[clang] cace477 - [clang][AArch64] multilib: fix deduction of "-march=" option (#81474)

[via cfe-commits]

Author: Dominik Wójt
Date: 2024-02-26T08:09:33+01:00
New Revision: cace477c0b6c3d9494ead66eb725c6e72f27b767

URL: https://github.com/llvm/llvm-project/commit/cace477c0b6c3d9494ead66eb725c6e72f27b767
DIFF: https://github.com/llvm/llvm-project/commit/cace477c0b6c3d9494ead66eb725c6e72f27b767.diff

LOG: [clang][AArch64] multilib: fix deduction of "-march=" option (#81474)

The deduced "-march=" option always started with aarch64, which is not a
valid value. There was also no way to distinguish between armv8-r and
armv8-a. After this commit, the deduced "-march=" option will start with
greatest available "armv*-a" value or "armv8-r".

Added: 
    

Modified: 
    clang/lib/Driver/ToolChain.cpp
    clang/test/Driver/print-multi-selection-flags.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index f8c13c86daf9b0..bd854aae35d4ce 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -200,7 +200,12 @@ static void getAArch64MultilibFlags(const Driver &D,
   for (const auto &Ext : AArch64::Extensions)
     if (FeatureSet.contains(Ext.NegFeature))
       MArch.push_back(("no" + Ext.Name).str());
-  MArch.insert(MArch.begin(), ("-march=" + Triple.getArchName()).str());
+  StringRef ArchName;
+  for (const auto &ArchInfo : AArch64::ArchInfos)
+    if (FeatureSet.contains(ArchInfo->ArchFeature))
+      ArchName = ArchInfo->Name;
+  assert(!ArchName.empty() && "at least one architecture should be found");
+  MArch.insert(MArch.begin(), ("-march=" + ArchName).str());
   Result.push_back(llvm::join(MArch, "+"));
 }
 

diff  --git a/clang/test/Driver/print-multi-selection-flags.c b/clang/test/Driver/print-multi-selection-flags.c
index 248d9a3cdf49b2..06a12db9d97792 100644
--- a/clang/test/Driver/print-multi-selection-flags.c
+++ b/clang/test/Driver/print-multi-selection-flags.c
@@ -51,9 +51,10 @@
 // CHECK-M85_NO_FP_DP: -mfpu=fp-armv8-fullfp16-sp-d16
 
 // RUN: %clang -print-multi-flags-experimental --target=aarch64-none-elf -march=armv8-a+lse | FileCheck --check-prefix=CHECK-LSE %s
-// CHECK-LSE: -march=aarch64{{.*}}+lse{{.*}}
+// CHECK-LSE: --target=aarch64-none-unknown-elf
+// CHECK-LSE: -march=armv8-a{{.*}}+lse{{.*}}
 
 // RUN: %clang -print-multi-flags-experimental --target=aarch64-none-elf -march=armv8.5-a+sve+sve2 | FileCheck --check-prefix=CHECK-SVE2 %s
 // RUN: %clang -print-multi-flags-experimental --target=aarch64-none-elf -march=armv9-a            | FileCheck --check-prefix=CHECK-SVE2 %s
 // CHECK-SVE2: --target=aarch64-none-unknown-elf
-// CHECK-SVE2: -march=aarch64{{.*}}+simd{{.*}}+sve{{.*}}+sve2{{.*}}
+// CHECK-SVE2: -march=armv{{.*}}-a{{.*}}+simd{{.*}}+sve{{.*}}+sve2{{.*}}