From 1e9163c73dab2c740d9673d97667ea4cd65cbdcc Mon Sep 17 00:00:00 2001
From: Alessandro Di Federico <ale@clearmind.me>
Date: Thu, 2 Mar 2017 11:16:32 +0100
Subject: [PATCH] Anticipate `cpu_loop_exit` removal

Fix of another bug showing up only with LLVM in debug mode: splitting a
malformed basic block is not allowed, and we had a function call after a
`ret` instruction.
---
 codegenerator.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/codegenerator.cpp b/codegenerator.cpp
index d9dcc7300..d31bf7baa 100644
--- a/codegenerator.cpp
+++ b/codegenerator.cpp
@@ -427,8 +427,13 @@ bool CpuLoopExitPass::runOnModule(llvm::Module& M) {
 
   assert(CpuLoop != nullptr);
 
-  for (User *TheUser : CpuLoopExit->users()) {
-    auto *Call = cast<CallInst>(TheUser);
+  std::queue<User *> CpuLoopExitUsers;
+  for (User *TheUser : CpuLoopExit->users())
+    CpuLoopExitUsers.push(TheUser);
+
+  while (!CpuLoopExitUsers.empty()) {
+    auto *Call = cast<CallInst>(CpuLoopExitUsers.front());
+    CpuLoopExitUsers.pop();
     assert(Call->getCalledFunction() == CpuLoopExit);
 
     // Call cpu_loop
@@ -444,9 +449,11 @@ bool CpuLoopExitPass::runOnModule(llvm::Module& M) {
     auto *Unreach = cast<UnreachableInst>(&*++Call->getIterator());
     Unreach->eraseFromParent();
 
-    // Remove the call to cpu_loop_exit
     Function *Caller = Call->getParent()->getParent();
 
+    // Remove the call to cpu_loop_exit
+    Call->eraseFromParent();
+
     if (FixedCallers.find(Caller) == FixedCallers.end()) {
       FixedCallers.insert(Caller);
 
@@ -518,9 +525,6 @@ bool CpuLoopExitPass::runOnModule(llvm::Module& M) {
     }
   }
 
-  for (User *TheUser : CpuLoopExit->users())
-    cast<Instruction>(TheUser)->eraseFromParent();
-
   return true;
 }