From: David Chisnall <csdavec@swan.ac.uk>
Date: Sun, 31 Mar 2019 11:22:26 +0000 (+0000)
Subject: COMDAT-fold block descriptors.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=94c9e98ba7184779aba9b994724be2a7b7335909;p=clang

COMDAT-fold block descriptors.

Without this change, linking multiple objects containing block
descriptors together on Windows will generate duplicate symbol errors.

Patch by Dustin Howett!

Differential Revision: https://reviews.llvm.org/D58807

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@357363 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index 1c10c46baa..731735841e 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -274,6 +274,8 @@ static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
                                      /*constant*/ true, linkage, AddrSpace);
 
   if (linkage == llvm::GlobalValue::LinkOnceODRLinkage) {
+    if (CGM.supportsCOMDAT())
+      global->setComdat(CGM.getModule().getOrInsertComdat(descName));
     global->setVisibility(llvm::GlobalValue::HiddenVisibility);
     global->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
   }
diff --git a/test/CodeGenObjC/block-desc-str.m b/test/CodeGenObjC/block-desc-str.m
index 44d2f21433..890a214ae6 100644
--- a/test/CodeGenObjC/block-desc-str.m
+++ b/test/CodeGenObjC/block-desc-str.m
@@ -1,9 +1,13 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-freebsd -emit-llvm -fobjc-runtime=gnustep-1.7 -fblocks -o - %s | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -emit-llvm -fobjc-runtime=gcc -fblocks -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-unknown-freebsd -emit-llvm -fobjc-runtime=gnustep-1.7 -fblocks -o - %s | FileCheck --check-prefix=CHECK-COMDAT %s
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -emit-llvm -fobjc-runtime=gcc -fblocks -o - %s | FileCheck --check-prefix=CHECK-COMDAT %s
 // RUN: %clang_cc1 -triple=x86_64-apple-darwin10 -emit-llvm -fblocks -o - %s | FileCheck %s
 
 // Test that descriptor symbol names don't include '@'.
 
+// CHECK-COMDAT: $"__block_descriptor_40_8_32o_e5_v8\01?0l" = comdat any
+// CHECK-COMDAT: @[[STR:.*]] = private unnamed_addr constant [6 x i8] c"v8@?0\00"
+// CHECK-COMDAT: @"__block_descriptor_40_8_32o_e5_v8\01?0l" = linkonce_odr hidden unnamed_addr constant { i64, i64, i8*, i8*, i8*, {{.*}} } { i64 0, i64 40, i8* bitcast ({{.*}} to i8*), i8* bitcast ({{.*}} to i8*), i8* getelementptr inbounds ([6 x i8], [6 x i8]* @[[STR]], i32 0, i32 0), {{.*}} }, comdat, align 8
+
 // CHECK: @[[STR:.*]] = private unnamed_addr constant [6 x i8] c"v8@?0\00"
 // CHECK: @"__block_descriptor_40_8_32o_e5_v8\01?0l" = linkonce_odr hidden unnamed_addr constant { i64, i64, i8*, i8*, i8*, {{.*}} } { i64 0, i64 40, i8* bitcast ({{.*}} to i8*), i8* bitcast ({{.*}} to i8*), i8* getelementptr inbounds ([6 x i8], [6 x i8]* @[[STR]], i32 0, i32 0), {{.*}} }, align 8