[llvm] Account for inline assembly instructions in inlining cost. (PR #146628)

[David Li via llvm-commits]

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@@ -777,6 +786,42 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
 
     addCost(SwitchCost);
   }
+
+  // Parses the inline assembly argument to account for its cost. Inline
+  // assembly instructions incur higher costs for inlining since they cannot be
+  // analyzed and optimized.
+  void onInlineAsm(InlineAsm &Arg) override {
+    SmallVector<StringRef, 4> Fragments;
+    Arg.getAsmString().split(Fragments, "\n");
+    int SectionLevel = 0;
+    int InlineAsmInstrCount = 0;
+    for (const auto &Fragment : Fragments) {
+      // Trim whitespaces and comments.
+      auto Trimmed = Fragment.trim();
+      size_t hashPos = Trimmed.find('#');
+      if (hashPos != StringRef::npos)
+        Trimmed = Trimmed.substr(0, hashPos);
+      // Ignore comments.
+      if (Trimmed.empty())
+        continue;
+      if (Trimmed.starts_with(".pushsection")) {
+        ++SectionLevel;
+        continue;
+      }
+      if (Trimmed.starts_with(".popsection")) {
+        --SectionLevel;
+        continue;
+      }
+      // Ignore directives and labels.
+      if (Trimmed.starts_with(".") || Trimmed.contains(":"))
+        continue;
+      if (SectionLevel == 0)
+        ++InlineAsmInstrCount;
----------------
david-xl wrote:

Why treating all instructions in user section as one instruction?

https://github.com/llvm/llvm-project/pull/146628