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[IR] Use immarg for preallocated intrinsics (NFC) #155835

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Merged
merged 2 commits into from
Sep 29, 2025
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[IR] Use immarg for preallocated intrinsics (NFC) #155835

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708c018
[IR] Use immarg for preallocated intrinsics (NFC)
nikic Aug 28, 2025
cd339d8
Add test for call.preallocated.arg and restore check
nikic Sep 26, 2025
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8 changes: 6 additions & 2 deletions llvm/include/llvm/IR/Intrinsics.td
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Original file line number Diff line number Diff line change
Expand Up @@ -977,8 +977,12 @@ def int_instrprof_mcdc_tvbitmap_update : Intrinsic<[],
[llvm_ptr_ty, llvm_i64_ty,
llvm_i32_ty, llvm_ptr_ty]>;

def int_call_preallocated_setup : DefaultAttrsIntrinsic<[llvm_token_ty], [llvm_i32_ty]>;
def int_call_preallocated_arg : DefaultAttrsIntrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_i32_ty]>;
def int_call_preallocated_setup
: DefaultAttrsIntrinsic<[llvm_token_ty], [llvm_i32_ty],
[ImmArg<ArgIndex<0>>]>;
def int_call_preallocated_arg
: DefaultAttrsIntrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_i32_ty],
[ImmArg<ArgIndex<1>>]>;
def int_call_preallocated_teardown : DefaultAttrsIntrinsic<[], [llvm_token_ty]>;

// This intrinsic is intentionally undocumented and users shouldn't call it;
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4 changes: 1 addition & 3 deletions llvm/lib/IR/Verifier.cpp
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Expand Up @@ -5869,9 +5869,7 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
break;
}
case Intrinsic::call_preallocated_setup: {
auto *NumArgs = dyn_cast<ConstantInt>(Call.getArgOperand(0));
Check(NumArgs != nullptr,
"llvm.call.preallocated.setup argument must be a constant");
auto *NumArgs = cast<ConstantInt>(Call.getArgOperand(0));
bool FoundCall = false;
for (User *U : Call.users()) {
auto *UseCall = dyn_cast<CallBase>(U);
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10 changes: 9 additions & 1 deletion llvm/test/Verifier/preallocated-invalid.ll
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Expand Up @@ -65,13 +65,21 @@ define void @preallocated_one_call() {
ret void
}

; CHECK: must be a constant
; CHECK: immarg operand has non-immediate parameter
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Missing test for the call_preallocated_arg case?

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Fair, but that's a pre-existing test coverage gap. This stuff relies on shared infrastructure. How much testing of immarg do we need, especially for a feature which was never productionized?

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Heh, this did end up catching an issue in this case. Because part of the validation for preallocated.arg is done when visiting the preallocated.setup, we can't actually assume that the argument is constant in the verifier at that point, so it ended up asserting. I've restored that check, which also means that this doesn't actually produce the immarg message now.

define void @preallocated_setup_constant() {
%ac = call i32 @blackbox()
%cs = call token @llvm.call.preallocated.setup(i32 %ac)
ret void
}

; CHECK: llvm.call.preallocated.alloc arg index must be a constant
define void @preallocated_arg_constant() {
%ac = call i32 @blackbox()
%cs = call token @llvm.call.preallocated.setup(i32 3)
call token @llvm.call.preallocated.arg(token %cs, i32 %ac)
ret void
}

; CHECK: must be between 0 and corresponding
define void @preallocated_setup_arg_index_in_bounds() {
%cs = call token @llvm.call.preallocated.setup(i32 2)
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