[llvm] [SampleProfile] Fix bug where intentionally constructed function with empty name asserts. (PR #71479)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: William Junda Huang (huangjd)

<details>
<summary>Changes</summary>

Normally SampleContext does not allow using an empty StirngRef to construct an object, this is to prevent bugs reading the profile. However empty names may be emitted by a function which its name is intentionally set to empty, or a bug in the remapper (which should be investigated separately) that remaps a non-empty name to an empty string. Regardless, converting it to FunctionId first will prevent the assert, and that assert check is unnecessary, which will be addressed in another patch

---
Full diff: https://github.com/llvm/llvm-project/pull/71479.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/IPO/SampleProfile.cpp (+3-3) 


``````````diff
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index a7773737ef16bd3..063f7b42022ff83 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1630,7 +1630,7 @@ void SampleProfileLoader::promoteMergeNotInlinedContextSamples(
         // separate map so that it does not rehash the original profile.
         if (!OutlineFS)
           OutlineFS = &OutlineFunctionSamples[
-              FunctionSamples::getCanonicalFnName(Callee->getName())];
+              FunctionId(FunctionSamples::getCanonicalFnName(Callee->getName()))];
         OutlineFS->merge(*FS, 1);
         // Set outlined profile to be synthetic to not bias the inliner.
         OutlineFS->SetContextSynthetic();
@@ -2675,12 +2675,12 @@ bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM)
     // into base.
     if (!Samples) {
       StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
-      auto It = OutlineFunctionSamples.find(CanonName);
+      auto It = OutlineFunctionSamples.find(FunctionId(CanonName));
       if (It != OutlineFunctionSamples.end()) {
         Samples = &It->second;
       } else if (auto Remapper = Reader->getRemapper()) {
         if (auto RemppedName = Remapper->lookUpNameInProfile(CanonName)) {
-          It = OutlineFunctionSamples.find(*RemppedName);
+          It = OutlineFunctionSamples.find(FunctionId(*RemppedName));
           if (It != OutlineFunctionSamples.end())
             Samples = &It->second;
         }

``````````

</details>


https://github.com/llvm/llvm-project/pull/71479