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[CIR] CompoundLiteralExpr for Aggregate types #164172

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Upstream support the CompoundLiteralExpr for Aggregate types

@llvmbot llvmbot added clang Clang issues not falling into any other category ClangIR Anything related to the ClangIR project labels Oct 19, 2025
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llvmbot commented Oct 19, 2025

@llvm/pr-subscribers-clangir

Author: Amr Hesham (AmrDeveloper)

Changes

Upstream support the CompoundLiteralExpr for Aggregate types

Full diff: https://github.com/llvm/llvm-project/pull/164172.diff

3 Files Affected:

  • (modified) clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp (+29-3)
  • (modified) clang/lib/CIR/CodeGen/CIRGenValue.h (+2)
  • (modified) clang/test/CIR/CodeGen/struct.cpp (+19)
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
index 901b937e4e3e7..1a4114d009ffe 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
@@ -180,9 +180,35 @@ class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
     cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitStringLiteral");
   }
   void VisitCompoundLiteralExpr(CompoundLiteralExpr *e) {
-    cgf.cgm.errorNYI(e->getSourceRange(),
-                     "AggExprEmitter: VisitCompoundLiteralExpr");
+    if (dest.isPotentiallyAliased() &&
+        e->getType().isPODType(cgf.getContext())) {
+      cgf.cgm.errorNYI(e->getSourceRange(),
+                       "AggExprEmitter: VisitCompoundLiteralExpr PODType");
+      return;
+    }
+
+    AggValueSlot slot =
+        ensureSlot(cgf.getLoc(e->getSourceRange()), e->getType());
+
+    // Block-scope compound literals are destroyed at the end of the enclosing
+    // scope in C.
+    bool destruct =
+        !cgf.getLangOpts().CPlusPlus && !slot.isExternallyDestructed();
+    if (destruct) {
+      cgf.cgm.errorNYI(
+          e->getSourceRange(),
+          "AggExprEmitter: VisitCompoundLiteralExpr setExternallyDestructed");
+      return;
+    }
+
+    cgf.emitAggExpr(e->getInitializer(), slot);
+
+    if (destruct && e->getType().isDestructedType())
+      cgf.cgm.errorNYI(
+          e->getSourceRange(),
+          "AggExprEmitter: VisitCompoundLiteralExpr destructed type");
   }
+
   void VisitPredefinedExpr(const PredefinedExpr *e) {
     cgf.cgm.errorNYI(e->getSourceRange(),
                      "AggExprEmitter: VisitPredefinedExpr");
@@ -550,7 +576,7 @@ void AggExprEmitter::emitNullInitializationToLValue(mlir::Location loc,
       return;
     }
 
-    cgf.cgm.errorNYI("emitStoreThroughBitfieldLValue");
+    cgf.emitStoreThroughBitfieldLValue(RValue::get(null), lv);
     return;
   }
 
diff --git a/clang/lib/CIR/CodeGen/CIRGenValue.h b/clang/lib/CIR/CodeGen/CIRGenValue.h
index c05142e9853ba..f83a952d26065 100644
--- a/clang/lib/CIR/CodeGen/CIRGenValue.h
+++ b/clang/lib/CIR/CodeGen/CIRGenValue.h
@@ -390,6 +390,8 @@ class AggValueSlot {
 
   IsZeroed_t isZeroed() const { return IsZeroed_t(zeroedFlag); }
 
+  IsAliased_t isPotentiallyAliased() const { return IsAliased_t(aliasedFlag); }
+
   RValue asRValue() const {
     if (isIgnored())
       return RValue::getIgnored();
diff --git a/clang/test/CIR/CodeGen/struct.cpp b/clang/test/CIR/CodeGen/struct.cpp
index 263799f8a5deb..9ec8849602a56 100644
--- a/clang/test/CIR/CodeGen/struct.cpp
+++ b/clang/test/CIR/CodeGen/struct.cpp
@@ -280,3 +280,22 @@ void bin_comma() {
 // OGCG: define{{.*}} void @_Z9bin_commav()
 // OGCG:   %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
 // OGCG:   call void @llvm.memset.p0.i64(ptr align 4 %[[A_ADDR]], i8 0, i64 8, i1 false)
+
+void compound_literal_expr() { CompleteS a = (CompleteS){}; }
+
+// CIR: %[[A_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["a", init]
+// CIR: %[[A_ELEM_0_PTR:.*]] = cir.get_member %[[A_ADDR]][0] {name = "a"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s32i>
+// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s32i
+// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_0_PTR]] : !s32i, !cir.ptr<!s32i>
+// CIR: %[[A_ELEM_1_PTR:.*]] = cir.get_member %[[A_ADDR]][1] {name = "b"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s8i>
+// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s8i
+// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_1_PTR]] : !s8i, !cir.ptr<!s8i>
+
+// LLVM: %[[A_ADDR:.*]] = alloca %struct.CompleteS, i64 1, align 4
+// LLVM: %[[A_ELEM_0_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 0
+// LLVM: store i32 0, ptr %[[A_ELEM_0_PTR]], align 4
+// LLVM: %[[A_ELEM_1_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 1
+// LLVM: store i8 0, ptr %[[A_ELEM_1_PTR]], align 4
+
+// OGCG: %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
+// OGCG: call void @llvm.memset.p0.i64(ptr align 4 %[[A_ADDR]], i8 0, i64 8, i1 false)

@llvmbot
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llvmbot commented Oct 19, 2025

@llvm/pr-subscribers-clang

Author: Amr Hesham (AmrDeveloper)

Changes

Upstream support the CompoundLiteralExpr for Aggregate types

Full diff: https://github.com/llvm/llvm-project/pull/164172.diff

3 Files Affected:

  • (modified) clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp (+29-3)
  • (modified) clang/lib/CIR/CodeGen/CIRGenValue.h (+2)
  • (modified) clang/test/CIR/CodeGen/struct.cpp (+19)
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
index 901b937e4e3e7..1a4114d009ffe 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
@@ -180,9 +180,35 @@ class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
     cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitStringLiteral");
   }
   void VisitCompoundLiteralExpr(CompoundLiteralExpr *e) {
-    cgf.cgm.errorNYI(e->getSourceRange(),
-                     "AggExprEmitter: VisitCompoundLiteralExpr");
+    if (dest.isPotentiallyAliased() &&
+        e->getType().isPODType(cgf.getContext())) {
+      cgf.cgm.errorNYI(e->getSourceRange(),
+                       "AggExprEmitter: VisitCompoundLiteralExpr PODType");
+      return;
+    }
+
+    AggValueSlot slot =
+        ensureSlot(cgf.getLoc(e->getSourceRange()), e->getType());
+
+    // Block-scope compound literals are destroyed at the end of the enclosing
+    // scope in C.
+    bool destruct =
+        !cgf.getLangOpts().CPlusPlus && !slot.isExternallyDestructed();
+    if (destruct) {
+      cgf.cgm.errorNYI(
+          e->getSourceRange(),
+          "AggExprEmitter: VisitCompoundLiteralExpr setExternallyDestructed");
+      return;
+    }
+
+    cgf.emitAggExpr(e->getInitializer(), slot);
+
+    if (destruct && e->getType().isDestructedType())
+      cgf.cgm.errorNYI(
+          e->getSourceRange(),
+          "AggExprEmitter: VisitCompoundLiteralExpr destructed type");
   }
+
   void VisitPredefinedExpr(const PredefinedExpr *e) {
     cgf.cgm.errorNYI(e->getSourceRange(),
                      "AggExprEmitter: VisitPredefinedExpr");
@@ -550,7 +576,7 @@ void AggExprEmitter::emitNullInitializationToLValue(mlir::Location loc,
       return;
     }
 
-    cgf.cgm.errorNYI("emitStoreThroughBitfieldLValue");
+    cgf.emitStoreThroughBitfieldLValue(RValue::get(null), lv);
     return;
   }
 
diff --git a/clang/lib/CIR/CodeGen/CIRGenValue.h b/clang/lib/CIR/CodeGen/CIRGenValue.h
index c05142e9853ba..f83a952d26065 100644
--- a/clang/lib/CIR/CodeGen/CIRGenValue.h
+++ b/clang/lib/CIR/CodeGen/CIRGenValue.h
@@ -390,6 +390,8 @@ class AggValueSlot {
 
   IsZeroed_t isZeroed() const { return IsZeroed_t(zeroedFlag); }
 
+  IsAliased_t isPotentiallyAliased() const { return IsAliased_t(aliasedFlag); }
+
   RValue asRValue() const {
     if (isIgnored())
       return RValue::getIgnored();
diff --git a/clang/test/CIR/CodeGen/struct.cpp b/clang/test/CIR/CodeGen/struct.cpp
index 263799f8a5deb..9ec8849602a56 100644
--- a/clang/test/CIR/CodeGen/struct.cpp
+++ b/clang/test/CIR/CodeGen/struct.cpp
@@ -280,3 +280,22 @@ void bin_comma() {
 // OGCG: define{{.*}} void @_Z9bin_commav()
 // OGCG:   %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
 // OGCG:   call void @llvm.memset.p0.i64(ptr align 4 %[[A_ADDR]], i8 0, i64 8, i1 false)
+
+void compound_literal_expr() { CompleteS a = (CompleteS){}; }
+
+// CIR: %[[A_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["a", init]
+// CIR: %[[A_ELEM_0_PTR:.*]] = cir.get_member %[[A_ADDR]][0] {name = "a"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s32i>
+// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s32i
+// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_0_PTR]] : !s32i, !cir.ptr<!s32i>
+// CIR: %[[A_ELEM_1_PTR:.*]] = cir.get_member %[[A_ADDR]][1] {name = "b"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s8i>
+// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s8i
+// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_1_PTR]] : !s8i, !cir.ptr<!s8i>
+
+// LLVM: %[[A_ADDR:.*]] = alloca %struct.CompleteS, i64 1, align 4
+// LLVM: %[[A_ELEM_0_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 0
+// LLVM: store i32 0, ptr %[[A_ELEM_0_PTR]], align 4
+// LLVM: %[[A_ELEM_1_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 1
+// LLVM: store i8 0, ptr %[[A_ELEM_1_PTR]], align 4
+
+// OGCG: %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
+// OGCG: call void @llvm.memset.p0.i64(ptr align 4 %[[A_ADDR]], i8 0, i64 8, i1 false)

andykaylor
andykaylor reviewed Oct 20, 2025
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clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp Outdated
}

cgf.cgm.errorNYI("emitStoreThroughBitfieldLValue");
cgf.emitStoreThroughBitfieldLValue(RValue::get(null), lv);
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OGCG implements this as:

    // For non-aggregates, we can store the appropriate null constant.
    llvm::Value *null = CGF.CGM.EmitNullConstant(type);
    // Note that the following is not equivalent to
    // EmitStoreThroughBitfieldLValue for ARC types.
    if (lv.isBitField()) {
      CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
    } else {
      assert(lv.isSimple());
      CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
    }

We should probably follow that structure rather than assume it's a bitfield if it's not simple.

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Also, you don't have a test that covers this.

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I removed the bit field for now because actually i need only the other part for a follow up PR :D

clang/test/CIR/CodeGen/struct.cpp
// LLVM: %[[A_ELEM_0_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 0
// LLVM: store i32 0, ptr %[[A_ELEM_0_PTR]], align 4
// LLVM: %[[A_ELEM_1_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 1
// LLVM: store i8 0, ptr %[[A_ELEM_1_PTR]], align 4
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Unlike OGCG, this doesn't zero-initialize the padding. Is that OK? Does the fact that we're setting each member prevent the optimizer from turning this into a memset?

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I added a TODO for now, and later we can revisit it

andykaylor
andykaylor approved these changes Oct 20, 2025
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lgtm

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@andykaylor andykaylor andykaylor approved these changes

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@AmrDeveloper @llvmbot @andykaylor