From 67013ee5feecca0c1e1dd8a149b20779a9b6c12a Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton@redhat.com>
Date: Wed, 23 Sep 2020 12:47:30 +0000
Subject: [PATCH] Driver: Prefer gcc toolchains with libgcc_s.so when not
static linking libgcc
Fedora ships cross-compilers on all platforms, so a user could end up
with a gcc x86_64 cross-compiler installed on an x86_64 system. clang
maintains a list of supported triples for each target and when all
else is equal will prefer toolchains with triples that appear earlier
in the list.
The cross-compiler triple on Fedora is x86_64-linux-gnu and this comes
before the Fedora system compiler's triple: x86_64-redhat-linux in
the triples list, so the cross compiler is always preferred. This
is a problem, because the cross compiler is missing libraries, like
libgcc_s.so, that clang expects to be there so linker invocations
will fail.
This patch fixes this by checking for the existence of libgcc_s.so
when it is required and taking that into account when selecting a
toolchain.
---
lib/Driver/ToolChains/Gnu.cpp | 16 ++++++++++++++--
lib/Driver/ToolChains/Gnu.h | 4 +++-
.../usr/lib/gcc/x86_64-linux-gnu/7/crtbegin.o | 0
.../usr/lib/gcc/x86_64-redhat-linux/7/crtbegin.o | 0
.../lib/gcc/x86_64-redhat-linux/7/libgcc_s.so | 0
test/Driver/linux-ld.c | 12 ++++++++++++
6 files changed, 29 insertions(+), 3 deletions(-)
create mode 100644 test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-linux-gnu/7/crtbegin.o
create mode 100644 test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/crtbegin.o
create mode 100644 test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/libgcc_s.so
diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
index c8a7fce0..f28792b7 100644
--- a/lib/Driver/ToolChains/Gnu.cpp
+++ b/lib/Driver/ToolChains/Gnu.cpp
@@ -2500,6 +2500,8 @@ void Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple(
(TargetArch == llvm::Triple::x86 &&
TargetTriple.getOS() != llvm::Triple::Solaris)}};
+ bool NeedLibgccShared = !Args.hasArg(options::OPT_static_libgcc) &&
+ !Args.hasArg(options::OPT_static);
for (auto &Suffix : Suffixes) {
if (!Suffix.Active)
continue;
@@ -2517,8 +2519,17 @@ void Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple(
continue; // Saw this path before; no need to look at it again.
if (CandidateVersion.isOlderThan(4, 1, 1))
continue;
- if (CandidateVersion <= Version)
- continue;
+
+ bool CandidateHasLibGccShared = false;
+ if (CandidateVersion <= Version) {
+ if (NeedLibgccShared && !HasLibGccShared) {
+ CandidateHasLibGccShared =
+ D.getVFS().exists(LI->path() + "/libgcc_s.so");
+
+ }
+ if (HasLibGccShared || !CandidateHasLibGccShared)
+ continue;
+ }
if (!ScanGCCForMultilibs(TargetTriple, Args, LI->path(),
NeedsBiarchSuffix))
@@ -2532,6 +2543,7 @@ void Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple(
GCCInstallPath = (LibDir + "/" + LibSuffix + "/" + VersionText).str();
GCCParentLibPath = (GCCInstallPath + "/../" + Suffix.ReversePath).str();
IsValid = true;
+ HasLibGccShared = CandidateHasLibGccShared;
}
}
}
diff --git a/lib/Driver/ToolChains/Gnu.h b/lib/Driver/ToolChains/Gnu.h
index 52690ab4..2a4452d9 100644
--- a/lib/Driver/ToolChains/Gnu.h
+++ b/lib/Driver/ToolChains/Gnu.h
@@ -190,6 +190,7 @@ public:
/// Driver, and has logic for fuzzing that where appropriate.
class GCCInstallationDetector {
bool IsValid;
+ bool HasLibGccShared;
llvm::Triple GCCTriple;
const Driver &D;
@@ -213,7 +214,8 @@ public:
MultilibSet Multilibs;
public:
- explicit GCCInstallationDetector(const Driver &D) : IsValid(false), D(D) {}
+ explicit GCCInstallationDetector(const Driver &D)
+ : IsValid(false), HasLibGccShared(false), D(D) {}
void init(const llvm::Triple &TargetTriple, const llvm::opt::ArgList &Args,
ArrayRef<std::string> ExtraTripleAliases = None);
diff --git a/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-linux-gnu/7/crtbegin.o b/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-linux-gnu/7/crtbegin.o
new file mode 100644
index 00000000..e69de29b
diff --git a/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/crtbegin.o b/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/crtbegin.o
new file mode 100644
index 00000000..e69de29b
diff --git a/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/libgcc_s.so b/test/Driver/Inputs/fedora_28_tree/usr/lib/gcc/x86_64-redhat-linux/7/libgcc_s.so
new file mode 100644
index 00000000..e69de29b
diff --git a/test/Driver/linux-ld.c b/test/Driver/linux-ld.c
index ec539522..95725d5c 100644
--- a/test/Driver/linux-ld.c
+++ b/test/Driver/linux-ld.c
@@ -784,6 +784,18 @@
// CHECK-FEDORA-31-RISCV64: "{{.*}}/usr/lib/gcc/riscv64-redhat-linux/9{{/|\\\\}}crtend.o"
// CHECK-FEDORA-31-RISCV64: "{{.*}}/usr/lib/gcc/riscv64-redhat-linux/9{{/|\\\\}}crtn.o"
//
+// Check that clang does not select the cross compiler by default on Fedora 28.
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN: --target=x86_64-unknown-linux-gnu \
+// RUN: --gcc-toolchain="" \
+// RUN: --sysroot=%S/Inputs/fedora_28_tree \
+// RUN: | FileCheck --check-prefix=CHECK-FEDORA-28-X86_64 %s
+//
+// CHECK-FEDORA-28-X86_64: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
+// CHECK-FEDORA-28-X86_64: "[[SYSROOT]]/usr/lib/gcc/x86_64-redhat-linux/7/crtbegin.o"
+// CHECK-FEDORA-28-X86_64: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-redhat-linux/7"
+//
// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
// RUN: --target=arm-unknown-linux-gnueabi -rtlib=platform \
// RUN: --gcc-toolchain="" \
--
2.25.2