https://github.com/steffenlarsen created 
https://github.com/llvm/llvm-project/pull/220576

A target builtin with no special case is emitted through the generic intrinsic 
path, which returns the intrinsic's own result type. For a builtin declared to 
return bool that type is i1, which CIR models as !cir.int<u, 1> rather than 
!cir.bool. cir.if accepts only !cir.bool, so CIR builtin handling needs to 
convert i1 results to !cir.bool when used in this context.

This is verified using __builtin_amdgcn_is_shared.

>From d54fdf0279d4a02b35f5efa8ddf1b9c635f23417 Mon Sep 17 00:00:00 2001
From: Steffen Holst Larsen <[email protected]>
Date: Tue, 1 Sep 2026 09:00:07 -0500
Subject: [PATCH] [CIR] Convert i1 intrinsic results for bool-returning
 builtins

A target builtin with no special case is emitted through the generic
intrinsic path, which returns the intrinsic's own result type. For a
builtin declared to return bool that type is i1, which CIR models as
!cir.int<u, 1> rather than !cir.bool. cir.if accepts only !cir.bool,
so CIR builtin handling needs to convert i1 results to !cir.bool when
used in this context.

This is verified using __builtin_amdgcn_is_shared.
---
 clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp       |  8 +++++++
 .../CIR/CodeGenHIP/builtin-bool-result.hip    | 21 +++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 clang/test/CIR/CodeGenHIP/builtin-bool-result.hip

diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp 
b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
index 2bab83ddc1f17..0dc240f7c2052 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -2723,6 +2723,14 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl 
&gd, unsigned builtinID,
     if (isa<cir::VoidType>(correctedReturnType))
       return RValue::get(nullptr);
 
+    // A bool-returning builtin may back an intrinsic that returns i1; CIR 
needs
+    // those as !cir.bool.
+    if (fd && fd->getReturnType()->isBooleanType() &&
+        mlir::isa<cir::IntType>(intrinsicRes.getType()))
+      intrinsicRes = cir::CastOp::create(
+          builder, getLoc(e->getExprLoc()), convertType(fd->getReturnType()),
+          cir::CastKind::int_to_bool, intrinsicRes);
+
     return RValue::get(intrinsicRes);
   }
 
diff --git a/clang/test/CIR/CodeGenHIP/builtin-bool-result.hip 
b/clang/test/CIR/CodeGenHIP/builtin-bool-result.hip
new file mode 100644
index 0000000000000..7a89e105b22dc
--- /dev/null
+++ b/clang/test/CIR/CodeGenHIP/builtin-bool-result.hip
@@ -0,0 +1,21 @@
+// REQUIRES: amdgpu-registered-target
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fclangir -fcuda-is-device \
+// RUN: -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fcuda-is-device -emit-llvm %s \
+// RUN: -o - | FileCheck %s
+
+// Checks that builtins returning an i1 can be used as bool results implicitly.
+
+#define __device__ __attribute__((device))
+
+// CHECK-LABEL: @_Z2shPv
+// CHECK: call i1 @llvm.amdgcn.is.shared(ptr
+__device__ bool sh(void *p) { return __builtin_amdgcn_is_shared(p); }
+
+// CHECK-LABEL: @_Z3usePv
+// CHECK: call i1 @llvm.amdgcn.is.shared(ptr
+__device__ int use(void *p) {
+  if (__builtin_amdgcn_is_shared(p))
+    return 1;
+  return 0;
+}

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