From c44d71b8df9b00853c439d317563500b634068c1 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Tue, 27 Jan 2015 22:57:39 +0000
Subject: [PATCH] SymbolRewriter: allow rewriting with comdats

COMDATs must be identically named to the symbol.  When support for COMDATs was
introduced, the symbol rewriter was not updated, resulting in rewriting failing
for symbols which were placed into COMDATs.  This corrects the behaviour and
adds test cases for this.

llvm-svn: 227261
---
 llvm/lib/Transforms/Utils/SymbolRewriter.cpp | 20 ++++++++++++
 llvm/test/SymbolRewriter/rewrite.ll          | 33 ++++++++++++++++++++
 llvm/test/SymbolRewriter/rewrite.map         | 20 ++++++++++++
 3 files changed, 73 insertions(+)

diff --git a/llvm/lib/Transforms/Utils/SymbolRewriter.cpp b/llvm/lib/Transforms/Utils/SymbolRewriter.cpp
index c93cdc4b52e2..d36283ea3ae1 100644
--- a/llvm/lib/Transforms/Utils/SymbolRewriter.cpp
+++ b/llvm/lib/Transforms/Utils/SymbolRewriter.cpp
@@ -79,6 +79,19 @@ static cl::list<std::string> RewriteMapFiles("rewrite-map-file",
 
 namespace llvm {
 namespace SymbolRewriter {
+void rewriteComdat(Module &M, GlobalObject *GO, const std::string &Source,
+                   const std::string &Target) {
+  if (Comdat *CD = GO->getComdat()) {
+    auto &Comdats = M.getComdatSymbolTable();
+
+    Comdat *C = M.getOrInsertComdat(Target);
+    C->setSelectionKind(CD->getSelectionKind());
+    GO->setComdat(C);
+
+    Comdats.erase(Comdats.find(Source));
+  }
+}
+
 template <RewriteDescriptor::Type DT, typename ValueType,
           ValueType *(llvm::Module::*Get)(StringRef) const>
 class ExplicitRewriteDescriptor : public RewriteDescriptor {
@@ -102,10 +115,14 @@ template <RewriteDescriptor::Type DT, typename ValueType,
 bool ExplicitRewriteDescriptor<DT, ValueType, Get>::performOnModule(Module &M) {
   bool Changed = false;
   if (ValueType *S = (M.*Get)(Source)) {
+    if (GlobalObject *GO = dyn_cast<GlobalObject>(S))
+      rewriteComdat(M, GO, Source, Target);
+
     if (Value *T = (M.*Get)(Target))
       S->setValueName(T->getValueName());
     else
       S->setName(Target);
+
     Changed = true;
   }
   return Changed;
@@ -148,6 +165,9 @@ performOnModule(Module &M) {
     if (C.getName() == Name)
       continue;
 
+    if (GlobalObject *GO = dyn_cast<GlobalObject>(&C))
+      rewriteComdat(M, GO, C.getName(), Name);
+
     if (Value *V = (M.*Get)(Name))
       C.setValueName(V->getValueName());
     else
diff --git a/llvm/test/SymbolRewriter/rewrite.ll b/llvm/test/SymbolRewriter/rewrite.ll
index 716fff9f284c..e8a0db6d606c 100644
--- a/llvm/test/SymbolRewriter/rewrite.ll
+++ b/llvm/test/SymbolRewriter/rewrite.ll
@@ -28,12 +28,40 @@ entry:
   ret void
 }
 
+$source_comdat_function = comdat any
+define dllexport void @source_comdat_function() comdat($source_comdat_function) {
+entry:
+  ret void
+}
+
+$source_comdat_function_1 = comdat exactmatch
+define dllexport void @source_comdat_function_1() comdat($source_comdat_function_1) {
+entry:
+  ret void
+}
+
+$source_comdat_variable = comdat largest
+@source_comdat_variable = global i32 32, comdat($source_comdat_variable)
+
+$source_comdat_variable_1 = comdat noduplicates
+@source_comdat_variable_1 = global i32 64, comdat($source_comdat_variable_1)
+
+; CHECK: $target_comdat_function = comdat any
+; CHECK: $target_comdat_function_1 = comdat exactmatch
+; CHECK: $target_comdat_variable = comdat largest
+; CHECK: $target_comdat_variable_1 = comdat noduplicates
+
 ; CHECK: @target_variable = external global i32
 ; CHECK-NOT: @source_variable = external global i32
 ; CHECK: @target_pattern_variable = external global i32
 ; CHECK-NOT: @source_pattern_variable = external global i32
 ; CHECK: @target_pattern_multiple_variable_matches = external global i32
 ; CHECK-NOT: @source_pattern_multiple_variable_matches = external global i32
+; CHECK: @target_comdat_variable = global i32 32, comdat
+; CHECK-NOT: @source_comdat_variable = global i32 32, comdat
+; CHECK: @target_comdat_variable_1 = global i32 64, comdat
+; CHECK-NOT: @source_comdat_variable_1 = global i32 64, comdat
+
 ; CHECK: declare void @target_function()
 ; CHECK-NOT: declare void @source_function()
 ; CHECK: declare void @target_pattern_function()
@@ -57,3 +85,8 @@ entry:
 ; CHECK:   ret i32 %res
 ; CHECK: }
 
+; CHECK: define dllexport void @target_comdat_function() comdat
+; CHECK-NOT: define dllexport void @source_comdat_function() comdat
+; CHECK: define dllexport void @target_comdat_function_1() comdat
+; CHECK-NOT: define dllexport void @source_comdat_function_1() comdat
+
diff --git a/llvm/test/SymbolRewriter/rewrite.map b/llvm/test/SymbolRewriter/rewrite.map
index ef6dfc8ca2b9..8094939d088d 100644
--- a/llvm/test/SymbolRewriter/rewrite.map
+++ b/llvm/test/SymbolRewriter/rewrite.map
@@ -44,3 +44,23 @@ global alias: {
   target: _ZN1SD1Ev,
 }
 
+function: {
+  source: source_comdat_function,
+  target: target_comdat_function,
+}
+
+function: {
+  source: source_comdat_function_(.*),
+  transform: target_comdat_function_\1,
+}
+
+global variable: {
+  source: source_comdat_variable,
+  target: target_comdat_variable,
+}
+
+global variable: {
+  source: source_comdat_variable_(.*),
+  transform: target_comdat_variable_\1,
+}
+