From 22d5bd0e3b32530785bc7b5c0f32b32a1f907342 Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl@apple.com>
Date: Wed, 18 Mar 2020 15:30:20 -0700
Subject: [PATCH] Allow remapping Clang module include paths

in the debug info with -fdebug-prefix-map.

rdar://problem/55685132

This reapplies an earlier attempt to commit this without
modifications.

Differential Revision: https://reviews.llvm.org/D76385
---
 clang/lib/CodeGen/CGDebugInfo.cpp            | 30 +++++++++++++-------
 clang/test/Modules/debug-info-moduleimport.m |  2 ++
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index da6cb458982b..49c57e9860a6 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2483,6 +2483,17 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
     assert(StringRef(M->Name).startswith(CGM.getLangOpts().ModuleName) &&
            "clang module without ASTFile must be specified by -fmodule-name");
 
+  // Return a StringRef to the remapped Path.
+  auto RemapPath = [this](StringRef Path) -> std::string {
+    std::string Remapped = remapDIPath(Path);
+    StringRef Relative(Remapped);
+    StringRef CompDir = TheCU->getDirectory();
+    if (Relative.consume_front(CompDir))
+      Relative.consume_front(llvm::sys::path::get_separator());
+
+    return Relative.str();
+  };
+
   if (CreateSkeletonCU && IsRootModule && !Mod.getASTFile().empty()) {
     // PCH files don't have a signature field in the control block,
     // but LLVM detects skeleton CUs by looking for a non-zero DWO id.
@@ -2496,16 +2507,12 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
     if (!llvm::sys::path::is_absolute(Mod.getASTFile()))
       PCM = Mod.getPath();
     llvm::sys::path::append(PCM, Mod.getASTFile());
-    std::string RemappedPCM = remapDIPath(PCM);
-    StringRef RelativePCM(RemappedPCM);
-    StringRef CompDir = TheCU->getDirectory();
-    if (RelativePCM.consume_front(CompDir))
-      RelativePCM.consume_front(llvm::sys::path::get_separator());
-    DIB.createCompileUnit(TheCU->getSourceLanguage(),
-                          // TODO: Support "Source" from external AST providers?
-                          DIB.createFile(Mod.getModuleName(), CompDir),
-                          TheCU->getProducer(), false, StringRef(), 0, RelativePCM,
-                          llvm::DICompileUnit::FullDebug, Signature);
+    DIB.createCompileUnit(
+        TheCU->getSourceLanguage(),
+        // TODO: Support "Source" from external AST providers?
+        DIB.createFile(Mod.getModuleName(), TheCU->getDirectory()),
+        TheCU->getProducer(), false, StringRef(), 0, RemapPath(PCM),
+        llvm::DICompileUnit::FullDebug, Signature);
     DIB.finalize();
   }
 
@@ -2513,9 +2520,10 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
       IsRootModule ? nullptr
                    : getOrCreateModuleRef(ASTSourceDescriptor(*M->Parent),
                                           CreateSkeletonCU);
+  std::string IncludePath = Mod.getPath().str();
   llvm::DIModule *DIMod =
       DBuilder.createModule(Parent, Mod.getModuleName(), ConfigMacros,
-                            Mod.getPath());
+                            RemapPath(IncludePath));
   ModuleCache[M].reset(DIMod);
   return DIMod;
 }
diff --git a/clang/test/Modules/debug-info-moduleimport.m b/clang/test/Modules/debug-info-moduleimport.m
index 9dee9964b538..5787ffe22751 100644
--- a/clang/test/Modules/debug-info-moduleimport.m
+++ b/clang/test/Modules/debug-info-moduleimport.m
@@ -34,9 +34,11 @@
 
 // RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps \
 // RUN:   -fmodules-cache-path=%t -fdebug-prefix-map=%t=/MODULE-CACHE \
+// RUN:   -fdebug-prefix-map=%S=/SRCDIR \
 // RUN:   -fmodule-format=obj -dwarf-ext-refs \
 // RUN:   %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
 // RUN:     | FileCheck %s --check-prefix=SKEL-CHECK
+// SKEL-CHECK: includePath: "/SRCDIR/Inputs"
 // SKEL-CHECK: distinct !DICompileUnit({{.*}}file: ![[CUFILE:[0-9]+]]
 // SKEL-CHECK: ![[CUFILE]] = !DIFile({{.*}}directory: "[[COMP_DIR:.*]]"
 // SKEL-CHECK: distinct !DICompileUnit({{.*}}file: ![[DWOFILE:[0-9]+]]{{.*}}splitDebugFilename: "/MODULE-CACHE{{.*}}dwoId