[Codegen] fix bugprone return block emission

isuckatcs · Jul 5, 2024 · 015f286 · 015f286
1 parent 4fff0e9
commit 015f286
Show file tree

Hide file tree

Showing 7 changed files with 107 additions and 13 deletions.
diff --git a/src/codegen.cpp b/src/codegen.cpp
@@ -333,14 +333,8 @@ void Codegen::generateBlock(const ResolvedBlock &block) {
       break;
     }
   }
-
-  // FIXME: This should disappear with return optimization.
-  if (const llvm::BasicBlock *bb = builder.GetInsertBlock();
-      bb && bb->empty() && !retBlock->hasNPredecessors(0))
-    builder.CreateUnreachable();
 }
 
-// FIXME: Optimize return stmt emission.
 void Codegen::generateFunctionBody(const ResolvedFunctionDecl &functionDecl) {
   auto *function = module->getFunction(functionDecl.identifier);
   auto *bb = llvm::BasicBlock::Create(context, "", function);
@@ -370,6 +364,7 @@ void Codegen::generateFunctionBody(const ResolvedFunctionDecl &functionDecl) {
     generateBlock(*functionDecl.body);
 
   if (retBlock->hasNPredecessorsOrMore(1)) {
+    builder.CreateBr(retBlock);
     retBlock->insertInto(function);
     builder.SetInsertPoint(retBlock);
   }

diff --git a/test/codegen/condition_empty_merge.al b/test/codegen/condition_empty_merge.al
@@ -23,8 +23,8 @@ fn main(): void {
 // CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
 // CHECK-NEXT: merge:                                            ; preds = <null operand!>, %0
-// CHECK-NEXT:   unreachable
+// CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
-// CHECK-NEXT: return:                                           ; preds = %then
+// CHECK-NEXT: return:                                           ; preds = %merge, %then
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
diff --git a/test/codegen/multiple_return.al b/test/codegen/multiple_return.al
@@ -10,6 +10,6 @@ fn main(): void {
 // CHECK: define void @__builtin_main() {
 // CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
-// CHECK-NEXT: return:                                           ; preds = %0
+// CHECK-NEXT: return:                                           ; preds = <null operand!>, %0
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }
diff --git a/test/codegen/multiple_return_if.al b/test/codegen/multiple_return_if.al
@@ -35,7 +35,7 @@ fn foo(x: number): number {
 // CHECK-NEXT:   store double 5.200000e+00, double* %retval, align 8
 // CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
-// CHECK-NEXT: return:                                           ; preds = %merge5, %then3, %then
+// CHECK-NEXT: return:                                           ; preds = <null operand!>, %merge5, %then3, %then
 // CHECK-NEXT:   %5 = load double, double* %retval, align 8
 // CHECK-NEXT:   ret double %5
 

diff --git a/test/codegen/multiple_return_while.al b/test/codegen/multiple_return_while.al
@@ -38,7 +38,7 @@ fn foo(x: number): number {
 // CHECK-NEXT:   store double 5.000000e+00, double* %retval, align 8
 // CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
-// CHECK-NEXT: return:                                           ; preds = %whileExit, %merge, %then
+// CHECK-NEXT: return:                                           ; preds = <null operand!>, %whileExit, %merge, %then
 // CHECK-NEXT:   %8 = load double, double* %retval, align 8
 // CHECK-NEXT:   ret double %8
 

diff --git a/test/codegen/return.al b/test/codegen/return.al
@@ -0,0 +1,99 @@
+// RUN: compiler %s -llvm-dump 2>&1 | filecheck %s
+// RUN: compiler %s -o return && ./return | ( ! grep ^ )
+fn main(): void {}
+
+fn noInsertPoint(): void {
+    return;
+}
+// CHECK: define void @noInsertPoint() {
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: return:                                           ; preds = <null operand!>, %0
+// CHECK-NEXT:   ret void
+// CHECK-NEXT: }
+
+fn insertPointEmptyBlock(): void {
+    if 1.0 {
+        return;
+    }
+}
+// CHECK: define void @insertPointEmptyBlock() {
+// CHECK-NEXT:   br i1 true, label %then, label %merge
+// CHECK-NEXT: 
+// CHECK-NEXT: then:                                             ; preds = %0
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: merge:                                            ; preds = <null operand!>, %0
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: return:                                           ; preds = %merge, %then
+// CHECK-NEXT:   ret void
+// CHECK-NEXT: }
+
+fn insertPointEmptyBlock2(): void {
+    while 1.0 {
+        return;
+    }
+}
+// CHECK: define void @insertPointEmptyBlock2() {
+// CHECK-NEXT:   br label %whileCond
+// CHECK-NEXT: 
+// CHECK-NEXT: whileCond:                                        ; preds = <null operand!>, %0
+// CHECK-NEXT:   br i1 true, label %whileBody, label %whileExit
+// CHECK-NEXT: 
+// CHECK-NEXT: whileBody:                                        ; preds = %whileCond
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: whileExit:                                        ; preds = %whileCond
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: return:                                           ; preds = %whileExit, %whileBody
+// CHECK-NEXT:   ret void
+// CHECK-NEXT: }
+
+fn insertPointNonEmptyBlock(): void {
+    if 1.0 {
+        return;
+    }
+
+    let x: number = 1.0;
+}
+// CHECK: define void @insertPointNonEmptyBlock() {
+// CHECK-NEXT:   %x = alloca double, align 8
+// CHECK-NEXT:   br i1 true, label %then, label %merge
+// CHECK-NEXT: 
+// CHECK-NEXT: then:                                             ; preds = %0
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: merge:                                            ; preds = <null operand!>, %0
+// CHECK-NEXT:   store double 1.000000e+00, double* %x, align 8
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: return:                                           ; preds = %merge, %then
+// CHECK-NEXT:   ret void
+// CHECK-NEXT: }
+
+fn insertPointNonEmptyBlock2(): void {
+    while 1.0 {
+        return;
+    }
+
+    let x: number = 1.0;
+}
+// CHECK: define void @insertPointNonEmptyBlock2() {
+// CHECK-NEXT:   %x = alloca double, align 8
+// CHECK-NEXT:   br label %whileCond
+// CHECK-NEXT: 
+// CHECK-NEXT: whileCond:                                        ; preds = <null operand!>, %0
+// CHECK-NEXT:   br i1 true, label %whileBody, label %whileExit
+// CHECK-NEXT: 
+// CHECK-NEXT: whileBody:                                        ; preds = %whileCond
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: whileExit:                                        ; preds = %whileCond
+// CHECK-NEXT:   store double 1.000000e+00, double* %x, align 8
+// CHECK-NEXT:   br label %return
+// CHECK-NEXT: 
+// CHECK-NEXT: return:                                           ; preds = %whileExit, %whileBody
+// CHECK-NEXT:   ret void
+// CHECK-NEXT: }
diff --git a/test/codegen/while_empty_exit.al b/test/codegen/while_empty_exit.al
@@ -21,9 +21,9 @@ fn foo(x: number): void {
 // CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
 // CHECK-NEXT: whileExit:                                        ; preds = %whileCond
-// CHECK-NEXT:   unreachable
+// CHECK-NEXT:   br label %return
 // CHECK-NEXT: 
-// CHECK-NEXT: return:                                           ; preds = %whileBody
+// CHECK-NEXT: return:                                           ; preds = %whileExit, %whileBody
 // CHECK-NEXT:   ret void
 // CHECK-NEXT: }