[clang] 579a807 - [Clang][Driver][ARM] Forward `-Os` and `-Oz` as multilib flags (#149819)

[via cfe-commits]

Author: Victor Campos
Date: 2025-07-22T10:57:44+01:00
New Revision: 579a80784d43f4c21ac4ee2df221ba4f3b98fd70

URL: https://github.com/llvm/llvm-project/commit/579a80784d43f4c21ac4ee2df221ba4f3b98fd70
DIFF: https://github.com/llvm/llvm-project/commit/579a80784d43f4c21ac4ee2df221ba4f3b98fd70.diff

LOG: [Clang][Driver][ARM] Forward `-Os` and `-Oz` as multilib flags (#149819)

Pass along `-Os` and `-Oz` as multilib flags under ARM and AArch64 so
that they can be used as criteria for multilib selection.

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 595ddddb23994..180452077dde1 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -217,6 +217,18 @@ static void getAArch64MultilibFlags(const Driver &D,
     Result.push_back(ABIArg->getAsString(Args));
   }
 
+  if (const Arg *A = Args.getLastArg(options::OPT_O_Group);
+      A && A->getOption().matches(options::OPT_O)) {
+    switch (A->getValue()[0]) {
+    case 's':
+      Result.push_back("-Os");
+      break;
+    case 'z':
+      Result.push_back("-Oz");
+      break;
+    }
+  }
+
   processMultilibCustomFlags(Result, Args);
 }
 
@@ -294,6 +306,19 @@ static void getARMMultilibFlags(const Driver &D, const llvm::Triple &Triple,
     if (Endian->getOption().matches(options::OPT_mbig_endian))
       Result.push_back(Endian->getAsString(Args));
   }
+
+  if (const Arg *A = Args.getLastArg(options::OPT_O_Group);
+      A && A->getOption().matches(options::OPT_O)) {
+    switch (A->getValue()[0]) {
+    case 's':
+      Result.push_back("-Os");
+      break;
+    case 'z':
+      Result.push_back("-Oz");
+      break;
+    }
+  }
+
   processMultilibCustomFlags(Result, Args);
 }
 

diff  --git a/clang/test/Driver/print-multi-selection-flags.c b/clang/test/Driver/print-multi-selection-flags.c
index 8cf8f04bb6b48..b1a0a29ec4180 100644
--- a/clang/test/Driver/print-multi-selection-flags.c
+++ b/clang/test/Driver/print-multi-selection-flags.c
@@ -126,3 +126,20 @@
 // CHECK-PIE1: -fpie
 // CHECK-ROPI: -fropi
 // CHECK-RWPI: -frwpi
+
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -Os | FileCheck --check-prefix=CHECK-OPT-OS %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -Oz | FileCheck --check-prefix=CHECK-OPT-OZ %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a     | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -O1 | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -O2 | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -O3 | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi -Os           | FileCheck --check-prefix=CHECK-OPT-OS %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi -Oz           | FileCheck --check-prefix=CHECK-OPT-OZ %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi               | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi -O1           | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi -O2           | FileCheck --check-prefix=CHECK-OPT %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=aarch64-none-eabi -O3           | FileCheck --check-prefix=CHECK-OPT %s
+// CHECK-OPT-OZ: -Oz
+// CHECK-OPT-OS: -Os
+// CHECK-OPT-NOT: -Oz
+// CHECK-OPT-NOT: -Os