Set cranelift opt_level based on -Copt-level

bjorn3 · Nov 16, 2018 · 8233ade · 8233ade
1 parent e663450
commit 8233ade
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Showing 2 changed files with 16 additions and 1 deletion.
diff --git a/build.sh b/build.sh
@@ -63,7 +63,7 @@ rm -r target || true
 time RUSTFLAGS="-Zmir-opt-level=3 $RUSTFLAGS" xargo build
 popd
 
-$RUSTC --sysroot ~/.xargo/HOST example/mod_bench.rs --crate-type bin -Zmir-opt-level=3 --crate-name mod_bench_inline
+$RUSTC --sysroot ~/.xargo/HOST example/mod_bench.rs --crate-type bin -Zmir-opt-level=3 -Og --crate-name mod_bench_inline
 
 rustc example/mod_bench.rs --crate-type bin -Copt-level=0 -o target/out/mod_bench_llvm_0 -Cpanic=abort
 rustc example/mod_bench.rs --crate-type bin -Copt-level=1 -o target/out/mod_bench_llvm_1 -Cpanic=abort

diff --git a/src/lib.rs b/src/lib.rs
@@ -329,6 +329,21 @@ impl CodegenBackend for CraneliftCodegenBackend {
 
         let mut flags_builder = settings::builder();
         flags_builder.enable("is_pic").unwrap();
+
+        use rustc::session::config::OptLevel;
+        match tcx.sess.opts.optimize {
+            OptLevel::No => {
+                flags_builder.set("opt_level", "fastest").unwrap();
+            },
+            OptLevel::Less | OptLevel::Default => {},
+            OptLevel::Aggressive => {
+                flags_builder.set("opt_level", "best").unwrap();
+            },
+            OptLevel::Size | OptLevel::SizeMin => {
+                tcx.sess.warn("Optimizing for size is not supported. Just ignoring the request");
+            }
+        }
+
         let flags = settings::Flags::new(flags_builder);
         let isa =
             cranelift::codegen::isa::lookup(tcx.sess.target.target.llvm_target.parse().unwrap())