[clang] [CIR] Raise IntType max bitwidth to match LLVM IR (PR #191499)
via cfe-commits
cfe-commits at lists.llvm.org
Tue Apr 14 10:30:34 PDT 2026
https://github.com/adams381 updated https://github.com/llvm/llvm-project/pull/191499
>From 3f0d5ffbec5e0265829c58d9bb3760434861abd1 Mon Sep 17 00:00:00 2001
From: Adam Smith <adams at nvidia.com>
Date: Fri, 10 Apr 2026 12:23:34 -0700
Subject: [PATCH 1/2] [CIR] Raise IntType max bitwidth to match LLVM IR
Increase IntType::maxBitwidth() from 128 to 1<<23 (8388608) so CIR
can represent the full range of _BitInt widths that Clang and LLVM IR
support. Remove the now-dead errorNYI guard for large _BitInt in
CIRGenTypes.
Follow-up to #188113 addressing feedback from @erichkeane.
Made-with: Cursor
---
clang/include/clang/CIR/Dialect/IR/CIRTypes.td | 5 +++--
clang/lib/CIR/CodeGen/CIRGenTypes.cpp | 11 +++--------
clang/test/CIR/CodeGen/bitint.c | 5 +++++
clang/test/CIR/IR/bitint.cir | 5 +++--
4 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
index c8e63a08847fe..504ec850ddb5a 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
@@ -90,8 +90,9 @@ def CIR_IntType : CIR_Type<"Int", "int", [
/// Returns a minimum bitwidth of cir::IntType
static unsigned minBitwidth() { return 1; }
- /// Returns a maximum bitwidth of cir::IntType
- static unsigned maxBitwidth() { return 128; }
+ /// Returns a maximum bitwidth of cir::IntType.
+ /// Matches llvm::IntegerType::MAX_INT_BITS (1 << 23).
+ static unsigned maxBitwidth() { return (1 << 23); }
}];
let genVerifyDecl = 1;
}
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index 9b493263b76c2..3ee8f15c5467b 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -563,14 +563,9 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
case Type::BitInt: {
const auto *bitIntTy = cast<BitIntType>(type);
- if (bitIntTy->getNumBits() > cir::IntType::maxBitwidth()) {
- cgm.errorNYI(SourceLocation(), "large _BitInt type", type);
- resultType = cgm.sInt32Ty;
- } else {
- resultType = cir::IntType::get(&getMLIRContext(), bitIntTy->getNumBits(),
- bitIntTy->isSigned(),
- /*isBitInt=*/true);
- }
+ resultType = cir::IntType::get(&getMLIRContext(), bitIntTy->getNumBits(),
+ bitIntTy->isSigned(),
+ /*isBitInt=*/true);
break;
}
diff --git a/clang/test/CIR/CodeGen/bitint.c b/clang/test/CIR/CodeGen/bitint.c
index 014b315c907ba..6d91986c165ba 100644
--- a/clang/test/CIR/CodeGen/bitint.c
+++ b/clang/test/CIR/CodeGen/bitint.c
@@ -13,19 +13,24 @@
// CIR-DAG: !s128i_bitint = !cir.int<s, 128, bitint>
// CIR-DAG: !u64i_bitint = !cir.int<u, 64, bitint>
// CIR-DAG: !s128i = !cir.int<s, 128>
+// CIR-DAG: !s256i_bitint = !cir.int<s, 256, bitint>
// _BitInt(128) has alignment 8 while __int128 has alignment 16.
signed _BitInt(128) bitint128_var;
__int128 int128_var;
+signed _BitInt(256) bitint256_var;
// CIR: cir.global external @bitint128_var = #cir.int<0> : !s128i_bitint {alignment = 8 : i64}
// CIR: cir.global external @int128_var = #cir.int<0> : !s128i {alignment = 16 : i64}
+// CIR: cir.global external @bitint256_var = #cir.int<0> : !s256i_bitint
// LLVM: @bitint128_var = global i128 0, align 8
// LLVM: @int128_var = global i128 0, align 16
+// LLVM: @bitint256_var = global i256 0
// OGCG: @bitint128_var = global i128 0, align 8
// OGCG: @int128_var = global i128 0, align 16
+// OGCG: @bitint256_var = global i256 0
void take_bitint_32(_BitInt(32) x) {}
// CIR: cir.func {{.*}} @take_bitint_32(%arg0: !s32i_bitint
diff --git a/clang/test/CIR/IR/bitint.cir b/clang/test/CIR/IR/bitint.cir
index 5dddddc833777..c61f1b581b62e 100644
--- a/clang/test/CIR/IR/bitint.cir
+++ b/clang/test/CIR/IR/bitint.cir
@@ -5,10 +5,11 @@
!s32i_bitint = !cir.int<s, 32, bitint>
!u64i_bitint = !cir.int<u, 64, bitint>
!s128i_bitint = !cir.int<s, 128, bitint>
+!s1024i_bitint = !cir.int<s, 1024, bitint>
module {
- // CHECK: cir.func @round_trip_bitint(%arg0: !s32i_bitint, %arg1: !u64i_bitint, %arg2: !s128i_bitint)
- cir.func @round_trip_bitint(%arg0: !s32i_bitint, %arg1: !u64i_bitint, %arg2: !s128i_bitint) {
+ // CHECK: cir.func @round_trip_bitint(%arg0: !s32i_bitint, %arg1: !u64i_bitint, %arg2: !s128i_bitint, %arg3: !s1024i_bitint)
+ cir.func @round_trip_bitint(%arg0: !s32i_bitint, %arg1: !u64i_bitint, %arg2: !s128i_bitint, %arg3: !s1024i_bitint) {
cir.return
}
>From c1397198265c7c8e03c62a4b446f53a4dcddc18f Mon Sep 17 00:00:00 2001
From: Adam Smith <adams at nvidia.com>
Date: Mon, 13 Apr 2026 13:34:22 -0700
Subject: [PATCH 2/2] [CIR] Add _BitInt boundary tests and maxBitwidth assert
Add _BitInt(254) and _BitInt(257) test cases to exercise
non-power-of-2 bitwidths near the 256 boundary. Add a
defense-in-depth assert that the _BitInt width does not
exceed CIR IntType::maxBitwidth().
Addresses review feedback from @erichkeane and @andykaylor.
Made-with: Cursor
---
clang/lib/CIR/CodeGen/CIRGenTypes.cpp | 9 ++++++---
clang/test/CIR/CodeGen/bitint.c | 18 ++++++++++++++++++
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index 3ee8f15c5467b..883b791d5909c 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -563,9 +563,12 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
case Type::BitInt: {
const auto *bitIntTy = cast<BitIntType>(type);
- resultType = cir::IntType::get(&getMLIRContext(), bitIntTy->getNumBits(),
- bitIntTy->isSigned(),
- /*isBitInt=*/true);
+ unsigned numBits = bitIntTy->getNumBits();
+ assert(numBits <= cir::IntType::maxBitwidth() &&
+ "_BitInt width exceeds CIR IntType maximum");
+ resultType =
+ cir::IntType::get(&getMLIRContext(), numBits, bitIntTy->isSigned(),
+ /*isBitInt=*/true);
break;
}
diff --git a/clang/test/CIR/CodeGen/bitint.c b/clang/test/CIR/CodeGen/bitint.c
index 6d91986c165ba..e84b610c171b6 100644
--- a/clang/test/CIR/CodeGen/bitint.c
+++ b/clang/test/CIR/CodeGen/bitint.c
@@ -19,18 +19,26 @@
signed _BitInt(128) bitint128_var;
__int128 int128_var;
signed _BitInt(256) bitint256_var;
+signed _BitInt(254) bitint254_var;
+signed _BitInt(257) bitint257_var;
// CIR: cir.global external @bitint128_var = #cir.int<0> : !s128i_bitint {alignment = 8 : i64}
// CIR: cir.global external @int128_var = #cir.int<0> : !s128i {alignment = 16 : i64}
// CIR: cir.global external @bitint256_var = #cir.int<0> : !s256i_bitint
+// CIR: cir.global external @bitint254_var = #cir.int<0> : !cir.int<s, 254, bitint>
+// CIR: cir.global external @bitint257_var = #cir.int<0> : !cir.int<s, 257, bitint>
// LLVM: @bitint128_var = global i128 0, align 8
// LLVM: @int128_var = global i128 0, align 16
// LLVM: @bitint256_var = global i256 0
+// LLVM: @bitint254_var = global i254 0, align 8
+// LLVM: @bitint257_var = global i257 0, align 8
// OGCG: @bitint128_var = global i128 0, align 8
// OGCG: @int128_var = global i128 0, align 16
// OGCG: @bitint256_var = global i256 0
+// OGCG: @bitint254_var = global i256 0, align 8
+// OGCG: @bitint257_var = global [40 x i8] zeroinitializer, align 8
void take_bitint_32(_BitInt(32) x) {}
// CIR: cir.func {{.*}} @take_bitint_32(%arg0: !s32i_bitint
@@ -47,6 +55,16 @@ void take_unsigned_bitint(unsigned _BitInt(64) x) {}
// LLVM: define {{.*}} void @take_unsigned_bitint(i64 {{.*}})
// OGCG: define {{.*}} void @take_unsigned_bitint(i64 {{.*}})
+void take_bitint_254(signed _BitInt(254) x) {}
+// CIR: cir.func {{.*}} @take_bitint_254(%arg0: !cir.int<s, 254, bitint>
+// LLVM: define {{.*}} void @take_bitint_254(i254 {{.*}})
+// OGCG: define {{.*}} void @take_bitint_254(ptr noundef byval(i256) align 8 {{.*}})
+
+void take_bitint_257(signed _BitInt(257) x) {}
+// CIR: cir.func {{.*}} @take_bitint_257(%arg0: !cir.int<s, 257, bitint>
+// LLVM: define {{.*}} void @take_bitint_257(i257 {{.*}})
+// OGCG: define {{.*}} void @take_bitint_257(ptr noundef byval([40 x i8]) align 8 {{.*}})
+
// Regular __int128 should NOT have the bitint flag.
void take_int128(__int128 x) {}
// CIR: cir.func {{.*}} @take_int128(%arg0: !s128i
More information about the cfe-commits
mailing list