[CIR] Upstream handling of integral-to-pointer casts #161653

kimsh02 · 2025-10-02T11:40:21Z

Fix #153658

Handle integral to pointer casts and port the relevant cast.cpp test cases from incubator.

llvmbot · 2025-10-02T11:40:56Z

@llvm/pr-subscribers-clangir

@llvm/pr-subscribers-clang

Author: Shawn K (kimsh02)

Changes

Fix #153658

Handle integral to pointer casts and port the relevant cast.cpp test cases from incubator.

Full diff: https://github.com/llvm/llvm-project/pull/161653.diff

3 Files Affected:

(modified) clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h (+18)
(modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+19)
(modified) clang/test/CIR/CodeGen/cast.cpp (+22)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h b/clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h
index 417a226e44cbf..c7450d8770714 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h
+++ b/clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h
@@ -14,6 +14,11 @@
 
 #include "mlir/Dialect/DLTI/DLTI.h"
 #include "mlir/IR/BuiltinOps.h"
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/Support/Alignment.h"
+#include "llvm/Support/TypeSize.h"
 
 namespace cir {
 
@@ -81,6 +86,19 @@ class CIRDataLayout {
   }
 
   llvm::TypeSize getTypeSizeInBits(mlir::Type ty) const;
+
+    llvm::TypeSize getPointerTypeSizeInBits(mlir::Type Ty) const {
+    assert(mlir::isa<cir::PointerType>(Ty) &&
+           "This should only be called with a pointer type");
+    return layout.getTypeSizeInBits(Ty);
+  }
+
+  mlir::Type getIntPtrType(mlir::Type Ty) const {
+    assert(mlir::isa<cir::PointerType>(Ty) && "Expected pointer type");
+    auto IntTy =
+        cir::IntType::get(Ty.getContext(), getPointerTypeSizeInBits(Ty), false);
+    return IntTy;
+  }
 };
 
 } // namespace cir
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index 500007f6f241b..c64c5f7d7a9c8 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -1889,6 +1889,25 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *ce) {
     }
     return v;
   }
+  case CK_IntegralToPointer: {
+    auto DestCIRTy = cgf.convertType(destTy);
+    mlir::Value Src = Visit(const_cast<Expr *>(subExpr));
+
+    // Properly resize by casting to an int of the same size as the pointer.
+    // Clang's IntegralToPointer includes 'bool' as the source, but in CIR
+    // 'bool' is not an integral type.  So check the source type to get the
+    // correct CIR conversion.
+    auto MiddleTy = cgf.cgm.getDataLayout().getIntPtrType(DestCIRTy);
+    auto MiddleVal = builder.createCast(subExpr->getType()->isBooleanType()
+                                            ? cir::CastKind::bool_to_int
+                                            : cir::CastKind::integral,
+                                        Src, MiddleTy);
+
+    if (cgf.cgm.getCodeGenOpts().StrictVTablePointers)
+      llvm_unreachable("NYI");
+
+    return builder.createIntToPtr(MiddleVal, DestCIRTy);
+  }  
 
   case CK_ArrayToPointerDecay:
     return cgf.emitArrayToPointerDecay(subExpr).getPointer();
diff --git a/clang/test/CIR/CodeGen/cast.cpp b/clang/test/CIR/CodeGen/cast.cpp
index 7afa955cf3bcf..a1fd92612fe37 100644
--- a/clang/test/CIR/CodeGen/cast.cpp
+++ b/clang/test/CIR/CodeGen/cast.cpp
@@ -131,3 +131,25 @@ void bitcast() {
 
 // LLVM: %[[D_VEC:.*]] = load <2 x double>, ptr {{.*}}, align 16
 // LLVM: %[[I_VEC:.*]] = bitcast <2 x double> %[[D_VEC]] to <4 x i32>
+
+void f(long int start) {
+  void *p = (void*)start;
+}
+// CIR: %[[L:.*]] = cir.load {{.*}} : !cir.ptr<!s64i>, !s64i
+// CIR: %[[MID:.*]] = cir.cast integral %[[L]] : !s64i -> !u64i
+// CIR:          cir.cast int_to_ptr %[[MID]] : !u64i -> !cir.ptr<!void>
+
+struct A { int x; };
+
+void int_cast(long ptr) {
+  ((A *)ptr)->x = 0;
+}
+// CIR: cir.cast int_to_ptr {{.*}} : !u64i -> !cir.ptr<!rec_A>
+// LLVM: inttoptr {{.*}} to ptr
+
+void null_cast(long) {
+  *(int *)0 = 0;
+  ((A *)0)->x = 0;
+}
+// CIR: #cir.ptr<null> : !cir.ptr<!s32i>
+// CIR: #cir.ptr<null> : !cir.ptr<!rec_A>

github-actions · 2025-10-02T11:42:48Z

✅ With the latest revision this PR passed the C/C++ code formatter.

andykaylor

Thanks for the PR!

What you've done here is basically correct. I have a lot of comments, but they're all just a matter of adapting to the expectations for upstreaming CIR code. I hope you won't be discouraged.

clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

clang/test/CIR/CodeGen/cast.cpp

andykaylor · 2025-10-02T15:56:53Z

clang/test/CIR/CodeGen/cast.cpp

+// CIR: #cir.ptr<null> : !cir.ptr<!s32i>
+// CIR: #cir.ptr<null> : !cir.ptr<!rec_A>


These checks need to be expanded. The CIR generated should look like this:

%1 = cir.const #cir.int<0> : !s32i %2 = cir.const #cir.ptr<null> : !cir.ptr<!s32i> cir.store align(4) %1, %2 : !s32i, !cir.ptr<!s32i> %3 = cir.const #cir.int<0> : !s32i %4 = cir.const #cir.ptr<null> : !cir.ptr<!rec_A> %5 = cir.get_member %4[0] {name = "x"} : !cir.ptr<!rec_A> -> !cir.ptr<!s32i> cir.store align(4) %3, %5 : !s32i, !cir.ptr<!s32i>

The point of the test is to verify that we're using a null pointer in the expected instructions, so I'd check at least that (and always use regex substitutions for SSA values):

// CIR: %[[NULLPTR:.*]] = cir.const #cir.ptr<null> : !cir.ptr<!s32i> // CIR: cir.store{{.*}} %{{.*}}, %[[NULLPTR]] : !s32i, !cir.ptr<!s32i> // CIR: %[[NULLPTR_A:.*]] = cir.const #cir.ptr<null> : !cir.ptr<!rec_A> // CIR: %[[A_X:.*]] = cir.get_member %[[NULLPTR_A]][0] {name = "x"} : !cir.ptr<!rec_A> -> !cir.ptr<!s32i>

Note that I've used %{{.*}} for the value being stored in the second line, because we don't need to test that here. Also note, I used {{.*}} following cir.store so that this test will pass with or without an alignment specifier, because that's not relevant to this test and we wouldn't want to have to update this test if alignment behavior is changed in the future.

Nothing specific to casts is being lowered to LLVM IR, so I don't think LLVM checks are needed here.

Co-authored-by: Andy Kaylor <[email protected]>

kimsh02 · 2025-10-02T17:20:05Z

Thanks for all the helpful feedback! I've applied the suggested commits, and I'll revisit the headers and IR checks.

andykaylor · 2025-10-02T19:14:01Z

Thanks for all the helpful feedback! I've applied the suggested commits, and I'll revisit the headers and IR checks.

My suggested changes didn't include all uses of the variables that were renamed, so you'll need to do that manually, as well as fixing formatting issues.

AmrDeveloper

Thank you @kimsh02 for the PR!

I added some small suggestions

clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

Co-authored-by: Amr Hesham <[email protected]>

kimsh02 · 2025-10-03T11:25:05Z

Thanks, @AmrDeveloper ! I've applied the suggested commits.

kimsh02 · 2025-10-03T11:27:07Z

@andykaylor Yes, thanks for heads up. I will be properly revisiting everything.

AmrDeveloper · 2025-10-04T11:23:37Z

@kimsh02 For code formatting, you can check it locally using git clang-format HEAD~1 (Change 1 for the number of commits you want to check)

https://llvm.org/docs/Contributing.html#how-to-submit-a-patch

Note: For the "Build and Test Linux" the current issue is not related to your PR

kimsh02 · 2025-10-04T16:23:48Z

@AmrDeveloper Thanks!

kimsh02 · 2025-10-07T17:49:58Z

Remove unused headers, apply camel case, CIR test null ptr. 👍

andykaylor

lgtm

AmrDeveloper

LGTM, Thanks

AmrDeveloper · 2025-10-08T16:02:22Z

Let me know if you want help merging it 👍🏻

[CIR] Upstream handling of integral-to-pointer casts

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kimsh02 requested review from lanza, bcardosolopes, xlauko and andykaylor as code owners October 2, 2025 11:40

llvmbot added clang Clang issues not falling into any other category ClangIR Anything related to the ClangIR project labels Oct 2, 2025

Clang-format

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andykaylor reviewed Oct 2, 2025

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kimsh02 and others added 5 commits October 2, 2025 10:10

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

2807388

Co-authored-by: Andy Kaylor <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

d328d27

Co-authored-by: Andy Kaylor <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

ec1ca90

Co-authored-by: Andy Kaylor <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

2b3d7cb

Co-authored-by: Andy Kaylor <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

9a9e05d

Co-authored-by: Andy Kaylor <[email protected]>

AmrDeveloper reviewed Oct 3, 2025

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kimsh02 and others added 5 commits October 3, 2025 04:16

Update clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h

119873c

Co-authored-by: Amr Hesham <[email protected]>

Update clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h

c321248

Co-authored-by: Amr Hesham <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

5866289

Co-authored-by: Amr Hesham <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

728ec84

Co-authored-by: Amr Hesham <[email protected]>

Update clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

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Co-authored-by: Amr Hesham <[email protected]>

Apply feedback

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andykaylor approved these changes Oct 7, 2025

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AmrDeveloper approved these changes Oct 8, 2025

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andykaylor merged commit 33f2668 into llvm:main Oct 8, 2025
9 checks passed

		// CIR: #cir.ptr<null> : !cir.ptr<!s32i>
		// CIR: #cir.ptr<null> : !cir.ptr<!rec_A>

[CIR] Upstream handling of integral-to-pointer casts #161653

[CIR] Upstream handling of integral-to-pointer casts #161653

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