[clang] [clang][CodeGen] Fix crash on if/switch init-statement ending in noreturn (PR #201047)

[via cfe-commits]

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: lijinpei-amd

<details>
<summary>Changes</summary>

EmitStmt may `ClearInsertionPoint()` to mark dead code, EmitDecl is not prepared to handle it. Fix by `EnsureInsertPoint()` in transition from EmitStmt to EmitDecl. If/Switch body may contain a label which makes them not dead.

Fixes #<!-- -->115514.

---
Full diff: https://github.com/llvm/llvm-project/pull/201047.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGStmt.cpp (+12-2) 
- (added) clang/test/CodeGenCXX/noreturn-init-stmt.cpp (+32) 


``````````diff
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 4f847a5879dc6..1b108d9ceea7b 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -885,9 +885,14 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
   LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());
   ApplyDebugLocation DL(*this, S.getCond());
 
-  if (S.getInit())
+  if (S.getInit()) {
     EmitStmt(S.getInit());
 
+    // The init statement may have cleared the insertion point (e.g. it ended in
+    // a 'noreturn' call); the condition emitted below needs a valid one.
+    EnsureInsertPoint();
+  }
+
   if (S.getConditionVariable())
     EmitDecl(*S.getConditionVariable());
 
@@ -2374,9 +2379,14 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
 
   RunCleanupsScope ConditionScope(*this);
 
-  if (S.getInit())
+  if (S.getInit()) {
     EmitStmt(S.getInit());
 
+    // The init statement may have cleared the insertion point (e.g. it ended in
+    // a 'noreturn' call); the condition emitted below needs a valid one.
+    EnsureInsertPoint();
+  }
+
   if (S.getConditionVariable())
     EmitDecl(*S.getConditionVariable());
   llvm::Value *CondV = EmitScalarExpr(S.getCond());
diff --git a/clang/test/CodeGenCXX/noreturn-init-stmt.cpp b/clang/test/CodeGenCXX/noreturn-init-stmt.cpp
new file mode 100644
index 0000000000000..8ea66f0a2344b
--- /dev/null
+++ b/clang/test/CodeGenCXX/noreturn-init-stmt.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+struct T {
+  ~T();
+};
+[[noreturn]] void die();
+bool check(const T &);
+int pick(const T &);
+
+// CHECK-LABEL: define {{.*}} @_Z4testb(
+int test(bool cond) {
+  if (cond)
+    goto label;
+  if (die(); check(T())) {
+  label:
+    return 1;
+  }
+  return 0;
+}
+
+// CHECK-LABEL: define {{.*}} @_Z11test_switchb(
+int test_switch(bool cond) {
+  if (cond)
+    goto label;
+  switch (die(); pick(T())) {
+  case 1:
+    return 1;
+  label:
+    return 2;
+  }
+  return 0;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/201047