Prohibit use of _ExtInt in atomic intrinsic

The _ExtInt type allows custom width integers, but the atomic memory
access's operand must have a power-of-two size. _ExtInts with
non-power-of-two size should not be allowed for atomic intrinsic.

Before this change:

$ cat test.c

typedef unsigned _ExtInt(42) dtype;
void verify_binary_op_nand(dtype* pval1, dtype val2)
{    __sync_nand_and_fetch(pval1, val2); }

$ clang test.c

clang-11:
/home/ubuntu/llvm_workspace/llvm/clang/lib/CodeGen/CGBuiltin.cpp:117:
llvm::Value*
EmitToInt(clang::CodeGen::CodeGenFunction&, llvm::Value*,
clang::QualType, llvm::IntegerType*): Assertion `V->getType() ==
IntType' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the
crash backtrace, preprocessed source, and associated run script.

After this change:

$ clang test.c

test.c:3:30: error: Atomic memory operand must have a power-of-two size
{    __sync_nand_and_fetch(pval1, val2); }
^

List of the atomic intrinsics that have this
problem:

__sync_fetch_and_add
__sync_fetch_and_sub
__sync_fetch_and_or
__sync_fetch_and_and
__sync_fetch_and_xor
__sync_fetch_and_nand
__sync_nand_and_fetch
__sync_and_and_fetch
__sync_add_and_fetch
__sync_sub_and_fetch
__sync_or_and_fetch
__sync_xor_and_fetch
__sync_fetch_and_min
__sync_fetch_and_max
__sync_fetch_and_umin
__sync_fetch_and_umax
__sync_val_compare_and_swap
__sync_bool_compare_and_swap

Differential Revision: https://reviews.llvm.org/D83340

1 files changed, 9 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index efaf36a..509d88e 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -5349,6 +5349,15 @@ Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
   // gracefully.
   TheCall->setType(ResultType);
 
+  // Prohibit use of _ExtInt with atomic builtins.
+  // The arguments would have already been converted to the first argument's
+  // type, so only need to check the first argument.
+  const auto *ExtIntValType = ValType->getAs<ExtIntType>();
+  if (ExtIntValType && !llvm::isPowerOf2_64(ExtIntValType->getNumBits())) {
+    Diag(FirstArg->getExprLoc(), diag::err_atomic_builtin_ext_int_size);
+    return ExprError();
+  }
+
   return TheCallResult;
 }