PPCAnalyst: Update comments

Source/Core/Core/PowerPC/PPCAnalyst.cpp

@@ -723,6 +723,11 @@ u32 PPCAnalyzer::Analyze(u32 address, CodeBlock* block, CodeBuffer* buffer, u32
                (inst.BO & BO_DONT_DECREMENT_FLAG) && (inst.BO & BO_DONT_CHECK_CONDITION))
       {
         // bclrx with unconditional branch = return
+        // Follow it if we can propagate the LR value of the last CALL instruction.
+        // Through it would be easy to track the upper level of call/return,
+        // we can't guarantee the LR value. The PPC ABI forces all functions to push
+        // the LR value on the stack as there are no spare registers. So we'd need
+        // to check all store instruction to not alias with the stack.
         follow = true;
         destination = code[caller].address + 4;
         found_call = false;

Source/Core/Core/PowerPC/PPCAnalyst.h

@@ -190,7 +190,8 @@ public:
     // Requires JIT support to be enabled.
     OPTION_CONDITIONAL_CONTINUE = (1 << 0),
 
-    // Try to inline unconditional branches.
+    // Try to inline unconditional branches/calls/returns.
+    // Also track the LR value to follow unconditional return instructions.
     // Might require JIT intervention to support it correctly.
     // Especially if the BLR optimization is used.
     OPTION_BRANCH_FOLLOW = (1 << 1),