[clang] [Clang][RISCV] Forward --no-relax option to linker for RISC-V (PR #76432)

[Andreu Carminati via cfe-commits]

https://github.com/andcarminati created https://github.com/llvm/llvm-project/pull/76432

In the case of -mno-relax option. Otherwise, we cannot prevent relaxation if we split compilation and linking using Clang driver.

One can consider the following use case:

clang [...] -c -o myobject.o (just compile)
clang [...] myobject.o -o myobject.elf -mno-relax (linking)

In this case, myobject.elf will be relaxed, the -mno-relax will be silently ignored.

>From 13648eaf3becc5650924c3399fb1dc1ecb9fa7c7 Mon Sep 17 00:00:00 2001
From: Andreu Carminati <andreu.carminati at hightec-rt.com>
Date: Wed, 27 Dec 2023 09:47:54 +0100
Subject: [PATCH] [Clang][RISCV] Forward --no-relax option to linker for RISC-V

In the case of -mno-relax option. Otherwise, we cannot prevent relaxation
if we split compilation and linking using Clang driver.

One can consider the following use case:

clang [...] -c -o myobject.o (just compile)
clang [...] myobject.o -o myobject.elf -mno-relax (linking)

In this case, myobject.elf will be relaxed, the -mno-relax will be silently ignored.
---
 clang/lib/Driver/ToolChains/BareMetal.cpp      |  3 +++
 clang/lib/Driver/ToolChains/RISCVToolchain.cpp |  3 +++
 clang/test/Driver/baremetal.cpp                | 12 ++++++++++++
 clang/test/Driver/riscv32-toolchain.c          | 16 ++++++++++++++++
 clang/test/Driver/riscv64-toolchain.c          | 16 ++++++++++++++++
 5 files changed, 50 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
index 42c8336e626c7b..007a24f2b81ae7 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.cpp
+++ b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -443,6 +443,9 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   CmdArgs.push_back("-Bstatic");
 
+  if (TC.getTriple().isRISCV() && Args.hasArg(options::OPT_mno_relax))
+    CmdArgs.push_back("--no-relax");
+
   if (Triple.isARM() || Triple.isThumb()) {
     bool IsBigEndian = arm::isARMBigEndian(Triple, Args);
     if (IsBigEndian)
diff --git a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
index 7e6abd14442878..0be7d1a8899495 100644
--- a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
+++ b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
@@ -156,6 +156,9 @@ void RISCV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (!D.SysRoot.empty())
     CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
 
+  if (Args.hasArg(options::OPT_mno_relax))
+    CmdArgs.push_back("--no-relax");
+
   bool IsRV64 = ToolChain.getArch() == llvm::Triple::riscv64;
   CmdArgs.push_back("-m");
   if (IsRV64) {
diff --git a/clang/test/Driver/baremetal.cpp b/clang/test/Driver/baremetal.cpp
index c04f4506a0994d..7511d7d1adb4dd 100644
--- a/clang/test/Driver/baremetal.cpp
+++ b/clang/test/Driver/baremetal.cpp
@@ -460,3 +460,15 @@
 // RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-ARCH %s
 // CHECK-CLANGRT-ARCH: "-lclang_rt.builtins-armv6m"
 // CHECK-CLANGRT-ARCH-NOT: "-lclang_rt.builtins"
+
+// Check that "--no-relax" is forwarded to the linker for RISC-V.
+// RUN: %clang %s -### 2>&1 --target=riscv64-unknown-elf -nostdinc -mno-relax \
+// RUN:     --sysroot=%S/Inputs/basic_riscv64_tree/riscv64-unknown-elf \
+// RUN:   | FileCheck --check-prefix=CHECK-RV64-NORELAX %s
+// CHECK-RV64-NORELAX: "--no-relax"
+
+// Check that "--no-relax" is not forwarded to the linker for RISC-V.
+// RUN: %clang %s -### 2>&1 --target=riscv64-unknown-elf -nostdinc \
+// RUN:     --sysroot=%S/Inputs/basic_riscv64_tree/riscv64-unknown-elf \
+// RUN:   | FileCheck --check-prefix=CHECK-RV64-RELAX %s
+// CHECK-RV64-RELAX-NOT: "--no-relax"
\ No newline at end of file
diff --git a/clang/test/Driver/riscv32-toolchain.c b/clang/test/Driver/riscv32-toolchain.c
index 63690c946ca0bc..701da05da9189d 100644
--- a/clang/test/Driver/riscv32-toolchain.c
+++ b/clang/test/Driver/riscv32-toolchain.c
@@ -215,6 +215,22 @@
 
 // RUN: %clang --target=riscv32 %s -emit-llvm -S -o - | FileCheck %s
 
+// Check that "--no-relax" is forwarded to the linker for RISC-V (RISCVToolchain.cpp).
+// RUN: env "PATH=" %clang %s -### 2>&1 -mno-relax \
+// RUN:   --target=riscv32-unknown-elf --rtlib=platform --unwindlib=platform --sysroot= \
+// RUN:   -march=rv32imac -mabi=lp32\
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_elf_sdk 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-RV32-NORELAX %s
+// CHECK-RV32-NORELAX: "--no-relax"
+
+// Check that "--no-relax" is not forwarded to the linker for RISC-V (RISCVToolchain.cpp).
+// RUN:env "PATH=" %clang %s -### 2>&1 \
+// RUN:   --target=riscv32-unknown-elf --rtlib=platform --unwindlib=platform --sysroot= \
+// RUN:   -march=rv32imac -mabi=lp32\
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_elf_sdk 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-RV32-RELAX %s
+// CHECK-RV32-RELAX-NOT: "--no-relax"
+
 typedef __builtin_va_list va_list;
 typedef __SIZE_TYPE__ size_t;
 typedef __PTRDIFF_TYPE__ ptrdiff_t;
diff --git a/clang/test/Driver/riscv64-toolchain.c b/clang/test/Driver/riscv64-toolchain.c
index f177bff33dd4d7..da07c57d8e1fc4 100644
--- a/clang/test/Driver/riscv64-toolchain.c
+++ b/clang/test/Driver/riscv64-toolchain.c
@@ -171,6 +171,22 @@
 
 // RUN: %clang --target=riscv64 %s -emit-llvm -S -o - | FileCheck %s
 
+// Check that "--no-relax" is forwarded to the linker for RISC-V (RISCVToolchain.cpp).
+// RUN: env "PATH=" %clang %s -### 2>&1 -mno-relax \
+// RUN:   --target=riscv64-unknown-elf --rtlib=platform --unwindlib=platform --sysroot= \
+// RUN:   -march=rv64imac -mabi=lp64\
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_elf_sdk 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-RV64-NORELAX %s
+// CHECK-RV64-NORELAX: "--no-relax"
+
+// Check that "--no-relax" is not forwarded to the linker for RISC-V (RISCVToolchain.cpp).
+// RUN:env "PATH=" %clang %s -### 2>&1 \
+// RUN:   --target=riscv64-unknown-elf --rtlib=platform --unwindlib=platform --sysroot= \
+// RUN:   -march=rv64imac -mabi=lp64\
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_elf_sdk 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-RV64-RELAX %s
+// CHECK-RV64-RELAX-NOT: "--no-relax"
+
 typedef __builtin_va_list va_list;
 typedef __SIZE_TYPE__ size_t;
 typedef __PTRDIFF_TYPE__ ptrdiff_t;