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llvm-reduce: Fix overly conservative operands-to-args user restriction #133854

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Merged
merged 1 commit into from
Apr 10, 2025
Merged

llvm-reduce: Fix overly conservative operands-to-args user restriction #133854

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6 changes: 3 additions & 3 deletions llvm/test/tools/llvm-reduce/operands-to-args.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -77,15 +77,15 @@ define void @f(ptr %a) {
@gv_init_use = global [1 x ptr] [ptr @has_global_init_user]

; INTERESTING-LABEL: define void @has_global_init_user(
; REDUCED-LABEL: define void @has_global_init_user() {
; REDUCED-LABEL: define void @has_global_init_user(ptr %Local) {
define void @has_global_init_user() {
%Local = alloca i32, align 4
store i32 42, ptr %Local, align 4
ret void
}

; INTERESTING-LABEL: define void @has_callee_and_arg_user(
; REDUCED-LABEL: define void @has_callee_and_arg_user(ptr %orig.arg) {
; REDUCED-LABEL: define void @has_callee_and_arg_user(ptr %orig.arg, ptr %Local) {
define void @has_callee_and_arg_user(ptr %orig.arg) {
%Local = alloca i32, align 4
store i32 42, ptr %Local, align 4
Expand All @@ -96,7 +96,7 @@ declare void @ptr_user(ptr)

; INTERESTING-LABEL: define void @calls_and_passes_func(
; REDUCED-LABEL: define void @calls_and_passes_func(ptr %has_callee_and_arg_user) {
; REDUCED: call void @has_callee_and_arg_user(ptr %has_callee_and_arg_user)
; REDUCED: call void @has_callee_and_arg_user(ptr %has_callee_and_arg_user, ptr null)
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why do we pass null here now, should we not ideally introduce a new argument?

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@arsenm arsenm Apr 1, 2025 •
edited
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Whenever this this does anything, the call sites are adjusted to pass the default type value to the new argument

define void @calls_and_passes_func() {
call void @has_callee_and_arg_user(ptr @has_callee_and_arg_user)
ret void
Expand Down
16 changes: 7 additions & 9 deletions llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,12 +19,9 @@

using namespace llvm;

static bool canReplaceFunction(Function *F) {
return all_of(F->uses(), [](Use &Op) {
if (auto *CI = dyn_cast<CallBase>(Op.getUser()))
return &CI->getCalledOperandUse() == &Op;
return false;
});
static bool canReplaceFunction(const Function &F) {
// TODO: Add controls to avoid ABI breaks (e.g. don't break main)
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IMO llvm-reduce should be reducing main

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I'd just remove this

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It shoul, but it would be useful to have a mode to opt out and avoid breaking anything needed to execute the function (bugpoint has a more primitive version of the option than the one I would like)

return true;
}

static bool canReduceUse(Use &Op) {
Expand Down Expand Up @@ -59,8 +56,9 @@ static bool canReduceUse(Use &Op) {
static void replaceFunctionCalls(Function *OldF, Function *NewF) {
SmallVector<CallBase *> Callers;
for (Use &U : OldF->uses()) {
auto *CI = cast<CallBase>(U.getUser());
assert(&U == &CI->getCalledOperandUse());
auto *CI = dyn_cast<CallBase>(U.getUser());
if (!CI || !CI->isCallee(&U)) // RAUW can handle these fine.
continue;

Function *CalledF = CI->getCalledFunction();
if (CalledF == OldF) {
Expand Down Expand Up @@ -209,7 +207,7 @@ void llvm::reduceOperandsToArgsDeltaPass(Oracle &O, ReducerWorkItem &WorkItem) {

SmallVector<Use *> OperandsToReduce;
for (Function &F : make_early_inc_range(Program.functions())) {
if (!canReplaceFunction(&F))
if (!canReplaceFunction(F))
continue;
OperandsToReduce.clear();
for (Instruction &I : instructions(&F)) {
Expand Down