From f9fb9da36c34d2745b74dc30e6c26f7d3f48466c Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas@devlieghere.com>
Date: Wed, 14 Oct 2020 20:10:55 -0700
Subject: [PATCH] [dsymutil] Fix handling of aliases to private external
 symbols

dsymutil was incorrectly ignoring aliases to private extern symbols in
the MachODebugMapParser. This resulted in spurious warnings about not
being able to find symbols.

rdar://49652389

Differential revision: https://reviews.llvm.org/D89444
---
 .../tools/dsymutil/ARM/private-extern-alias.test   |  29 +++++++++++++++++++++
 .../Inputs/private/tmp/private_extern/main.o       | Bin 0 -> 1904 bytes
 .../private/tmp/private_extern/private_extern.o    | Bin 0 -> 2160 bytes
 .../private/tmp/private_extern/private_extern.out  | Bin 0 -> 33536 bytes
 llvm/tools/dsymutil/MachODebugMapParser.cpp        |   4 ++-
 5 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/tools/dsymutil/ARM/private-extern-alias.test
 create mode 100644 llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/main.o
 create mode 100644 llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.o
 create mode 100755 llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.out

diff --git a/llvm/test/tools/dsymutil/ARM/private-extern-alias.test b/llvm/test/tools/dsymutil/ARM/private-extern-alias.test
new file mode 100644
index 0000000..99301fe
--- /dev/null
+++ b/llvm/test/tools/dsymutil/ARM/private-extern-alias.test
@@ -0,0 +1,29 @@
+$ cat private_extern.c
+__attribute__((visibility("hidden")))
+int* foo() {
+  int i = 10;
+  volatile int* j = &i;
+  return j;
+}
+
+int* bar() {
+  return foo();
+}
+
+$ cat main.c
+int* bar();
+int main() {
+  return *bar();
+}
+
+$ cat alias_list
+_foo _baz
+
+$ xcrun --sdk iphoneos clang -g private_extern.c -c -o private_extern.o -target arm64-apple-ios14.0
+$ xcrun --sdk iphoneos clang -g main.c -c -o main.o -target arm64-apple-ios14.0
+$ xcrun --sdk iphoneos clang private_extern.o main.o -target arm64-apple-ios14.0 -o private_extern.out -Xlinker -alias_list -Xlinker alias_list
+
+RUN: dsymutil -oso-prepend-path %p/../Inputs %p/../Inputs/private/tmp/private_extern/private_extern.out -o %t.dSYM --verbose 2>&1 | FileCheck %s
+CHECK-NOT: could not find object file symbol for symbol _baz
+CHECK: { sym: _foo, objAddr: 0x0000000000000000, binAddr: 0x0000000100007F58, size: 0x00000020 }
+CHECK: { sym: _baz, objAddr: 0x0000000000000000, binAddr: 0x0000000100007F58, size: 0x00000000 }
diff --git a/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/main.o b/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/main.o
new file mode 100644
index 0000000000000000000000000000000000000000..d9cf74ee64403d5f7049e7b6038f52715d78a55d
GIT binary patch
literal 1904
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literal 0
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diff --git a/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.o b/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.o
new file mode 100644
index 0000000000000000000000000000000000000000..b7f1a6a8e8472cb517572cea3a73dd37af650148
GIT binary patch
literal 2160
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literal 0
HcmV?d00001

diff --git a/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.out b/llvm/test/tools/dsymutil/Inputs/private/tmp/private_extern/private_extern.out
new file mode 100755
index 0000000000000000000000000000000000000000..fff5df162cf752aba4eb9361c0b9d6893e1d40da
GIT binary patch
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literal 0
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diff --git a/llvm/tools/dsymutil/MachODebugMapParser.cpp b/llvm/tools/dsymutil/MachODebugMapParser.cpp
index 617b708..3323a05 100644
--- a/llvm/tools/dsymutil/MachODebugMapParser.cpp
+++ b/llvm/tools/dsymutil/MachODebugMapParser.cpp
@@ -562,7 +562,9 @@ void MachODebugMapParser::loadMainBinarySymbols(
       continue;
     }
     Section = *SectionOrErr;
-    if (Section == MainBinary.section_end() || Section->isText())
+    if ((Section == MainBinary.section_end() || Section->isText()) &&
+        !(SymType &
+          MachO::N_PEXT)) // Alias to non-external (was a private external)
       continue;
     uint64_t Addr = cantFail(Sym.getValue());
     Expected<StringRef> NameOrErr = Sym.getName();
-- 
2.7.4