[clang] [RISCV] Simply add the march/mabi strings to Flags for selecting multilib (PR #180104)

[Jim Lin via cfe-commits]

https://github.com/tclin914 created https://github.com/llvm/llvm-project/pull/180104

It does't need to compare the march/mabi with multilib's before adding such string into Flags. The negative one (!march/!mabi) has no effect during multilib selection. We can select either a multilib with identical march and mabi, or one with a subset of march and the same mabi.

>From 221358003a70dae9396b164df9908dea0fe7be50 Mon Sep 17 00:00:00 2001
From: Jim Lin <jim at andestech.com>
Date: Thu, 5 Feb 2026 13:57:02 +0800
Subject: [PATCH] [RISCV] Simply add the march/mabi strings to Flags for
 selecting multilib

It does't need to compare the march/mabi with multilib's before adding
such string into Flags. The negative one (!march/!mabi) has no effect
during multilib selection. We can select either a multilib with
identical march and mabi, or one with a subset of march and the same
mabi.
---
 clang/lib/Driver/ToolChains/Gnu.cpp | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index ac31a45b557f1..215a50612a31d 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -1631,7 +1631,7 @@ selectRISCVMultilib(const Driver &D, const MultilibSet &RISCVMultilibSet,
 
   // Collect all flags except march=*
   for (StringRef Flag : Flags) {
-    if (Flag.starts_with("!march=") || Flag.starts_with("-march="))
+    if (Flag.starts_with("-march="))
       continue;
 
     NewFlags.push_back(Flag.str());
@@ -1753,15 +1753,8 @@ static void findRISCVBareMetalMultilibs(const Driver &D,
   llvm::StringSet<> Added_ABIs;
   StringRef ABIName = tools::riscv::getRISCVABI(Args, TargetTriple);
   std::string MArch = tools::riscv::getRISCVArch(Args, TargetTriple);
-  for (auto Element : RISCVMultilibSet) {
-    addMultilibFlag(MArch == Element.march,
-                    Twine("-march=", Element.march).str(), Flags);
-    if (!Added_ABIs.count(Element.mabi)) {
-      Added_ABIs.insert(Element.mabi);
-      addMultilibFlag(ABIName == Element.mabi,
-                      Twine("-mabi=", Element.mabi).str(), Flags);
-    }
-  }
+  Flags.push_back("-march=" + MArch);
+  Flags.push_back("-mabi=" + ABIName.str());
 
   if (selectRISCVMultilib(D, RISCVMultilibs, MArch, Flags,
                           Result.SelectedMultilibs))