[WebAssembly] Enable -ffunction-sections and -fdata-sections by default.

These remain user-overridable with -fno-function-sections and
-fno-data-sections.

llvm-svn: 257005

1 files changed, 8 insertions, 3 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 0236e61..1584991 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -4176,8 +4176,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-generate-type-units");
   }
 
-  // CloudABI uses -ffunction-sections and -fdata-sections by default.
-  bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI;
+  // CloudABI and WebAssembly use -ffunction-sections and -fdata-sections by
+  // default.
+  bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI ||
+                             Triple.getArch() == llvm::Triple::wasm32 ||
+                             Triple.getArch() == llvm::Triple::wasm64;
 
   if (Args.hasFlag(options::OPT_ffunction_sections,
                    options::OPT_fno_function_sections, UseSeparateSections)) {
@@ -6536,7 +6539,9 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   CmdArgs.push_back("ld");
 
   // Enable garbage collection of unused input sections by default, since code
-  // size is of particular importance.
+  // size is of particular importance. This is significantly facilitated by
+  // the enabling of -ffunction-sections and -fdata-sections in
+  // Clang::ConstructJob.
   if (areOptimizationsEnabled(Args))
     CmdArgs.push_back("--gc-sections");