From c3b1d730d69fbb66e521a3abe1c56053ae4f94e2 Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Fri, 14 Jun 2019 21:02:04 +0000
Subject: [PATCH] [COFF] Handle .eh_frame$symbol as associative comdat for
 MinGW

This matches how it is done for .xdata and .pdata already.

On i386, the symbol name in the section name suffix does not contain
the extra underscore prefix.

This is one part of a fix for PR42217.

Differential Revision: https://reviews.llvm.org/D63350

llvm-svn: 363456
---
 lld/COFF/InputFiles.cpp                       |  9 +++--
 lld/test/COFF/associative-comdat-mingw-i386.s | 37 +++++++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 lld/test/COFF/associative-comdat-mingw-i386.s

diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index 538a36e9508f..ebf6e4418439 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -288,6 +288,8 @@ void ObjFile::recordPrevailingSymbolForMingw(
   if (SC && SC->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE) {
     StringRef Name;
     COFFObj->getSymbolName(Sym, Name);
+    if (getMachineType() == I386)
+      Name.consume_front("_");
     PrevailingSectionMap[Name] = SectionNumber;
   }
 }
@@ -297,9 +299,10 @@ void ObjFile::maybeAssociateSEHForMingw(
     const DenseMap<StringRef, uint32_t> &PrevailingSectionMap) {
   StringRef Name;
   COFFObj->getSymbolName(Sym, Name);
-  if (Name.consume_front(".pdata$") || Name.consume_front(".xdata$")) {
-    // For MinGW, treat .[px]data$<func> as implicitly associative to
-    // the symbol <func>.
+  if (Name.consume_front(".pdata$") || Name.consume_front(".xdata$") ||
+      Name.consume_front(".eh_frame$")) {
+    // For MinGW, treat .[px]data$<func> and .eh_frame$<func> as implicitly
+    // associative to the symbol <func>.
     auto ParentSym = PrevailingSectionMap.find(Name);
     if (ParentSym != PrevailingSectionMap.end())
       readAssociativeDefinition(Sym, Def, ParentSym->second);
diff --git a/lld/test/COFF/associative-comdat-mingw-i386.s b/lld/test/COFF/associative-comdat-mingw-i386.s
new file mode 100644
index 000000000000..3f5e02330d50
--- /dev/null
+++ b/lld/test/COFF/associative-comdat-mingw-i386.s
@@ -0,0 +1,37 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -triple=i686-windows-gnu %s -filetype=obj -o %t.obj
+
+# RUN: lld-link -lldmingw -entry:main %t.obj -out:%t.exe
+# RUN: llvm-objdump -s %t.exe | FileCheck %s
+
+# Check that the .eh_frame comdat was included, even if it had no symbols,
+# due to associativity with the symbol _foo.
+
+# CHECK: Contents of section .eh_fram:
+# CHECK:  403000 42
+
+        .text
+        .def            _main;
+        .scl            2;
+        .type           32;
+        .endef
+        .globl          _main
+        .p2align        4, 0x90
+_main:
+        call            _foo
+        ret
+
+        .section        .eh_frame$foo,"dr"
+        .linkonce       discard
+        .byte           0x42
+
+        .def            _foo;
+        .scl            2;
+        .type           32;
+        .endef
+        .section        .text$foo,"xr",discard,foo
+        .globl          _foo
+        .p2align        4
+_foo:
+        ret