksToIgnore);
+}
+
+void SampleProfileProber::findUnreachableBlocks(
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WenleiHe wrote:

Also add a comment explain why unreachable blocks are ignored

https://github.com/llvm/llvm-project/pull/79919