[PATCH] D78098: [CGExprAgg] Fix infinite loop in `findPeephole`

[Ehud Katz via Phabricator via cfe-commits]

ekatz updated this revision to Diff 257299.
ekatz added a comment.
Herald added a subscriber: jfb.

Added test.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D78098/new/

https://reviews.llvm.org/D78098

Files:
  clang/lib/CodeGen/CGExprAgg.cpp
  clang/test/CodeGen/atomic-struct-bug.cpp


Index: clang/test/CodeGen/atomic-struct-bug.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGen/atomic-struct-bug.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+// PR45476
+
+// This test used to get into an infinite loop,
+// which, in turn, caused clang to never finish execution.
+
+struct s3 {
+  char a, b, c;
+};
+
+_Atomic struct s3 a;
+
+extern "C" void foo() {
+  // CHECK-LABEL: @foo
+  // CHECK: store atomic i32
+
+  a = s3{1, 2, 3};
+}
+
Index: clang/lib/CodeGen/CGExprAgg.cpp
===================================================================
--- clang/lib/CodeGen/CGExprAgg.cpp
+++ clang/lib/CodeGen/CGExprAgg.cpp
@@ -678,16 +678,16 @@
 /// Attempt to look through various unimportant expressions to find a
 /// cast of the given kind.
 static Expr *findPeephole(Expr *op, CastKind kind) {
-  while (true) {
-    op = op->IgnoreParens();
-    if (CastExpr *castE = dyn_cast<CastExpr>(op)) {
-      if (castE->getCastKind() == kind)
-        return castE->getSubExpr();
-      if (castE->getCastKind() == CK_NoOp)
-        continue;
-    }
-    return nullptr;
+  while (CastExpr *castE = dyn_cast<CastExpr>(op->IgnoreParens())) {
+    if (castE->getCastKind() == kind)
+      return castE->getSubExpr();
+
+    if (castE->getCastKind() != CK_NoOp || castE == op)
+      break;
+
+    op = castE;
   }
+  return nullptr;
 }
 
 void AggExprEmitter::VisitCastExpr(CastExpr *E) {


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