[CIR] Upstream basic support for sizeof and alignof

[AmrDeveloper]

This change adds the essential support for sizeof and alignof operators

• Support for VariableArrayType can be added after closing [CIR] Upstream support for array types #130197

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clangir

Author: Amr Hesham (AmrDeveloper)

Changes

This change adds the essential support for sizeof and alignof operators

• Support for VariableArrayType can be added after closing #130197

---

Full diff: https://github.com/llvm/llvm-project/pull/130847.diff

3 Files Affected:

• (modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+26)
• (added) clang/test/CIR/CodeGen/unary-expr-or-type-trait.cpp (+35)
• (added) clang/test/CIR/Lowering/unary-expr-or-type-trait.cpp (+35)

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index b9e56dc4123d6..19d57ed9cf6fa 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -92,6 +92,8 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
 
   mlir::Value VisitCastExpr(CastExpr *E);
 
+  mlir::Value VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *e);
+
   /// Emit a conversion from the specified type to the specified destination
   /// type, both of which are CIR scalar types.
   /// TODO: do we need ScalarConversionOpts here? Should be done in another
@@ -148,3 +150,27 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *ce) {
   }
   return {};
 }
+
+/// Return the size or alignment of the type of argument of the sizeof
+/// expression as an integer.
+mlir::Value ScalarExprEmitter::VisitUnaryExprOrTypeTraitExpr(
+    const UnaryExprOrTypeTraitExpr *e) {
+  const QualType typeToSize = e->getTypeOfArgument();
+  if (e->getKind() == UETT_SizeOf) {
+    if (const VariableArrayType *variableArrTy =
+            cgf.getContext().getAsVariableArrayType(typeToSize)) {
+      cgf.getCIRGenModule().errorNYI(e->getSourceRange(),
+                                     "sizeof operator for VariableArrayType",
+                                     e->getStmtClassName());
+    }
+  } else if (e->getKind() == UETT_OpenMPRequiredSimdAlign) {
+    cgf.getCIRGenModule().errorNYI(
+        e->getSourceRange(),
+        "sizeof operator for Not yet implemented: ", e->getStmtClassName());
+  }
+
+  return builder.create<cir::ConstantOp>(
+      cgf.getLoc(e->getSourceRange()), cgf.cgm.UInt64Ty,
+      builder.getAttr<cir::IntAttr>(
+          cgf.cgm.UInt64Ty, e->EvaluateKnownConstInt(cgf.getContext())));
+}
diff --git a/clang/test/CIR/CodeGen/unary-expr-or-type-trait.cpp b/clang/test/CIR/CodeGen/unary-expr-or-type-trait.cpp
new file mode 100644
index 0000000000000..e1868d99c42b6
--- /dev/null
+++ b/clang/test/CIR/CodeGen/unary-expr-or-type-trait.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - 2>&1 | filecheck %s
+
+void foo() {
+  unsigned long b = sizeof(bool);
+  // CHECK: cir.const #cir.int<1> : !cir.int<u, 64>
+
+  unsigned long i = sizeof(int);
+  // CHECK: cir.const #cir.int<4> : !cir.int<u, 64>
+
+  unsigned long l =  sizeof(long);
+  // CHECK: cir.const #cir.int<8> : !cir.int<u, 64>
+
+  unsigned long f =  sizeof(float);
+  // CHECK: cir.const #cir.int<4> : !cir.int<u, 64>
+
+  unsigned long d =  sizeof(double);
+  // CHECK: cir.const #cir.int<8> : !cir.int<u, 64>
+}
+
+void foo2() {
+  unsigned long b = alignof(bool);
+  // CHECK: cir.const #cir.int<1> : !cir.int<u, 64>
+
+  unsigned long i = alignof(int);
+  // CHECK: cir.const #cir.int<4> : !cir.int<u, 64>
+
+  unsigned long l =  alignof(long);
+  // CHECK: cir.const #cir.int<8> : !cir.int<u, 64>
+
+  unsigned long f =  alignof(float);
+  // CHECK: cir.const #cir.int<4> : !cir.int<u, 64>
+
+  unsigned long d =  alignof(double);
+  // CHECK: cir.const #cir.int<8> : !cir.int<u, 64>
+}
diff --git a/clang/test/CIR/Lowering/unary-expr-or-type-trait.cpp b/clang/test/CIR/Lowering/unary-expr-or-type-trait.cpp
new file mode 100644
index 0000000000000..551a1c254216b
--- /dev/null
+++ b/clang/test/CIR/Lowering/unary-expr-or-type-trait.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - 2>&1 | FileCheck %s
+
+void foo() {
+  unsigned long b = sizeof(bool);
+  // CHECK: store i64 1, ptr {{%.*}}, align 4
+
+  unsigned long i = sizeof(int);
+  // CHECK: store i64 4, ptr {{%.*}}, align 4
+
+  unsigned long l =  sizeof(long);
+  // CHECK: store i64 8, ptr {{%.*}}, align 4
+
+  unsigned long f =  sizeof(float);
+  // CHECK: store i64 4, ptr {{%.*}}, align 4
+
+  unsigned long d =  sizeof(double);
+  // CHECK: store i64 8, ptr {{%.*}}, align 4
+}
+
+void foo2() {
+  unsigned long b = alignof(bool);
+  // CHECK: store i64 1, ptr {{%.*}}, align 4
+
+  unsigned long i = alignof(int);
+  // CHECK: store i64 4, ptr {{%.*}}, align 4
+
+  unsigned long l =  alignof(long);
+  // CHECK: store i64 8, ptr {{%.*}}, align 4
+
+  unsigned long f =  alignof(float);
+  // CHECK: store i64 4, ptr {{%.*}}, align 4
+
+  unsigned long d =  alignof(double);
+  // CHECK: store i64 8, ptr {{%.*}}, align 4
+}

[erichkeane]

See here:

llvm-project/clang/lib/CodeGen/CGExprScalar.cpp

Line 3471 in dc23234

ScalarExprEmitter::VisitUnaryExprOrTypeTraitExpr(

This is missing A LOT of those things it needs. I think this function needs more work (even if it is just NYI).

[erichkeane]

How is this recovering? Will there be a known-const-int in this case to give a valid value? Same on 169.

[AmrDeveloper]

I will check EvaluateKnownConstInt and create a dummy value for recovering

[erichkeane]

I think instead that after each of these errorNYI diagnostics, we are better just returning a constant value that is reasonably sensible. A 1 or a ptr-size both seem reasonable to me.

[AmrDeveloper]

Nice i used 1 as recovering value for unimplemented yet cases

[AmrDeveloper]

I updated the test to include fixed size ArrayType