[Clang][Sema] Add __builtin_infer_alloc_token() declaration and semantic checks

[melver]

Introduce the __builtin_infer_alloc_token() builtin declaration and
adds the necessary semantic checks in Sema.

---

This change is part of the following series:

1. [AllocToken] Introduce llvm.alloc.token.id intrinsic #163632
2. [AllocToken] Refactor stateless token calculation into Support #163633
3. [AllocToken] Make token mode a pass parameter #163634
4. [Clang] Move AllocToken frontend options to LangOptions #163635
5. [Clang] Refactor allocation type inference logic #163636
6. [Clang][Sema] Add __builtin_infer_alloc_token() declaration and semantic checks #163638
7. [Clang] Implement constexpr evaluation for __builtin_infer_alloc_token() #163639
8. [Clang][CodeGen] Implement code generation for __builtin_infer_alloc_token() #156842

[llvmbot]

@llvm/pr-subscribers-clang

Author: Marco Elver (melver)

Changes

Introduce the __builtin_infer_alloc_token() builtin declaration and
adds the necessary semantic checks in Sema.

---

This change is part of the following series:

1. [AllocToken] Introduce llvm.alloc.token.id intrinsic #163632
2. [AllocToken] Refactor stateless token calculation into Support #163633
3. [AllocToken] Make token mode a pass parameter #163634
4. [Clang] Move AllocToken frontend options to LangOptions #163635
5. [Clang] Refactor allocation type inference logic #163636
6. [Clang][Sema] Add __builtin_infer_alloc_token() declaration and semantic checks #163638
7. [Clang] Implement constexpr evaluation for __builtin_infer_alloc_token() #163639
8. [Clang][CodeGen] Implement code generation for __builtin_infer_alloc_token() #156842

---

Full diff: https://github.com/llvm/llvm-project/pull/163638.diff

3 Files Affected:

• (modified) clang/include/clang/Basic/Builtins.td (+7)
• (modified) clang/lib/Sema/SemaChecking.cpp (+22)
• (added) clang/test/SemaCXX/alloc-token.cpp (+12)

diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index 792e2e07ec594..c21a048cf68c0 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -4727,6 +4727,13 @@ def PtrauthStringDiscriminator : Builtin {
   let Prototype = "size_t(char const*)";
 }
 
+// AllocToken builtins.
+def InferAllocToken : Builtin {
+  let Spellings = ["__builtin_infer_alloc_token"];
+  let Attributes = [NoThrow, Const, Pure, CustomTypeChecking, Constexpr, UnevaluatedArguments];
+  let Prototype = "size_t(...)";
+}
+
 // OpenCL v2.0 s6.13.16, s9.17.3.5 - Pipe functions.
 // We need the generic prototype, since the packet type could be anything.
 def ReadPipe : OCLPipeLangBuiltin {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 063db05665af1..953428e9e8f34 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1498,6 +1498,24 @@ static void builtinAllocaAddrSpace(Sema &S, CallExpr *TheCall) {
   TheCall->setType(S.Context.getPointerType(RT));
 }
 
+static bool checkBuiltinInferAllocToken(Sema &S, CallExpr *TheCall) {
+  if (S.checkArgCountAtLeast(TheCall, 1))
+    return true;
+
+  for (Expr *Arg : TheCall->arguments()) {
+    // If argument is dependent on a template parameter, we can't resolve now.
+    if (Arg->isTypeDependent() || Arg->isValueDependent())
+      continue;
+    // Reject void types.
+    QualType ArgTy = Arg->IgnoreParenImpCasts()->getType();
+    if (ArgTy->isVoidType())
+      return S.Diag(Arg->getBeginLoc(), diag::err_param_with_void_type);
+  }
+
+  TheCall->setType(S.Context.UnsignedLongLongTy);
+  return false;
+}
+
 namespace {
 enum PointerAuthOpKind {
   PAO_Strip,
@@ -2779,6 +2797,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
       builtinAllocaAddrSpace(*this, TheCall);
     }
     break;
+  case Builtin::BI__builtin_infer_alloc_token:
+    if (checkBuiltinInferAllocToken(*this, TheCall))
+      return ExprError();
+    break;
   case Builtin::BI__arithmetic_fence:
     if (BuiltinArithmeticFence(TheCall))
       return ExprError();
diff --git a/clang/test/SemaCXX/alloc-token.cpp b/clang/test/SemaCXX/alloc-token.cpp
new file mode 100644
index 0000000000000..5c490f2affda8
--- /dev/null
+++ b/clang/test/SemaCXX/alloc-token.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s -fexperimental-new-constant-interpreter
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s -falloc-token-mode=typehash -DMODE_TYPEHASH
+
+#if !__has_builtin(__builtin_infer_alloc_token)
+#error "missing __builtin_infer_alloc_token"
+#endif
+
+void negative_tests() {
+  __builtin_infer_alloc_token(); // expected-error {{too few arguments to function call}}
+  __builtin_infer_alloc_token((void)0); // expected-error {{argument may not have 'void' type}}
+}

[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-armv8-quick running on linaro-clang-armv8-quick while building clang at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/23082

Here is the relevant piece of the build log for the reference

Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'lit :: max-time.py' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 5
env -u FILECHECK_OPTS "/usr/bin/python3.10" /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/lit/lit.py -j1 --order=lexical Inputs/max-time --max-time=5 2>&1  |  FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/utils/lit/tests/max-time.py
# executed command: env -u FILECHECK_OPTS /usr/bin/python3.10 /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/utils/lit/lit.py -j1 --order=lexical Inputs/max-time --max-time=5
# executed command: FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/utils/lit/tests/max-time.py
# .---command stderr------------
# | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/utils/lit/tests/max-time.py:8:10: error: CHECK: expected string not found in input
# | # CHECK: Skipped: 1
# |          ^
# | <stdin>:2:51: note: scanning from here
# | warning: reached timeout, skipping remaining tests
# |                                                   ^
# | <stdin>:7:2: note: possible intended match here
# |  Skipped: 2 (100.00%)
# |  ^
# | 
# | Input file: <stdin>
# | Check file: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/utils/lit/tests/max-time.py
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1: -- Testing: 2 tests, 1 workers -- 
# |            2: warning: reached timeout, skipping remaining tests 
# | check:8'0                                                       X error: no match found
# |            3:  
# | check:8'0     ~
# |            4: Testing Time: 5.34s 
# | check:8'0     ~~~~~~~~~~~~~~~~~~~~
# |            5:  
# | check:8'0     ~
# |            6: Total Discovered Tests: 2 
# | check:8'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            7:  Skipped: 2 (100.00%) 
# | check:8'0     ~~~~~~~~~~~~~~~~~~~~~~
# | check:8'1      ?                     possible intended match
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

********************

[llvm-ci]

LLVM Buildbot has detected a new failure on builder ppc64le-flang-rhel-clang running on ppc64le-flang-rhel-test while building clang at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/41698

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
9.018 [4/29/0] cd /home/buildbots/llvm-external-buildbots/workers/ppc64le-flang-rhel-test/ppc64le-flang-rhel-clang-build/build/runtimes/runtimes-bins && /home/buildbots/llvm-external-buildbots/cmake-3.31.2/bin/cmake --build /home/buildbots/llvm-external-buildbots/workers/ppc64le-flang-rhel-test/ppc64le-flang-rhel-clang-build/build/runtimes/runtimes-bins/ --target libomp-mod --config Release
ninja: no work to do.
9.209 [3/6/25] Building CXX object tools/flang/unittests/Frontend/CMakeFiles/FlangFrontendTests.dir/FrontendActionTest.cpp.o
9.215 [2/5/27] Building CXX object tools/flang/unittests/Optimizer/CMakeFiles/FlangOptimizerTests.dir/RTBuilder.cpp.o
9.230 [2/4/28] Building CXX object tools/flang/unittests/Optimizer/CMakeFiles/FlangOptimizerTests.dir/FIRTypesTest.cpp.o
9.273 [2/3/29] Building CXX object tools/flang/unittests/Optimizer/CMakeFiles/FlangOptimizerTests.dir/FortranVariableTest.cpp.o
9.611 [1/3/30] Linking CXX executable tools/flang/unittests/Common/FlangCommonTests
12.644 [1/2/31] Linking CXX executable tools/flang/unittests/Optimizer/FlangOptimizerTests
19.847 [1/1/32] Linking CXX executable tools/flang/unittests/Frontend/FlangFrontendTests
19.848 [0/1/32] Running the Flang regression tests
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1220.952808