Update clambcc/clambc-compiler.py

Cisco-Talos · Aug 5, 2024 · 24d4c64 · 24d4c64
1 parent f7f2d81
commit 24d4c64
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/clambcc/clambc-compiler.py b/clambcc/clambc-compiler.py
@@ -599,7 +599,11 @@ def createInputSourceFile(clangLLVM: ClangLLVM, name: str, args: list, options:
     'verify',
 
     # Perform lowering pass.
-    # TODO: What do this do?
+    # In practice, this lowering pass changes index sizes from 64bit to 32bit in `GetElementPtr` instructions.
+    # There are some other lowering pass cases that are not run, either with our current signature set or because of prior passes. 
+    # For example, one of them lowers all `PtrToInt` instructions to point have a type of `i8`. 
+    # However, `PtrToIntInst` is not allowed, so this code never executes.
+    # It's possible some of these lowering pass cases were works-in-progress that were solved another way.
     'clambc-lowering-notfinal',
     'verify',