diff --git a/src/builder.rs b/src/builder.rs
index fd3710062ee45..10ee63e2a550c 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -1051,11 +1051,18 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
     }
 
     /* Comparisons */
-    fn icmp(&mut self, op: IntPredicate, lhs: RValue<'gcc>, mut rhs: RValue<'gcc>) -> RValue<'gcc> {
-        if lhs.get_type() != rhs.get_type() {
+    fn icmp(&mut self, op: IntPredicate, mut lhs: RValue<'gcc>, mut rhs: RValue<'gcc>) -> RValue<'gcc> {
+        let left_type = lhs.get_type();
+        let right_type = rhs.get_type();
+        if left_type != right_type {
+            // NOTE: because libgccjit cannot compare function pointers.
+            if left_type.is_function_ptr_type().is_some() && right_type.is_function_ptr_type().is_some() {
+                lhs = self.context.new_cast(None, lhs, self.usize_type.make_pointer());
+                rhs = self.context.new_cast(None, rhs, self.usize_type.make_pointer());
+            }
             // NOTE: hack because we try to cast a vector type to the same vector type.
-            if format!("{:?}", lhs.get_type()) != format!("{:?}", rhs.get_type()) {
-                rhs = self.context.new_cast(None, rhs, lhs.get_type());
+            else if format!("{:?}", left_type) != format!("{:?}", right_type) {
+                rhs = self.context.new_cast(None, rhs, left_type);
             }
         }
         self.context.new_comparison(None, op.to_gcc_comparison(), lhs, rhs)
@@ -1209,6 +1216,17 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
             else {
                 panic!("Unexpected type {:?}", value_type);
             };
+
+        let lvalue_type = lvalue.to_rvalue().get_type();
+        let value =
+            // NOTE: sometimes, rustc will create a value with the wrong type.
+            if lvalue_type != value.get_type() {
+                self.context.new_cast(None, value, lvalue_type)
+            }
+            else {
+                value
+            };
+
         self.llbb().add_assignment(None, lvalue, value);
 
         aggregate_value
diff --git a/test.sh b/test.sh
index 92cbdbb7c00db..944d0ce516e0f 100755
--- a/test.sh
+++ b/test.sh
@@ -17,6 +17,7 @@ export LIBRARY_PATH="$GCC_PATH"
 if [[ "$1" == "--release" ]]; then
     export CHANNEL='release'
     CARGO_INCREMENTAL=1 cargo rustc --release
+    shift
 else
     echo $LD_LIBRARY_PATH
     export CHANNEL='debug'
@@ -25,52 +26,60 @@ fi
 
 source config.sh
 
-rm -r target/out || true
-mkdir -p target/out/gccjit
+function clean() {
+    rm -r target/out || true
+    mkdir -p target/out/gccjit
+}
 
-echo "[BUILD] mini_core"
-$RUSTC example/mini_core.rs --crate-name mini_core --crate-type lib,dylib --target $TARGET_TRIPLE
+function mini_tests() {
+    echo "[BUILD] mini_core"
+    $RUSTC example/mini_core.rs --crate-name mini_core --crate-type lib,dylib --target $TARGET_TRIPLE
 
-echo "[BUILD] example"
-$RUSTC example/example.rs --crate-type lib --target $TARGET_TRIPLE
+    echo "[BUILD] example"
+    $RUSTC example/example.rs --crate-type lib --target $TARGET_TRIPLE
 
-echo "[AOT] mini_core_hello_world"
-$RUSTC example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/mini_core_hello_world abc bcd
+    echo "[AOT] mini_core_hello_world"
+    $RUSTC example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/mini_core_hello_world abc bcd
+}
 
-echo "[BUILD] sysroot"
-time ./build_sysroot/build_sysroot.sh
+function build_sysroot() {
+    echo "[BUILD] sysroot"
+    time ./build_sysroot/build_sysroot.sh
+}
 
-echo "[AOT] arbitrary_self_types_pointers_and_wrappers"
-$RUSTC example/arbitrary_self_types_pointers_and_wrappers.rs --crate-name arbitrary_self_types_pointers_and_wrappers --crate-type bin --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/arbitrary_self_types_pointers_and_wrappers
+function std_tests() {
+    echo "[AOT] arbitrary_self_types_pointers_and_wrappers"
+    $RUSTC example/arbitrary_self_types_pointers_and_wrappers.rs --crate-name arbitrary_self_types_pointers_and_wrappers --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/arbitrary_self_types_pointers_and_wrappers
 
-echo "[AOT] alloc_system"
-$RUSTC example/alloc_system.rs --crate-type lib --target "$TARGET_TRIPLE"
+    echo "[AOT] alloc_system"
+    $RUSTC example/alloc_system.rs --crate-type lib --target "$TARGET_TRIPLE"
 
-echo "[AOT] alloc_example"
-$RUSTC example/alloc_example.rs --crate-type bin --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/alloc_example
+    echo "[AOT] alloc_example"
+    $RUSTC example/alloc_example.rs --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/alloc_example
 
-echo "[AOT] dst_field_align"
-# FIXME(antoyo): Re-add -Zmir-opt-level=2 once rust-lang/rust#67529 is fixed.
-$RUSTC example/dst-field-align.rs --crate-name dst_field_align --crate-type bin --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/dst_field_align || (echo $?; false)
+    echo "[AOT] dst_field_align"
+    # FIXME(antoyo): Re-add -Zmir-opt-level=2 once rust-lang/rust#67529 is fixed.
+    $RUSTC example/dst-field-align.rs --crate-name dst_field_align --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/dst_field_align || (echo $?; false)
 
-echo "[AOT] std_example"
-$RUSTC example/std_example.rs --crate-type bin --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/std_example --target $TARGET_TRIPLE
+    echo "[AOT] std_example"
+    $RUSTC example/std_example.rs --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/std_example --target $TARGET_TRIPLE
 
-echo "[AOT] subslice-patterns-const-eval"
-$RUSTC example/subslice-patterns-const-eval.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/subslice-patterns-const-eval
+    echo "[AOT] subslice-patterns-const-eval"
+    $RUSTC example/subslice-patterns-const-eval.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/subslice-patterns-const-eval
 
-echo "[AOT] track-caller-attribute"
-$RUSTC example/track-caller-attribute.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
-$RUN_WRAPPER ./target/out/track-caller-attribute
+    echo "[AOT] track-caller-attribute"
+    $RUSTC example/track-caller-attribute.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/track-caller-attribute
 
-echo "[BUILD] mod_bench"
-$RUSTC example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
+    echo "[BUILD] mod_bench"
+    $RUSTC example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
+}
 
 # FIXME(antoyo): linker gives multiple definitions error on Linux
 #echo "[BUILD] sysroot in release mode"
@@ -95,11 +104,13 @@ $RUSTC example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
 #fi
 #popd
 
-pushd build_sysroot/sysroot_src/library/core/tests
-echo "[TEST] libcore"
-rm -r ./target || true
-../../../../../cargo.sh test
-popd
+function test_libcore() {
+    pushd build_sysroot/sysroot_src/library/core/tests
+    echo "[TEST] libcore"
+    rm -r ./target || true
+    ../../../../../cargo.sh test
+    popd
+}
 
 # TODO(antoyo): uncomment when it works.
 #pushd regex
@@ -130,20 +141,21 @@ popd
 #echo "[BENCH RUN] mod_bench"
 #hyperfine --runs ${RUN_RUNS:-10} ./target/out/mod_bench{,_inline} ./target/out/mod_bench_llvm_*
 
-echo
-echo "[TEST] rust-lang/rust"
+function test_rustc() {
+    echo
+    echo "[TEST] rust-lang/rust"
 
-rust_toolchain=$(cat rust-toolchain)
+    rust_toolchain=$(cat rust-toolchain)
 
-git clone https://github.com/rust-lang/rust.git || true
-cd rust
-git fetch
-git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(')
-export RUSTFLAGS=
+    git clone https://github.com/rust-lang/rust.git || true
+    cd rust
+    git fetch
+    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(')
+    export RUSTFLAGS=
 
-rm config.toml || true
+    rm config.toml || true
 
-cat > config.toml <<EOF
+    cat > config.toml <<EOF
 [rust]
 codegen-backends = []
 deny-warnings = false
@@ -154,24 +166,52 @@ local-rebuild = true
 rustc = "$HOME/.rustup/toolchains/$rust_toolchain-$TARGET_TRIPLE/bin/rustc"
 EOF
 
-rustc -V | cut -d' ' -f3 | tr -d '('
-git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(') src/test
-
-for test in $(rg -i --files-with-matches "//(\[\w+\])?~|// error-pattern:|// build-fail|// run-fail|-Cllvm-args" src/test/ui); do
-  rm $test
-done
-
-git checkout -- src/test/ui/issues/auxiliary/issue-3136-a.rs # contains //~ERROR, but shouldn't be removed
-
-rm -r src/test/ui/{abi*,extern/,llvm-asm/,panic-runtime/,panics/,unsized-locals/,proc-macro/,threads-sendsync/,thinlto/,simd*,borrowck/,test*,*lto*.rs} || true
-for test in $(rg --files-with-matches "catch_unwind|should_panic|thread|lto" src/test/ui); do
-  rm $test
-done
-git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs
-git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs
-rm src/test/ui/llvm-asm/llvm-asm-in-out-operand.rs || true # TODO(antoyo): Enable back this test if I ever implement the llvm_asm! macro.
-
-RUSTC_ARGS="-Zpanic-abort-tests -Zsymbol-mangling-version=v0 -Zcodegen-backend="$(pwd)"/../target/"$CHANNEL"/librustc_codegen_gcc."$dylib_ext" --sysroot "$(pwd)"/../build_sysroot/sysroot -Cpanic=abort"
-
-echo "[TEST] rustc test suite"
-COMPILETEST_FORCE_STAGE0=1 ./x.py test --run always --stage 0 src/test/ui/ --rustc-args "$RUSTC_ARGS"
+    rustc -V | cut -d' ' -f3 | tr -d '('
+    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(') src/test
+
+    for test in $(rg -i --files-with-matches "//(\[\w+\])?~|// error-pattern:|// build-fail|// run-fail|-Cllvm-args" src/test/ui); do
+      rm $test
+    done
+
+    git checkout -- src/test/ui/issues/auxiliary/issue-3136-a.rs # contains //~ERROR, but shouldn't be removed
+
+    rm -r src/test/ui/{abi*,extern/,llvm-asm/,panic-runtime/,panics/,unsized-locals/,proc-macro/,threads-sendsync/,thinlto/,simd*,borrowck/,test*,*lto*.rs} || true
+    for test in $(rg --files-with-matches "catch_unwind|should_panic|thread|lto" src/test/ui); do
+      rm $test
+    done
+    git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs
+    git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs
+    rm src/test/ui/llvm-asm/llvm-asm-in-out-operand.rs || true # TODO(antoyo): Enable back this test if I ever implement the llvm_asm! macro.
+
+    RUSTC_ARGS="-Zpanic-abort-tests -Zsymbol-mangling-version=v0 -Zcodegen-backend="$(pwd)"/../target/"$CHANNEL"/librustc_codegen_gcc."$dylib_ext" --sysroot "$(pwd)"/../build_sysroot/sysroot -Cpanic=abort"
+
+    echo "[TEST] rustc test suite"
+    COMPILETEST_FORCE_STAGE0=1 ./x.py test --run always --stage 0 src/test/ui/ --rustc-args "$RUSTC_ARGS"
+}
+
+function clean_ui_tests() {
+    find rust/build/x86_64-unknown-linux-gnu/test/ui/ -name stamp -exec rm -rf {} \;
+}
+
+case $1 in
+    "--test-rustc")
+        test_rustc
+        ;;
+
+    "--test-libcore")
+        test_libcore
+        ;;
+
+    "--clean-ui-tests")
+        clean_ui_tests
+        ;;
+
+    *)
+        clean
+        mini_tests
+        build_sysroot
+        std_tests
+        test_libcore
+        test_rustc
+        ;;
+esac