[clang] [CIR] Upstream SizeOf for VariableArrayType (PR #169993)
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cfe-commits at lists.llvm.org
Sat Nov 29 04:43:17 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Amr Hesham (AmrDeveloper)
<details>
<summary>Changes</summary>
Upstream SizeOf support for VariableArrayType
---
Full diff: https://github.com/llvm/llvm-project/pull/169993.diff
2 Files Affected:
- (modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+17-13)
- (added) clang/test/CIR/CodeGen/size-of-vla.cpp (+156)
``````````diff
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index a8c2061ddbd6c..c8b70c7ba46ae 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -2344,25 +2344,29 @@ mlir::Value ScalarExprEmitter::VisitUnaryExprOrTypeTraitExpr(
} else {
// C99 6.5.3.4p2: If the argument is an expression of type
// VLA, it is evaluated.
- cgf.getCIRGenModule().errorNYI(
- e->getSourceRange(),
- "sizeof operator for VariableArrayType & evaluateExtent "
- "ignoredExpr",
- e->getStmtClassName());
- return {};
+ cgf.emitIgnoredExpr(e->getArgumentExpr());
}
// For _Countof, we just want to return the size of a single dimension.
if (kind == UETT_CountOf)
return cgf.getVLAElements1D(vat).numElts;
- cgf.getCIRGenModule().errorNYI(
- e->getSourceRange(),
- "sizeof operator for VariableArrayType & evaluateExtent",
- e->getStmtClassName());
- return builder.getConstant(
- loc, cir::IntAttr::get(cgf.cgm.uInt64Ty,
- -llvm::APSInt(llvm::APInt(64, 1), true)));
+ // For sizeof and __datasizeof, we need to scale the number of elements
+ // by the size of the array element type.
+ auto vlaSize = cgf.getVLASize(vat);
+ mlir::Value numElts = vlaSize.numElts;
+
+ // Scale the number of non-VLA elements by the non-VLA element size.
+ CharUnits eltSize = cgf.getContext().getTypeSizeInChars(vlaSize.type);
+ if (!eltSize.isOne()) {
+ mlir::Location loc = cgf.getLoc(e->getSourceRange());
+ mlir::Value eltSizeValue =
+ builder.getConstAPInt(numElts.getLoc(), numElts.getType(),
+ cgf.cgm.getSize(eltSize).getValue());
+ return builder.createMul(loc, eltSizeValue, numElts);
+ }
+
+ return numElts;
}
}
} else if (e->getKind() == UETT_OpenMPRequiredSimdAlign) {
diff --git a/clang/test/CIR/CodeGen/size-of-vla.cpp b/clang/test/CIR/CodeGen/size-of-vla.cpp
new file mode 100644
index 0000000000000..f87ede006643b
--- /dev/null
+++ b/clang/test/CIR/CodeGen/size-of-vla.cpp
@@ -0,0 +1,156 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+void vla_type_with_element_type_of_size_1() {
+ unsigned long n = 10ul;
+ unsigned long size = sizeof(bool[n]);
+}
+
+// CIR: %[[N_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["n", init]
+// CIR: %[[SIZE_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["size", init]
+// CIR: %[[CONST_10:.*]] = cir.const #cir.int<10> : !u64i
+// CIR: cir.store {{.*}} %[[CONST_10]], %[[N_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[TMP_N:.*]] = cir.load {{.*}} %[[N_ADDR]] : !cir.ptr<!u64i>, !u64i
+// CIR: cir.store {{.*}} %[[TMP_N]], %[[SIZE_ADDR]] : !u64i, !cir.ptr<!u64i>
+
+// LLVM: %[[N_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SIZE_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: store i64 10, ptr %[[N_ADDR]], align 8
+// LLVM: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// LLVM: store i64 %[[TMP_N]], ptr %[[SIZE_ADDR]], align 8
+
+// OGCG: %[[N_ADDR:.*]] = alloca i64, align 8
+// OGCG: %[[SIZE_ADDR:.*]] = alloca i64, align 8
+// OGCG: store i64 10, ptr %[[N_ADDR]], align 8
+// OGCG: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// OGCG: store i64 %[[TMP_N]], ptr %[[SIZE_ADDR]], align 8
+
+void vla_type_with_element_type_int() {
+ unsigned long n = 10ul;
+ unsigned long size = sizeof(int[n]);
+}
+
+// CIR: %[[N_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["n", init]
+// CIR: %[[SIZE_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["size", init]
+// CIR: %[[CONST_10:.*]] = cir.const #cir.int<10> : !u64i
+// CIR: cir.store {{.*}} %[[CONST_10]], %[[N_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %3 = cir.load {{.*}} %[[N_ADDR]] : !cir.ptr<!u64i>, !u64i
+// CIR: %[[CONST_4:.*]] = cir.const #cir.int<4> : !u64i
+// CIR: %[[SIZE:.*]] = cir.binop(mul, %[[CONST_4]], %3) : !u64i
+// CIR: cir.store {{.*}} %[[SIZE]], %[[SIZE_ADDR]] : !u64i, !cir.ptr<!u64i>
+
+// LLVM: %[[N_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SIZE_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: store i64 10, ptr %[[N_ADDR]], align 8
+// LLVM: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// LLVM: %[[SIZE:.*]] = mul i64 4, %[[TMP_N]]
+// LLVM: store i64 %[[SIZE]], ptr %[[SIZE_ADDR]], align 8
+
+// OGCG: %[[N_ADDR:.*]] = alloca i64, align 8
+// OGCG: %[[SIZE_ADDR:.*]] = alloca i64, align 8
+// OGCG: store i64 10, ptr %[[N_ADDR]], align 8
+// OGCG: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// OGCG: %[[SIZE:.*]] = mul nuw i64 4, %[[TMP_N]]
+// OGCG: store i64 %[[SIZE]], ptr %[[SIZE_ADDR]], align 8
+
+void vla_expr_element_type_of_size_1() {
+ unsigned long n = 10ul;
+ bool arr[n];
+ unsigned long size = sizeof(arr);
+}
+
+// CIR: %[[N_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["n", init]
+// CIR: %[[SAVED_STACK_ADDR:.*]] = cir.alloca !cir.ptr<!u8i>, !cir.ptr<!cir.ptr<!u8i>>, ["saved_stack"]
+// CIR: %[[CONST_10:.*]] = cir.const #cir.int<10> : !u64i
+// CIR: cir.store {{.*}} %[[CONST_10]], %[[N_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[TMP_N:.*]] = cir.load {{.*}} %[[N_ADDR]] : !cir.ptr<!u64i>, !u64i
+// CIR: %[[STACK_SAVE:.*]] = cir.stacksave : !cir.ptr<!u8i>
+// CIR: cir.store {{.*}} %[[STACK_SAVE]], %[[SAVED_STACK_ADDR]] : !cir.ptr<!u8i>, !cir.ptr<!cir.ptr<!u8i>>
+// CIR: %[[ARR_ADDR:.*]] = cir.alloca !cir.bool, !cir.ptr<!cir.bool>, %[[TMP_N]] : !u64i, ["arr"]
+// CIR: %[[SIZE_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["size", init]
+// CIR: cir.store {{.*}} %[[TMP_N]], %[[SIZE_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[TMP_SAVED_STACK:.*]] = cir.load {{.*}} %[[SAVED_STACK_ADDR]] : !cir.ptr<!cir.ptr<!u8i>>, !cir.ptr<!u8i>
+// CIR: cir.stackrestore %[[TMP_SAVED_STACK]] : !cir.ptr<!u8i>
+
+// LLVM: %[[N_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SAVED_STACK_ADDR:.*]] = alloca ptr, i64 1, align 8
+// LLVM: store i64 10, ptr %[[N_ADDR]], align 8
+// LLVM: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// LLVM: %[[STACK_SAVE:.*]] = call ptr @llvm.stacksave.p0()
+// LLVM: store ptr %[[STACK_SAVE]], ptr %[[SAVED_STACK_ADDR]], align 8
+// LLVM: %[[ARR_ADDR:.*]] = alloca i8, i64 %[[TMP_N]], align 16
+// LLVM: %[[SIZE_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: store i64 %[[TMP_N]], ptr %[[SIZE_ADDR]], align 8
+// LLVM: %[[TMP_SAVED_STACK:.*]] = load ptr, ptr %[[SAVED_STACK_ADDR]], align 8
+// LLVM: call void @llvm.stackrestore.p0(ptr %[[TMP_SAVED_STACK]])
+
+// Note: VLA_EXPR0 below is emitted to capture debug info.
+
+// OGCG: %[[N_ADDR:.*]] = alloca i64, align 8
+// OGCG: %[[SAVED_STACK_ADDR:.*]] = alloca ptr, align 8
+// OGCG: %[[VLA_EXPR0:.*]] = alloca i64, align 8
+// OGCG: %[[SIZE_ADDR:.*]] = alloca i64, align 8
+// OGCG: store i64 10, ptr %[[N_ADDR]], align 8
+// OGCG: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// OGCG: %[[STACK_SAVE:.*]] = call ptr @llvm.stacksave.p0()
+// OGCG: store ptr %[[STACK_SAVE]], ptr %[[SAVED_STACK_ADDR]], align 8
+// OGCG: %[[ARR_ADDR:.*]] = alloca i8, i64 %[[TMP_N]], align 16
+// OGCG: store i64 %[[TMP_N]], ptr %[[VLA_EXPR0]], align 8
+// OGCG: store i64 %[[TMP_N]], ptr %[[SIZE_ADDR]], align 8
+// OGCG: %[[TMP_SAVED_STACK:.*]] = load ptr, ptr %[[SAVED_STACK_ADDR]], align 8
+// OGCG: call void @llvm.stackrestore.p0(ptr %[[TMP_SAVED_STACK]])
+
+void vla_expr_element_type_int() {
+ unsigned long n = 10ul;
+ int arr[n];
+ unsigned long size = sizeof(arr);
+}
+
+// CIR: %[[N_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["n", init]
+// CIR: %[[SAVED_STACK_ADDR:.*]] = cir.alloca !cir.ptr<!u8i>, !cir.ptr<!cir.ptr<!u8i>>, ["saved_stack"]
+// CIR: %[[CONST_10:.*]] = cir.const #cir.int<10> : !u64i
+// CIR: cir.store {{.*}} %[[CONST_10]], %[[N_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[TMP_N:.*]] = cir.load {{.*}} %[[N_ADDR]] : !cir.ptr<!u64i>, !u64i
+// CIR: %[[STACK_SAVE:.*]] = cir.stacksave : !cir.ptr<!u8i>
+// CIR: cir.store {{.*}} %[[STACK_SAVE]], %[[SAVED_STACK_ADDR]] : !cir.ptr<!u8i>, !cir.ptr<!cir.ptr<!u8i>>
+// CIR: %[[ARR_ADDR:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, %[[TMP_N]] : !u64i, ["arr"]
+// CIR: %[[SIZE_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["size", init]
+// CIR: %[[CONST_4:.*]] = cir.const #cir.int<4> : !u64i
+// CIR: %[[SIZE:.*]] = cir.binop(mul, %[[CONST_4]], %[[TMP_N]]) : !u64i
+// CIR: cir.store {{.*}} %[[SIZE]], %[[SIZE_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[TMP_SAVED_STACK:.*]] = cir.load {{.*}} %[[SAVED_STACK_ADDR]] : !cir.ptr<!cir.ptr<!u8i>>, !cir.ptr<!u8i>
+// CIR: cir.stackrestore %[[TMP_SAVED_STACK]] : !cir.ptr<!u8i>
+
+// LLVM: %[[N_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SAVED_STACK_ADDR:.*]] = alloca ptr, i64 1, align 8
+// LLVM: store i64 10, ptr %[[N_ADDR]], align 8
+// LLVM: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// LLVM: %[[STACK_SAVE:.*]] = call ptr @llvm.stacksave.p0()
+// LLVM: store ptr %[[STACK_SAVE]], ptr %[[SAVED_STACK_ADDR]], align 8
+// LLVM: %[[ARR_ADDR:.*]] = alloca i32, i64 %[[TMP_N]], align 16
+// LLVM: %[[SIZE_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SIZE:.*]] = mul i64 4, %[[TMP_N]]
+// LLVM: store i64 %[[SIZE]], ptr %[[SIZE_ADDR]], align 8
+// LLVM: %[[TMP_SAVED_STACK:.*]] = load ptr, ptr %[[SAVED_STACK_ADDR]], align 8
+// LLVM: call void @llvm.stackrestore.p0(ptr %[[TMP_SAVED_STACK]])
+
+// Note: VLA_EXPR0 below is emitted to capture debug info.
+
+// OGCG: %[[N_ADDR:.*]] = alloca i64, align 8
+// OGCG: %[[SAVED_STACK_ADDR:.*]] = alloca ptr, align 8
+// OGCG: %[[VLA_EXPR0:.*]] = alloca i64, align 8
+// OGCG: %[[SIZE_ADDR:.*]] = alloca i64, align 8
+// OGCG: store i64 10, ptr %[[N_ADDR]], align 8
+// OGCG: %[[TMP_N:.*]] = load i64, ptr %[[N_ADDR]], align 8
+// OGCG: %[[STACK_SAVE:.*]] = call ptr @llvm.stacksave.p0()
+// OGCG: store ptr %[[STACK_SAVE]], ptr %[[SAVED_STACK_ADDR]], align 8
+// OGCG: %[[ARR_ADDR:.*]] = alloca i32, i64 %[[TMP_N]], align 16
+// OGCG: store i64 %[[TMP_N]], ptr %[[VLA_EXPR0]], align 8
+// OGCG: %[[SIZE:.*]] = mul nuw i64 4, %[[TMP_N]]
+// OGCG: store i64 %[[SIZE]], ptr %[[SIZE_ADDR]], align 8
+// OGCG: %[[TMP_SAVED_STACK:.*]] = load ptr, ptr %[[SAVED_STACK_ADDR]], align 8
+// OGCG: call void @llvm.stackrestore.p0(ptr %[[TMP_SAVED_STACK]])
``````````
</details>
https://github.com/llvm/llvm-project/pull/169993
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