[llvm-reduce] Actually skip invalid candidates in operands-to-args

[aeubanks]

Summary

This was checked while counting but not actually when doing the reduction, resulting in crashes.

[Meinersbur]

LGTM, thanks

llvm/test/tools/llvm-reduce/operands-to-args.ll

 
 
 define void @func_caller() {
 entry:
   call void @func(i32 21)
   ret void
 }
 
+
+; Make sure to skip functions with non-direct call users
+declare void @e(i8*)
+
+; INTERESTING-LABEL: define void @g() {
+define void @g() {
+  call void @e(i8* bitcast (void (i8**)* @f to i8*))
+  ret void
+}
+
+; INTERESTING-LABEL: define void @f(i8** %a) {
+define void @f(i8** %a) {
+  %1 = load i8*, i8** %a
+  %2 = bitcast i8* %1 to i32*
+  ret void
+}

llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp

static void substituteOperandWithArgument(Function *OldF,
   OldF->replaceAllUsesWith(ConstantExpr::getBitCast(NewF, OldF->getType()));
   OldF->eraseFromParent();
   NewF->setName(FName);
 }
 
 static void reduceOperandsToArgs(Oracle &O, Module &Program) {
   SmallVector<Use *> OperandsToReduce;
   for (Function &F : make_early_inc_range(Program.functions())) {
+    if (!canReplaceFunction(&F))
+      continue;
     OperandsToReduce.clear();
     for (Instruction &I : instructions(&F)) {
       for (Use &Op : I.operands()) {
         if (!canReduceUse(Op))
           continue;
         if (O.shouldKeep())
           continue;