Add missing cast and change some bitcasts to casts to avoid a gimple verification failure (rust-lang#100)

Author: antoyo

Readme.md

@@ -111,6 +111,8 @@ Or add a breakpoint to `add_error` in gdb and print the line number using:
 p loc->m_line
 ```
 
+To get the `rustc` command to run in `gdb`, add the `--verbose` flag to `cargo build`.
+
 ### How to use a custom-build rustc
 
  * Build the stage2 compiler (`rustup toolchain link debug-current build/x86_64-unknown-linux-gnu/stage2`).

src/back/write.rs

@@ -1,4 +1,4 @@
-use std::fs;
+use std::{env, fs};
 
 use gccjit::OutputKind;
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
@@ -42,17 +42,17 @@ pub(crate) unsafe fn codegen(cgcx: &CodegenContext<GccCodegenBackend>, _diag_han
                 let _timer = cgcx
                     .prof
                     .generic_activity_with_arg("LLVM_module_codegen_emit_obj", &module.name[..]);
-                match &*module.name {
-                    "std_example.7rcbfp3g-cgu.15" => {
-                        println!("Dumping reproducer {}", module.name);
-                        let _ = fs::create_dir("/tmp/reproducers");
-                        // FIXME(antoyo): segfault in dump_reproducer_to_file() might be caused by
-                        // transmuting an rvalue to an lvalue.
-                        // Segfault is actually in gcc::jit::reproducer::get_identifier_as_lvalue
-                        context.dump_reproducer_to_file(&format!("/tmp/reproducers/{}.c", module.name));
-                        println!("Dumped reproducer {}", module.name);
-                    },
-                    _ => (),
+                if env::var("CG_GCCJIT_DUMP_MODULE_NAMES").as_deref() == Ok("1") {
+                    println!("Module {}", module.name);
+                }
+                if env::var("CG_GCCJIT_DUMP_MODULE").as_deref() == Ok(&module.name) {
+                    println!("Dumping reproducer {}", module.name);
+                    let _ = fs::create_dir("/tmp/reproducers");
+                    // FIXME(antoyo): segfault in dump_reproducer_to_file() might be caused by
+                    // transmuting an rvalue to an lvalue.
+                    // Segfault is actually in gcc::jit::reproducer::get_identifier_as_lvalue
+                    context.dump_reproducer_to_file(&format!("/tmp/reproducers/{}.c", module.name));
+                    println!("Dumped reproducer {}", module.name);
                 }
                 context.compile_to_file(OutputKind::ObjectFile, obj_out.to_str().expect("path to str"));
             }

src/intrinsic/mod.rs

@@ -525,7 +525,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
 
         let value =
             if result_type.is_signed(self.cx) {
-                self.context.new_bitcast(None, value, typ)
+                self.context.new_cast(None, value, typ)
             }
             else {
                 value
@@ -689,7 +689,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
                 },
             };
 
-        self.context.new_bitcast(None, result, result_type)
+        self.context.new_cast(None, result, result_type)
     }
 
     fn count_leading_zeroes(&self, width: u64, arg: RValue<'gcc>) -> RValue<'gcc> {
@@ -740,6 +740,11 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
                 let not_low = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, low);
                 let not_low_and_not_high = not_low & not_high;
                 let index = not_high + not_low_and_not_high;
+                // NOTE: the following cast is necessary to avoid a GIMPLE verification failure in
+                // gcc.
+                // TODO(antoyo): do the correct verification in libgccjit to avoid an error at the
+                // compilation stage.
+                let index = self.context.new_cast(None, index, self.i32_type);
 
                 let res = self.context.new_array_access(None, result, index);
 
@@ -763,7 +768,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let arg =
             if result_type.is_signed(self.cx) {
                 let new_type = result_type.to_unsigned(self.cx);
-                self.context.new_bitcast(None, arg, new_type)
+                self.context.new_cast(None, arg, new_type)
             }
             else {
                 arg
@@ -815,10 +820,15 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
                 let not_high = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, high);
                 let not_low_and_not_high = not_low & not_high;
                 let index = not_low + not_low_and_not_high;
+                // NOTE: the following cast is necessary to avoid a GIMPLE verification failure in
+                // gcc.
+                // TODO(antoyo): do the correct verification in libgccjit to avoid an error at the
+                // compilation stage.
+                let index = self.context.new_cast(None, index, self.i32_type);
 
                 let res = self.context.new_array_access(None, result, index);
 
-                return self.context.new_bitcast(None, res, result_type);
+                return self.context.new_cast(None, res, result_type);
             }
             else {
                 unimplemented!("count_trailing_zeroes for {:?}", arg_type);
@@ -832,7 +842,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
                 arg
             };
         let res = self.context.new_call(None, count_trailing_zeroes, &[arg]);
-        self.context.new_bitcast(None, res, result_type)
+        self.context.new_cast(None, res, result_type)
     }
 
     fn int_width(&self, typ: Type<'gcc>) -> i64 {
@@ -846,7 +856,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
 
         let value =
             if result_type.is_signed(self.cx) {
-                self.context.new_bitcast(None, value, value_type)
+                self.context.new_cast(None, value, value_type)
             }
             else {
                 value
@@ -862,7 +872,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
             let low = self.context.new_cast(None, value, self.cx.ulonglong_type);
             let low = self.context.new_call(None, popcount, &[low]);
             let res = high + low;
-            return self.context.new_bitcast(None, res, result_type);
+            return self.context.new_cast(None, res, result_type);
         }
 
         // First step.
@@ -887,7 +897,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let value = left + right;
 
         if value_type.is_u8(&self.cx) {
-            return self.context.new_bitcast(None, value, result_type);
+            return self.context.new_cast(None, value, result_type);
         }
 
         // Fourth step.
@@ -898,7 +908,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let value = left + right;
 
         if value_type.is_u16(&self.cx) {
-            return self.context.new_bitcast(None, value, result_type);
+            return self.context.new_cast(None, value, result_type);
         }
 
         // Fifth step.
@@ -909,7 +919,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let value = left + right;
 
         if value_type.is_u32(&self.cx) {
-            return self.context.new_bitcast(None, value, result_type);
+            return self.context.new_cast(None, value, result_type);
         }
 
         // Sixth step.
@@ -919,7 +929,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let right = shifted & mask;
         let value = left + right;
 
-        self.context.new_bitcast(None, value, result_type)
+        self.context.new_cast(None, value, result_type)
     }
 
     // Algorithm from: https://blog.regehr.org/archives/1063