From 081c215cca971b6b6d7988e9f48e4793ceb374dc Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 12 Nov 2013 04:53:19 +0000
Subject: [PATCH] Keep the old function order in
 CodeGenModule::applyReplacements.

The original decls are created when used. The replacements are created at the
end of the TU in reverse order.

This makes the original order far better for testing. This is particularly
important since the replacement logic could be used even when
-mconstructor-aliases is not used, but that would make many tests hard to read.

This is a fixed version of r194357 which handles replacing a destructor with
another which is an alias to a third one.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194452 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CodeGenModule.cpp   | 18 ++++++++++++++++--
 test/CodeGenCXX/destructors.cpp | 16 ++++++++--------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 74f3bbb045..1f2f4bbde3 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -181,8 +181,22 @@ void CodeGenModule::applyReplacements() {
     llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
     if (!Entry)
       continue;
-    Entry->replaceAllUsesWith(Replacement);
-    Entry->eraseFromParent();
+    llvm::Function *OldF = cast<llvm::Function>(Entry);
+    llvm::Function *NewF = dyn_cast<llvm::Function>(Replacement);
+    if (!NewF) {
+      llvm::ConstantExpr *CE = cast<llvm::ConstantExpr>(Replacement);
+      assert(CE->getOpcode() == llvm::Instruction::BitCast ||
+             CE->getOpcode() == llvm::Instruction::GetElementPtr);
+      NewF = dyn_cast<llvm::Function>(CE->getOperand(0));
+    }
+
+    // Replace old with new, but keep the old order.
+    OldF->replaceAllUsesWith(Replacement);
+    if (NewF) {
+      NewF->removeFromParent();
+      OldF->getParent()->getFunctionList().insertAfter(OldF, NewF);
+    }
+    OldF->eraseFromParent();
   }
 }
 
diff --git a/test/CodeGenCXX/destructors.cpp b/test/CodeGenCXX/destructors.cpp
index 5b29ce5de4..59c97b7dca 100644
--- a/test/CodeGenCXX/destructors.cpp
+++ b/test/CodeGenCXX/destructors.cpp
@@ -36,13 +36,13 @@ namespace PR7526 {
 
   struct allocator_derived : allocator { };
 
+  // CHECK-LABEL: define void @_ZN6PR75263fooEv()
+  // CHECK: call void {{.*}} @_ZN6PR75269allocatorD2Ev
+
   // CHECK-LABEL: define void @_ZN6PR75269allocatorD2Ev(%"struct.PR7526::allocator"* %this) unnamed_addr
   // CHECK: call void @__cxa_call_unexpected
   allocator::~allocator() throw() { foo(); }
 
-  // CHECK-LABEL: define void @_ZN6PR75263fooEv()
-  // CHECK: call void {{.*}} @_ZN6PR75269allocatorD2Ev
-
   void foo() {
     allocator_derived ad;
   }
@@ -393,16 +393,16 @@ namespace test10 {
   // CHECK: call void @_ZN5test312_GLOBAL__N_11DD0Ev(
   // CHECK: ret void
 
-  // CHECK-LABEL: define internal void @_ZN5test312_GLOBAL__N_11CD2Ev(%"struct.test3::<anonymous namespace>::C"* %this) unnamed_addr
-  // CHECK: invoke void @_ZN5test31BD2Ev(
-  // CHECK: call void @_ZN5test31AD2Ev(
-  // CHECK: ret void
-
   // CHECK-LABEL: define internal void @_ZThn8_N5test312_GLOBAL__N_11CD1Ev(
   // CHECK: getelementptr inbounds i8* {{.*}}, i64 -8
   // CHECK: call void @_ZN5test312_GLOBAL__N_11CD2Ev(
   // CHECK: ret void
 
+  // CHECK-LABEL: define internal void @_ZN5test312_GLOBAL__N_11CD2Ev(%"struct.test3::<anonymous namespace>::C"* %this) unnamed_addr
+  // CHECK: invoke void @_ZN5test31BD2Ev(
+  // CHECK: call void @_ZN5test31AD2Ev(
+  // CHECK: ret void
+
   // CHECK: declare void @_ZN5test31BD2Ev(
   // CHECK: declare void @_ZN5test31AD2Ev(
 
-- 
2.40.0