[PATCH 65/73] builtin: Support __builtin_infer_alloc_token() as a size_t ICE

[Bart Van Assche <bvanassche@acm.org>]

Declare __builtin_infer_alloc_token() returning size_t_ctype and fold
calls to integer constant expression 0 (CEF_SET_ICE) while evaluating all
arguments without type restrictions.

Support __kmalloc_token(...) in the Linux kernel's slab allocator on both
32-bit and 64-bit targets without an #ifdef __CHECKER__ workaround, and
add validation/builtin-infer-alloc-token.c.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 builtin.c                              | 21 +++++++++++++++++++
 validation/builtin-infer-alloc-token.c | 28 ++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 validation/builtin-infer-alloc-token.c

diff --git a/builtin.c b/builtin.c
index 0be03c51aedd..ba3326970391 100644
--- a/builtin.c
+++ b/builtin.c
@@ -638,6 +638,26 @@ static struct symbol_op object_size_op = {
 	.expand = expand_object_size,
 };
 
+static int evaluate_infer_alloc_token(struct expression *expr)
+{
+	expr->flags |= CEF_SET_ICE;
+	return 1;
+}
+
+static int expand_infer_alloc_token(struct expression *expr, int cost)
+{
+	expr->flags = CEF_SET_ICE;
+	expr->type = EXPR_VALUE;
+	expr->value = 0;
+	expr->taint = 0;
+	return 0;
+}
+
+static struct symbol_op infer_alloc_token_op = {
+	.evaluate = evaluate_infer_alloc_token,
+	.expand = expand_infer_alloc_token,
+};
+
 static int args_va_start(struct expression *expr)
 {
 	struct symbol *sym = expr->fn->ctype;
@@ -865,6 +885,7 @@ static const struct builtin_fn builtins_common[] = {
 	{ "__builtin_index", &string_ctype, 0, { &const_string_ctype, &int_ctype }},
 	{ "__builtin_inf", &double_ctype, 0 },
 	{ "__builtin_inff", &float_ctype, 0 },
+	{ "__builtin_infer_alloc_token", size_t_ctype, 1, .op = &infer_alloc_token_op },
 	{ "__builtin_infl", &ldouble_ctype, 0 },
 	{ "__builtin_isdigit", &int_ctype, 0, { &int_ctype }, .op = &isdigit_op },
 	{ "__builtin_isfinite", &int_ctype, 1, .op = &fp_unop_op },
diff --git a/validation/builtin-infer-alloc-token.c b/validation/builtin-infer-alloc-token.c
new file mode 100644
index 000000000000..0ec460d80edb
--- /dev/null
+++ b/validation/builtin-infer-alloc-token.c
@@ -0,0 +1,28 @@
+typedef struct { __SIZE_TYPE__ v; } kmalloc_token_t;
+
+_Static_assert(__builtin_infer_alloc_token(1) == 0, "infer_alloc_token ICE");
+_Static_assert(__builtin_infer_alloc_token(1, 2) == 0, "infer_alloc_token 2-arg ICE");
+_Static_assert(__builtin_types_compatible_p(typeof(__builtin_infer_alloc_token(1)),
+					    __SIZE_TYPE__), "size_t return type");
+
+static const __SIZE_TYPE__ static_tok = __builtin_infer_alloc_token(64);
+
+static __SIZE_TYPE__ test_infer(int size, int flags)
+{
+	__SIZE_TYPE__ tok = __builtin_infer_alloc_token(size, flags);
+	return tok + static_tok;
+}
+
+static __SIZE_TYPE__ test_infer_single(int size)
+{
+	return __builtin_infer_alloc_token(size);
+}
+
+static kmalloc_token_t test_struct(int size)
+{
+	return (kmalloc_token_t){ .v = __builtin_infer_alloc_token(size) };
+}
+
+/*
+ * check-name: builtin-infer-alloc-token
+ */