[llvm-branch-commits] [clang] [Multilib] Add -fmultilib-flag command-line option (PR #110658)

[Victor Campos via llvm-branch-commits]

https://github.com/vhscampos updated https://github.com/llvm/llvm-project/pull/110658

>From c0bb75d7ba6292a0267d71026324164a11910ce8 Mon Sep 17 00:00:00 2001
From: Victor Campos <victor.campos at arm.com>
Date: Thu, 26 Sep 2024 14:44:01 +0100
Subject: [PATCH] [Multilib] Add -fmultilib-flag command-line option

This option is passed through to the multilib system. It is then used in
conjunction with other options to select the proper library variant.

Details about this change can be found in this thread:
https://discourse.llvm.org/t/rfc-multilib-custom-flags/81058
---
 clang/include/clang/Driver/Options.td           |  2 ++
 clang/lib/Driver/ToolChain.cpp                  | 12 ++++++++++++
 clang/test/Driver/print-multi-selection-flags.c |  7 +++++++
 3 files changed, 21 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index f2f9c20c9bc264..4ec23b270f2e6b 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5704,6 +5704,8 @@ def print_multi_directory : Flag<["-", "--"], "print-multi-directory">;
 def print_multi_lib : Flag<["-", "--"], "print-multi-lib">;
 def print_multi_flags : Flag<["-", "--"], "print-multi-flags-experimental">,
   HelpText<"Print the flags used for selecting multilibs (experimental)">;
+def fmultilib_flag : Joined<["-", "--"], "fmultilib-flag=">,
+  Visibility<[ClangOption]>;
 def print_multi_os_directory : Flag<["-", "--"], "print-multi-os-directory">,
   Flags<[Unsupported]>;
 def print_target_triple : Flag<["-", "--"], "print-target-triple">,
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 0d426a467e9a3b..bb8a4d6915e641 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -196,6 +196,15 @@ bool ToolChain::defaultToIEEELongDouble() const {
   return PPC_LINUX_DEFAULT_IEEELONGDOUBLE && getTriple().isOSLinux();
 }
 
+static void processMultilibCustomFlags(Multilib::flags_list &List,
+                                       const llvm::opt::ArgList &Args) {
+  for (const Arg *MultilibFlagArg :
+       Args.filtered(options::OPT_fmultilib_flag)) {
+    List.push_back(MultilibFlagArg->getAsString(Args));
+    MultilibFlagArg->claim();
+  }
+}
+
 static void getAArch64MultilibFlags(const Driver &D,
                                           const llvm::Triple &Triple,
                                           const llvm::opt::ArgList &Args,
@@ -246,6 +255,8 @@ static void getAArch64MultilibFlags(const Driver &D,
   if (ABIArg) {
     Result.push_back(ABIArg->getAsString(Args));
   }
+
+  processMultilibCustomFlags(Result, Args);
 }
 
 static void getARMMultilibFlags(const Driver &D,
@@ -313,6 +324,7 @@ static void getARMMultilibFlags(const Driver &D,
     if (Endian->getOption().matches(options::OPT_mbig_endian))
       Result.push_back(Endian->getAsString(Args));
   }
+  processMultilibCustomFlags(Result, Args);
 }
 
 static void getRISCVMultilibFlags(const Driver &D, const llvm::Triple &Triple,
diff --git a/clang/test/Driver/print-multi-selection-flags.c b/clang/test/Driver/print-multi-selection-flags.c
index 5bf6dca5096a73..cf9522aa068524 100644
--- a/clang/test/Driver/print-multi-selection-flags.c
+++ b/clang/test/Driver/print-multi-selection-flags.c
@@ -90,3 +90,10 @@
 // CHECK-RV32E-ORDER: --target=riscv32-unknown-none-elf
 // CHECK-RV32E-ORDER: -mabi=ilp32e
 // CHECK-RV32E-ORDER: -march=rv32e{{[0-9]+p[0-9]+}}_c{{[0-9]+p[0-9]+}}_zicsr{{[0-9]+p[0-9]+}}
+
+// RUN: %clang -print-multi-flags-experimental --target=armv8m.main-none-eabi -fmultilib-flag=foo -fmultilib-flag=bar | FileCheck --check-prefixes=CHECK-MULTILIB-CUSTOM-FLAG,CHECK-ARM-MULTILIB-CUSTOM-FLAG %s
+// RUN: %clang -print-multi-flags-experimental --target=aarch64-none-eabi     -fmultilib-flag=foo -fmultilib-flag=bar | FileCheck --check-prefixes=CHECK-MULTILIB-CUSTOM-FLAG,CHECK-AARCH64-MULTILIB-CUSTOM-FLAG %s
+// CHECK-ARM-MULTILIB-CUSTOM-FLAG:     --target=thumbv8m.main-unknown-none-eabi
+// CHECK-AARCH64-MULTILIB-CUSTOM-FLAG: --target=aarch64-unknown-none-eabi
+// CHECK-MULTILIB-CUSTOM-FLAG-DAG:     -fmultilib-flag=foo
+// CHECK-MULTILIB-CUSTOM-FLAG-DAG:     -fmultilib-flag=bar