[flang-commits] [flang] [flang][CodeGen] Use a signless attribute for the addendum flag masks (PR #218606)

[Christian Ulmann via flang-commits]

https://github.com/Dinistro created https://github.com/llvm/llvm-project/pull/218606

The descriptor addendum flag masks were built as `ui8` attributes but attached to `i8` constants:

```
llvm.mlir.constant(254 : ui8) : i8
```

The LLVM dialect only models signless integers, so the attribute type and the result type disagree. Use the signless `i8` type for the attribute as well; the bit patterns are unchanged, only their printed form is (`254 : ui8` becomes `-2 : i8`).

>From eb4f41745ccc2f47645e7d2e0e4cc5b6cb1572c3 Mon Sep 17 00:00:00 2001
From: Christian Ulmann <christian.ulmann at nextsilicon.com>
Date: Tue, 25 Aug 2026 08:36:08 +0200
Subject: [PATCH] [flang][CodeGen] Use a signless attribute for the addendum
 flag masks

The descriptor addendum flag masks were built as `ui8` attributes but attached
to `i8` constants:

  llvm.mlir.constant(254 : ui8) : i8

The LLVM dialect only models signless integers, so the attribute type and the
result type disagree. Use the signless `i8` type for the attribute as well; the
bit patterns are unchanged, only their printed form is (`254 : ui8` becomes
`-2 : i8`).

Co-Authored-By: Claude Opus 5 (1M context) <noreply at anthropic.com>
---
 flang/lib/Optimizer/CodeGen/CodeGen.cpp | 4 ++--
 flang/test/Fir/convert-to-llvm.fir      | 4 ++--
 flang/test/Fir/tbaa.fir                 | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index 7696f5f900c5e..589b143a6c58b 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -1931,14 +1931,14 @@ struct EmboxCommonConversion : public fir::FIROpConversion<OP> {
       // destination box.
       if (hasAddendum) {
         auto maskAttr = mlir::IntegerAttr::get(
-            rewriter.getIntegerType(8, /*isSigned=*/false),
+            rewriter.getI8Type(),
             llvm::APInt(8, (uint64_t)_CFI_ADDENDUM_FLAG, /*isSigned=*/false));
         mlir::LLVM::ConstantOp mask = mlir::LLVM::ConstantOp::create(
             rewriter, loc, rewriter.getI8Type(), maskAttr);
         extraField = mlir::LLVM::OrOp::create(rewriter, loc, extraField, mask);
       } else {
         auto maskAttr = mlir::IntegerAttr::get(
-            rewriter.getIntegerType(8, /*isSigned=*/false),
+            rewriter.getI8Type(),
             llvm::APInt(8, (uint64_t)~_CFI_ADDENDUM_FLAG, /*isSigned=*/true));
         mlir::LLVM::ConstantOp mask = mlir::LLVM::ConstantOp::create(
             rewriter, loc, rewriter.getI8Type(), maskAttr);
diff --git a/flang/test/Fir/convert-to-llvm.fir b/flang/test/Fir/convert-to-llvm.fir
index fe803ea2e65af..f621c5715e43f 100644
--- a/flang/test/Fir/convert-to-llvm.fir
+++ b/flang/test/Fir/convert-to-llvm.fir
@@ -2253,7 +2253,7 @@ func.func @test_rebox_1(%arg0: !fir.box<!fir.array<?x?xf32>>) {
 //CHECK:    %[[OTHER_ATTR:.*]] = llvm.mlir.constant(0 : i32) : i32
 //CHECK:    %[[OTHER_ATTR_I8:.*]] = llvm.trunc %[[OTHER_ATTR]] : i32 to i8
 //CHECK:    %[[RBOX_TMP5:.*]] = llvm.insertvalue %[[OTHER_ATTR_I8]], %[[RBOX_TMP4]][5] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>)>
-//CHECK:    %[[MASK:.*]] = llvm.mlir.constant(254 : ui8) : i8
+//CHECK:    %[[MASK:.*]] = llvm.mlir.constant(-2 : i8) : i8
 //CHECK:    %[[EXTRA_WITH_ADDENDUM_CORRECTION:.*]] = llvm.and %[[EXTRA]], %[[MASK]]  : i8
 //CHECK:    %[[RBOX_TMP6:.*]] = llvm.insertvalue %[[EXTRA_WITH_ADDENDUM_CORRECTION]], %[[RBOX_TMP5]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>)>
 //CHECK:    %[[DIM1_STRIDE_REF:.*]] = llvm.getelementptr %[[ARG0]][0, 7, 0, 2] : (!llvm.ptr) -> !llvm.ptr, !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<2 x array<3 x i64>>)>
@@ -2323,7 +2323,7 @@ func.func @foo(%arg0: !fir.box<!fir.array<?x!fir.type<t{i:i32,c:!fir.char<1,10>}
 //CHECK:   %[[TYPE_CHAR_I8:.*]] = llvm.trunc %[[TYPE_CHAR]] : i32 to i8
 //CHECK:   %[[RBOX_TMP4:.*]] = llvm.insertvalue %[[TYPE_CHAR_I8]], %[[RBOX_TMP3]][4] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>)>
 //CHECK:   %[[RBOX_TMP5:.*]] = llvm.insertvalue %{{.*}}, %[[RBOX_TMP4]][5] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>)>
-//CHECK:   %[[MASK:.*]] = llvm.mlir.constant(254 : ui8) : i8
+//CHECK:   %[[MASK:.*]] = llvm.mlir.constant(-2 : i8) : i8
 //CHECK:   %[[EXTRA_WITH_ADDENDUM_CORRECTION:.*]] = llvm.and %[[EXTRA]], %[[MASK]]  : i8
 //CHECK:   %[[RBOX_TMP6:.*]] = llvm.insertvalue %[[EXTRA_WITH_ADDENDUM_CORRECTION]], %[[RBOX_TMP5]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>)>
 //CHECK:   %[[SRC_STRIDE_PTR:.*]] = llvm.getelementptr %[[ARG0]][0, 7, 0, 2] : (!llvm.ptr) -> !llvm.ptr, !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
diff --git a/flang/test/Fir/tbaa.fir b/flang/test/Fir/tbaa.fir
index 073eb65c7f449..4f7560d5abbb8 100644
--- a/flang/test/Fir/tbaa.fir
+++ b/flang/test/Fir/tbaa.fir
@@ -67,7 +67,7 @@ module {
 // CHECK:           %[[VAL_33:.*]] = llvm.mlir.constant(0 : i32) : i32
 // CHECK:           %[[VAL_34:.*]] = llvm.trunc %[[VAL_33]] : i32 to i8
 // CHECK:           %[[VAL_35:.*]] = llvm.insertvalue %[[VAL_34]], %[[VAL_32]][5] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
-// CHECK:           %[[VAL_36:.*]] = llvm.mlir.constant(1 : ui8) : i8
+// CHECK:           %[[VAL_36:.*]] = llvm.mlir.constant(1 : i8) : i8
 // CHECK:           %[[VAL_37:.*]] = llvm.or %[[EXTRA]], %[[VAL_36]]  : i8
 // CHECK:           %[[VAL_38:.*]] = llvm.insertvalue %[[VAL_37]], %[[VAL_35]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
 // CHECK:           %[[VAL_40B:.*]] = llvm.insertvalue %[[VAL_19]], %[[VAL_38]][7] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>