[RISCV][Clang] Remove -save-restore from default features. (#76390)

It's unnecessary to defaultly pass feature `-save-restore`, since risc-v
backend defaultly disables save-restore functionality.

Author: yetingk

clang/lib/Driver/ToolChains/Arch/RISCV.cpp

@@ -167,13 +167,6 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
     Features.push_back("-relax");
   }
 
-  // GCC Compatibility: -mno-save-restore is default, unless -msave-restore is
-  // specified.
-  if (Args.hasFlag(options::OPT_msave_restore, options::OPT_mno_save_restore, false))
-    Features.push_back("+save-restore");
-  else
-    Features.push_back("-save-restore");
-
   // -mno-unaligned-access is default, unless -munaligned-access is specified.
   AddTargetFeature(Args, Features, options::OPT_munaligned_access,
                    options::OPT_mno_unaligned_access, "fast-unaligned-access");

clang/test/Driver/riscv-default-features.c

@@ -2,9 +2,7 @@
 // RUN: %clang --target=riscv64-unknown-elf -S -emit-llvm %s -o - | FileCheck %s -check-prefix=RV64
 
 // RV32: "target-features"="+32bit,+a,+c,+m,+relax,
-// RV32-SAME: -save-restore
 // RV64: "target-features"="+64bit,+a,+c,+m,+relax,
-// RV64-SAME: -save-restore
 
 // Dummy function
 int foo(void){

clang/test/Driver/riscv-features.c

@@ -24,7 +24,7 @@
 
 // SAVE-RESTORE: "-target-feature" "+save-restore"
 // NO-SAVE-RESTORE: "-target-feature" "-save-restore"
-// DEFAULT: "-target-feature" "-save-restore"
+// DEFAULT-NOT: "-target-feature" "-save-restore"
 // DEFAULT-NOT: "-target-feature" "+save-restore"
 
 // RUN: %clang --target=riscv32-unknown-elf -### %s -munaligned-access 2>&1 | FileCheck %s -check-prefix=FAST-UNALIGNED-ACCESS