Revert "[OPENMP] Fix PR38026: Link -latomic when -fopenmp is used."

This reverts commit r336467: libatomic is not available on all Linux
systems and this commit completely breaks OpenMP on them, even if there
are no atomic operations or all of them can be lowered to hardware
instructions.

See http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180716/234816.html
for post-commit discussion.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@337722 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
index ee3096813ed3c1bbdeadd012114fce142f7baccb..1ecf127c4b9cabfaecfe0317c22aeeada68a2f5a 100644 (file)
--- a/lib/Driver/ToolChains/Gnu.cpp
+++ b/lib/Driver/ToolChains/Gnu.cpp
@@ -479,7 +479,6 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
       bool WantPthread = Args.hasArg(options::OPT_pthread) ||
                          Args.hasArg(options::OPT_pthreads);
-      bool WantAtomic = false;
 
       // FIXME: Only pass GompNeedsRT = true for platforms with libgomp that
       // require librt. Most modern Linux platforms do, but some may not.
@@ -488,16 +487,13 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                            /* GompNeedsRT= */ true))
         // OpenMP runtimes implies pthreads when using the GNU toolchain.
         // FIXME: Does this really make sense for all GNU toolchains?
-        WantAtomic = WantPthread = true;
+        WantPthread = true;
 
       AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
       if (WantPthread && !isAndroid)
         CmdArgs.push_back("-lpthread");
 
-      if (WantAtomic)
-        CmdArgs.push_back("-latomic");
-
       if (Args.hasArg(options::OPT_fsplit_stack))
         CmdArgs.push_back("--wrap=pthread_create");
 

diff --git a/test/OpenMP/linking.c b/test/OpenMP/linking.c
index e2f83f9571ef1bc373fe78bee6c4a75eec1cffb5..802553c1be7525de7aeb8c5253a125a7f9e85f1d 100644 (file)
--- a/test/OpenMP/linking.c
+++ b/test/OpenMP/linking.c
@@ -8,14 +8,14 @@
 // RUN:   | FileCheck --check-prefix=CHECK-LD-32 %s
 // CHECK-LD-32: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-32: "-l[[DEFAULT_OPENMP_LIB:[^"]*]]"
-// CHECK-LD-32: "-lpthread" "-latomic" "-lc"
+// CHECK-LD-32: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -target x86_64-unknown-linux -rtlib=platform \
 // RUN:   | FileCheck --check-prefix=CHECK-LD-64 %s
 // CHECK-LD-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-64: "-l[[DEFAULT_OPENMP_LIB:[^"]*]]"
-// CHECK-LD-64: "-lpthread" "-latomic" "-lc"
+// CHECK-LD-64: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp=libgomp -target i386-unknown-linux -rtlib=platform \
@@ -27,7 +27,7 @@
 // SIMD-ONLY2-NOT: liomp
 // CHECK-GOMP-LD-32: "{{.*}}ld{{(.exe)?}}"
 // CHECK-GOMP-LD-32: "-lgomp" "-lrt"
-// CHECK-GOMP-LD-32: "-lpthread" "-latomic" "-lc"
+// CHECK-GOMP-LD-32: "-lpthread" "-lc"
 
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 -fopenmp-simd -target i386-unknown-linux -rtlib=platform | FileCheck --check-prefix SIMD-ONLY2 %s
 // SIMD-ONLY2-NOT: lgomp
@@ -39,21 +39,21 @@
 // RUN:   | FileCheck --check-prefix=CHECK-GOMP-LD-64 %s
 // CHECK-GOMP-LD-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-GOMP-LD-64: "-lgomp" "-lrt"
-// CHECK-GOMP-LD-64: "-lpthread" "-latomic" "-lc"
+// CHECK-GOMP-LD-64: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -target i386-unknown-linux -rtlib=platform \
 // RUN:   | FileCheck --check-prefix=CHECK-IOMP5-LD-32 %s
 // CHECK-IOMP5-LD-32: "{{.*}}ld{{(.exe)?}}"
 // CHECK-IOMP5-LD-32: "-l[[DEFAULT_OPENMP_LIB:[^"]*]]"
-// CHECK-IOMP5-LD-32: "-lpthread" "-latomic" "-lc"
+// CHECK-IOMP5-LD-32: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -target x86_64-unknown-linux -rtlib=platform \
 // RUN:   | FileCheck --check-prefix=CHECK-IOMP5-LD-64 %s
 // CHECK-IOMP5-LD-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-IOMP5-LD-64: "-l[[DEFAULT_OPENMP_LIB:[^"]*]]"
-// CHECK-IOMP5-LD-64: "-lpthread" "-latomic" "-lc"
+// CHECK-IOMP5-LD-64: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp=lib -target i386-unknown-linux \
@@ -71,7 +71,7 @@
 // RUN:   | FileCheck --check-prefix=CHECK-LD-OVERRIDE-32 %s
 // CHECK-LD-OVERRIDE-32: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-OVERRIDE-32: "-lgomp" "-lrt"
-// CHECK-LD-OVERRIDE-32: "-lpthread" "-latomic" "-lc"
+// CHECK-LD-OVERRIDE-32: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -fopenmp=libgomp -target x86_64-unknown-linux \
@@ -79,7 +79,7 @@
 // RUN:   | FileCheck --check-prefix=CHECK-LD-OVERRIDE-64 %s
 // CHECK-LD-OVERRIDE-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-OVERRIDE-64: "-lgomp" "-lrt"
-// CHECK-LD-OVERRIDE-64: "-lpthread" "-latomic" "-lc"
+// CHECK-LD-OVERRIDE-64: "-lpthread" "-lc"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp=libomp -target x86_64-msvc-win32 -rtlib=platform \