Rollup merge of #93261 - bjorn3:cg_ssa_refactor6, r=cjgillot

Some unwinding related cg_ssa cleanups

These should make it a bit easier for alternative codegen backends to implement unwinding.

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1256,7 +1256,11 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         aggregate_value
     }
 
-    fn landing_pad(&mut self, _ty: Type<'gcc>, _pers_fn: RValue<'gcc>, _num_clauses: usize) -> RValue<'gcc> {
+    fn set_personality_fn(&mut self, _personality: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn cleanup_landing_pad(&mut self, _ty: Type<'gcc>, _pers_fn: RValue<'gcc>) -> RValue<'gcc> {
         let field1 = self.context.new_field(None, self.u8_type, "landing_pad_field_1");
         let field2 = self.context.new_field(None, self.i32_type, "landing_pad_field_1");
         let struct_type = self.context.new_struct_type(None, "landing_pad", &[field1, field2]);
@@ -1267,38 +1271,31 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         // rustc_codegen_ssa now calls the unwinding builder methods even on panic=abort.
     }
 
-    fn set_cleanup(&mut self, _landing_pad: RValue<'gcc>) {
-        // TODO(antoyo)
-    }
-
-    fn resume(&mut self, _exn: RValue<'gcc>) -> RValue<'gcc> {
+    fn resume(&mut self, _exn: RValue<'gcc>) {
         unimplemented!();
     }
 
     fn cleanup_pad(&mut self, _parent: Option<RValue<'gcc>>, _args: &[RValue<'gcc>]) -> Funclet {
         unimplemented!();
     }
 
-    fn cleanup_ret(&mut self, _funclet: &Funclet, _unwind: Option<Block<'gcc>>) -> RValue<'gcc> {
+    fn cleanup_ret(&mut self, _funclet: &Funclet, _unwind: Option<Block<'gcc>>) {
         unimplemented!();
     }
 
     fn catch_pad(&mut self, _parent: RValue<'gcc>, _args: &[RValue<'gcc>]) -> Funclet {
         unimplemented!();
     }
 
-    fn catch_switch(&mut self, _parent: Option<RValue<'gcc>>, _unwind: Option<Block<'gcc>>, _num_handlers: usize) -> RValue<'gcc> {
+    fn catch_switch(
+        &mut self,
+        _parent: Option<RValue<'gcc>>,
+        _unwind: Option<Block<'gcc>>,
+        _handlers: &[Block<'gcc>],
+    ) -> RValue<'gcc> {
         unimplemented!();
     }
 
-    fn add_handler(&mut self, _catch_switch: RValue<'gcc>, _handler: Block<'gcc>) {
-        unimplemented!();
-    }
-
-    fn set_personality_fn(&mut self, _personality: RValue<'gcc>) {
-        // TODO(antoyo)
-    }
-
     // Atomic Operations
     fn atomic_cmpxchg(&mut self, dst: RValue<'gcc>, cmp: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
         let expected = self.current_func().new_local(None, cmp.get_type(), "expected");

compiler/rustc_codegen_llvm/src/builder.rs

@@ -956,29 +956,24 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unsafe { llvm::LLVMBuildInsertValue(self.llbuilder, agg_val, elt, idx as c_uint, UNNAMED) }
     }
 
-    fn landing_pad(
-        &mut self,
-        ty: &'ll Type,
-        pers_fn: &'ll Value,
-        num_clauses: usize,
-    ) -> &'ll Value {
-        // Use LLVMSetPersonalityFn to set the personality. It supports arbitrary Consts while,
-        // LLVMBuildLandingPad requires the argument to be a Function (as of LLVM 12). The
-        // personality lives on the parent function anyway.
-        self.set_personality_fn(pers_fn);
+    fn set_personality_fn(&mut self, personality: &'ll Value) {
         unsafe {
-            llvm::LLVMBuildLandingPad(self.llbuilder, ty, None, num_clauses as c_uint, UNNAMED)
+            llvm::LLVMSetPersonalityFn(self.llfn(), personality);
         }
     }
 
-    fn set_cleanup(&mut self, landing_pad: &'ll Value) {
+    fn cleanup_landing_pad(&mut self, ty: &'ll Type, pers_fn: &'ll Value) -> &'ll Value {
+        let landing_pad = self.landing_pad(ty, pers_fn, 1 /* FIXME should this be 0? */);
         unsafe {
             llvm::LLVMSetCleanup(landing_pad, llvm::True);
         }
+        landing_pad
     }
 
-    fn resume(&mut self, exn: &'ll Value) -> &'ll Value {
-        unsafe { llvm::LLVMBuildResume(self.llbuilder, exn) }
+    fn resume(&mut self, exn: &'ll Value) {
+        unsafe {
+            llvm::LLVMBuildResume(self.llbuilder, exn);
+        }
     }
 
     fn cleanup_pad(&mut self, parent: Option<&'ll Value>, args: &[&'ll Value]) -> Funclet<'ll> {
@@ -995,14 +990,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         Funclet::new(ret.expect("LLVM does not have support for cleanuppad"))
     }
 
-    fn cleanup_ret(
-        &mut self,
-        funclet: &Funclet<'ll>,
-        unwind: Option<&'ll BasicBlock>,
-    ) -> &'ll Value {
-        let ret =
-            unsafe { llvm::LLVMRustBuildCleanupRet(self.llbuilder, funclet.cleanuppad(), unwind) };
-        ret.expect("LLVM does not have support for cleanupret")
+    fn cleanup_ret(&mut self, funclet: &Funclet<'ll>, unwind: Option<&'ll BasicBlock>) {
+        unsafe {
+            llvm::LLVMRustBuildCleanupRet(self.llbuilder, funclet.cleanuppad(), unwind)
+                .expect("LLVM does not have support for cleanupret");
+        }
     }
 
     fn catch_pad(&mut self, parent: &'ll Value, args: &[&'ll Value]) -> Funclet<'ll> {
@@ -1023,31 +1015,25 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         parent: Option<&'ll Value>,
         unwind: Option<&'ll BasicBlock>,
-        num_handlers: usize,
+        handlers: &[&'ll BasicBlock],
     ) -> &'ll Value {
         let name = cstr!("catchswitch");
         let ret = unsafe {
             llvm::LLVMRustBuildCatchSwitch(
                 self.llbuilder,
                 parent,
                 unwind,
-                num_handlers as c_uint,
+                handlers.len() as c_uint,
                 name.as_ptr(),
             )
         };
-        ret.expect("LLVM does not have support for catchswitch")
-    }
-
-    fn add_handler(&mut self, catch_switch: &'ll Value, handler: &'ll BasicBlock) {
-        unsafe {
-            llvm::LLVMRustAddHandler(catch_switch, handler);
-        }
-    }
-
-    fn set_personality_fn(&mut self, personality: &'ll Value) {
-        unsafe {
-            llvm::LLVMSetPersonalityFn(self.llfn(), personality);
+        let ret = ret.expect("LLVM does not have support for catchswitch");
+        for handler in handlers {
+            unsafe {
+                llvm::LLVMRustAddHandler(ret, handler);
+            }
         }
+        ret
     }
 
     // Atomic Operations
@@ -1478,4 +1464,19 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
             None
         }
     }
+
+    pub(crate) fn landing_pad(
+        &mut self,
+        ty: &'ll Type,
+        pers_fn: &'ll Value,
+        num_clauses: usize,
+    ) -> &'ll Value {
+        // Use LLVMSetPersonalityFn to set the personality. It supports arbitrary Consts while,
+        // LLVMBuildLandingPad requires the argument to be a Function (as of LLVM 12). The
+        // personality lives on the parent function anyway.
+        self.set_personality_fn(pers_fn);
+        unsafe {
+            llvm::LLVMBuildLandingPad(self.llbuilder, ty, None, num_clauses as c_uint, UNNAMED)
+        }
+    }
 }

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -525,9 +525,8 @@ fn codegen_msvc_try<'ll>(
 
         normal.ret(bx.const_i32(0));
 
-        let cs = catchswitch.catch_switch(None, None, 2);
-        catchswitch.add_handler(cs, catchpad_rust.llbb());
-        catchswitch.add_handler(cs, catchpad_foreign.llbb());
+        let cs =
+            catchswitch.catch_switch(None, None, &[catchpad_rust.llbb(), catchpad_foreign.llbb()]);
 
         // We can't use the TypeDescriptor defined in libpanic_unwind because it
         // might be in another DLL and the SEH encoding only supports specifying

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1346,8 +1346,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     let mut cp_bx = self.new_block(&format!("cp_funclet{:?}", bb));
                     ret_llbb = cs_bx.llbb();
 
-                    let cs = cs_bx.catch_switch(None, None, 1);
-                    cs_bx.add_handler(cs, cp_bx.llbb());
+                    let cs = cs_bx.catch_switch(None, None, &[cp_bx.llbb()]);
 
                     // The "null" here is actually a RTTI type descriptor for the
                     // C++ personality function, but `catch (...)` has no type so
@@ -1374,8 +1373,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
             let llpersonality = self.cx.eh_personality();
             let llretty = self.landing_pad_type();
-            let lp = bx.landing_pad(llretty, llpersonality, 1);
-            bx.set_cleanup(lp);
+            let lp = bx.cleanup_landing_pad(llretty, llpersonality);
 
             let slot = self.get_personality_slot(&mut bx);
             slot.storage_live(&mut bx);

compiler/rustc_codegen_ssa/src/traits/builder.rs

@@ -421,29 +421,22 @@ pub trait BuilderMethods<'a, 'tcx>:
     fn extract_value(&mut self, agg_val: Self::Value, idx: u64) -> Self::Value;
     fn insert_value(&mut self, agg_val: Self::Value, elt: Self::Value, idx: u64) -> Self::Value;
 
-    fn landing_pad(
-        &mut self,
-        ty: Self::Type,
-        pers_fn: Self::Value,
-        num_clauses: usize,
-    ) -> Self::Value;
-    fn set_cleanup(&mut self, landing_pad: Self::Value);
-    fn resume(&mut self, exn: Self::Value) -> Self::Value;
+    fn set_personality_fn(&mut self, personality: Self::Value);
+
+    // These are used by everyone except msvc
+    fn cleanup_landing_pad(&mut self, ty: Self::Type, pers_fn: Self::Value) -> Self::Value;
+    fn resume(&mut self, exn: Self::Value);
+
+    // These are used only by msvc
     fn cleanup_pad(&mut self, parent: Option<Self::Value>, args: &[Self::Value]) -> Self::Funclet;
-    fn cleanup_ret(
-        &mut self,
-        funclet: &Self::Funclet,
-        unwind: Option<Self::BasicBlock>,
-    ) -> Self::Value;
+    fn cleanup_ret(&mut self, funclet: &Self::Funclet, unwind: Option<Self::BasicBlock>);
     fn catch_pad(&mut self, parent: Self::Value, args: &[Self::Value]) -> Self::Funclet;
     fn catch_switch(
         &mut self,
         parent: Option<Self::Value>,
         unwind: Option<Self::BasicBlock>,
-        num_handlers: usize,
+        handlers: &[Self::BasicBlock],
     ) -> Self::Value;
-    fn add_handler(&mut self, catch_switch: Self::Value, handler: Self::BasicBlock);
-    fn set_personality_fn(&mut self, personality: Self::Value);
 
     fn atomic_cmpxchg(
         &mut self,