Add CodeGen options to allow for specifying optimize for size and minimum size

options.
Closes #32296

Author: brandonedens

src/librustc/session/config.rs

@@ -564,6 +564,8 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
          2 = full debug info with variable and type information"),
     opt_level: Option<usize> = (None, parse_opt_uint,
         "optimize with possible levels 0-3"),
+    opt_size: Option<usize> = (None, parse_opt_uint,
+        "optimize for size levels 0-2"),
     debug_assertions: Option<bool> = (None, parse_opt_bool,
         "explicitly enable the cfg(debug_assertions) directive"),
     inline_threshold: Option<usize> = (None, parse_opt_uint,

src/librustc_trans/trans/declare.rs

@@ -69,6 +69,15 @@ fn declare_raw_fn(ccx: &CrateContext, name: &str, callconv: llvm::CallConv, ty:
         llvm::SetFunctionAttribute(llfn, llvm::Attribute::NoRedZone)
     }
 
+    let opt_size = ccx.tcx().sess.opts.cg.opt_size.unwrap_or(0);
+    if opt_size >= 1 {
+            llvm::SetFunctionAttribute(llfn, llvm::Attribute::OptimizeForSize);
+    }
+    if opt_size >= 2 {
+        llvm::SetFunctionAttribute(llfn, llvm::Attribute::MinSize);
+    }
+
+
     llfn
 }