[clang] [clang][DebugInfo] Attach `DISubprogram` to additional call variants (PR #166202)

[Orlando Cazalet-Hyams via cfe-commits]

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@@ -6277,6 +6277,21 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
     pushDestroy(QualType::DK_nontrivial_c_struct, Ret.getAggregateAddress(),
                 RetTy);
 
+  if (CalleeDecl) {
+    // Generate function declaration DISuprogram in order to be used
+    // in debug info about call sites.
+    if (CGDebugInfo *DI = getDebugInfo()) {
+      CodeGenFunction CalleeCGF(CGM);
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OCHyams wrote:

Hmm that is not nothing, while I'm inclined to agree that the previous behaviour was unintended (and you're essentially fixing a bug/mistake) I also think that the status quo has carries weight.

The instructions:u regression at O0 is more significant than that thought, it's 0.03-0.34%. I wonder if there's something we can do about that? I believe we don't emit call site information for O0 builds anyway, so that extra cost is potentially redundant?

https://github.com/llvm/llvm-project/pull/166202