https://github.com/kiranchandramohan updated
https://github.com/llvm/llvm-project/pull/144710
>From 2c278271277823b3544d991365e58f97dd4b7031 Mon Sep 17 00:00:00 2001
From: David Truby <david.tr...@arm.com>
Date: Wed, 18 Jun 2025 10:17:05 +0100
Subject: [PATCH] [flang][AArch64] Always compiler-rt to flang linking after
libgcc
This patch fixes an issue where the __trampoline_setup symbol is missing
with some programs compiled with flang. This symbol is present only in
compiler-rt and not in libgcc. This patch adds compiler-rt to the link
line after libgcc if libgcc is being used, so that only this symbol will
be picked from compiler-rt.
---
clang/lib/Driver/ToolChains/CommonArgs.cpp | 7 +++++++
flang/test/Driver/flang-ld-aarch64.f90 | 9 +++++++++
llvm/CMakeLists.txt | 7 +++++++
3 files changed, 23 insertions(+)
create mode 100644 flang/test/Driver/flang-ld-aarch64.f90
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index d5b2c5c1e199e..672b73432847d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -2252,6 +2252,13 @@ static void AddLibgcc(const ToolChain &TC, const Driver
&D,
if (LGT == LibGccType::SharedLibGcc ||
(LGT == LibGccType::UnspecifiedLibGcc && D.CCCIsCXX()))
CmdArgs.push_back("-lgcc");
+ // compiler-rt is needed after libgcc for flang on AArch64 for the
+ // __trampoline_setup symbol
+ if (D.IsFlangMode() && TC.getArch() == llvm::Triple::aarch64) {
+ CmdArgs.push_back("--as-needed");
+ CmdArgs.push_back(TC.getCompilerRTArgString(Args, "builtins"));
+ CmdArgs.push_back("--no-as-needed");
+ }
}
void tools::AddRunTimeLibs(const ToolChain &TC, const Driver &D,
diff --git a/flang/test/Driver/flang-ld-aarch64.f90
b/flang/test/Driver/flang-ld-aarch64.f90
new file mode 100644
index 0000000000000..61cd46cea5cd1
--- /dev/null
+++ b/flang/test/Driver/flang-ld-aarch64.f90
@@ -0,0 +1,9 @@
+! Check linker flags for AArch64 linux, since it needs both libgcc and
+! compiler-rt, with compiler-rt second when -rtlib=libgcc.
+
+! RUN: %flang -### -rtlib=libgcc --target=aarch64-linux-gnu
%S/Inputs/hello.f90 2>&1 | FileCheck %s
+
+! CHECK-LABEL: "{{.*}}ld{{(\.exe)?}}"
+! CHECK-SAME: "-lflang_rt.runtime" "-lm"
+! CHECK-SAME: "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
+! CHECK-SAME: "--as-needed" "{{.*}}{{\\|/}}libclang_rt.builtins.a"
"--no-as-needed"
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 0849bec26d56a..1b91e45c202e3 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -653,6 +653,13 @@ if(LLVM_EXPERIMENTAL_TARGETS_TO_BUILD STREQUAL "all")
set(LLVM_EXPERIMENTAL_TARGETS_TO_BUILD ${LLVM_ALL_EXPERIMENTAL_TARGETS})
endif()
+if("flang" IN_LIST LLVM_ENABLE_PROJECTS AND
+ "AArch64" IN_LIST LLVM_TARGETS_TO_BUILD AND
+ NOT "compiler-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
+ message(STATUS "Enabling Flang-RT as a dependency of Flang")
+ list(APPEND LLVM_ENABLE_RUNTIMES "compiler-rt")
+endif()
+
set(LLVM_TARGETS_TO_BUILD
${LLVM_TARGETS_TO_BUILD}
${LLVM_EXPERIMENTAL_TARGETS_TO_BUILD})
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